Making infrastructure modifications to install launchers and receivers on gas gathering lines will typically cost 5-6 figures per line. The ability to pig gas gathering lines without making such modifications could offer flow assurance and corrosion prevention without the associated cost and downtime.
In this paper we describe the successful use of an elastomeric pig to dewater a gas gathering pipe in Colorado with no launcher or receiver, resulting in the complete restoration of flow in a pipe that had suffered from a differential due to water accumulation in low spots. The pig was inserted at a temporarily dropped spool and removed through a blowdown valve making use of its ability to be extruded through reduced bore piping.
Subsequent to risk based inspection (RBI) and corrosion assessment, it was highlighted that several operator pipelines in the North Sea required internal inspection to verify line conditions and to ensure that the pipelines were fit for purpose. It was recognised that some of these pipelines were not readily equipped for pigging operations and challenges existed to enable inspection of the lines. The most feasible means of obtaining detailed inspection data was to perform intelligent pigging (IP) operations, requiring the installation of temporary subsea launch/receive facilities, which were also used to allow pipeline cleaning using a combination of chemical applications, progressive pigging, and pipeline gauging before the IP tools were run.
Crack inspection of pipelines using conventional ultrasonic technology has become a standard application for in-line inspection (ILI) of liquid pipelines. Crack inspection tools have proven very successful for the detection of various types of cracks (e.g. SCC) or crack-like anomalies present in many pipelines worldwide. The first inspection tools were developed for axial crack inspection (UC), as most cracks or crack-like defects in pipelines are axially orientated. In some cases, however, circumferential cracking can occur prompting the development of tools for circumferential crack inspection (UCc). Standard crack inspection tools can be applied in most liquid pipelines transporting typical crude oils or products (e.g. diesel).
Over the years, specific inspection requirements came up that were not covered by the first tool generations. These requirements are related to different aspects of the inspection process ranging from tool-related characteristics to inspection-related challenges such as crack inspection in liquid gas. Consequently, those challenges are addressed by the latest tool developments allowing an inspection performance not possible before with regard to inspection speed and measuring resolution. In the paper, the achieved progress including enhanced depth sizing is described and illustrated by examples from inspection runs.
In-line inspection of offshore pipelines is a challenging task for several reasons, including:
Offshore pipelines distinguish themselves from onshore lines because external reference measurements and local repairs are often complex and challenging. Furthermore, inspecting offshore pipelines is often more demanding because of logistics, accessibility, and cost.
Consequently, tool performance, first run success, risk mitigation and operational impact are key factors to be considered when selecting an inspection solution. Additionally, in order to successfully execute these inspections, expertise from both the operator and inspection contractor, need to be combined in a multidisciplinary team that operates as ‘one team’ and establishes the confidence and trust in each other to make the correct decisions.
This paper will discuss a recent example of such a challenge: the successful inspection of a key Shell U.K. Limited (Shell) pipeline in the North Sea, which required a bespoke solution to overcome the pigging challenges associated with this pipeline.
The inspection of subsea pipelines, in particular - flowlines and gathering lines – has recently moved into the focus of offshore engineers. Contrary to most long-distance export pipelines many of these lines are unpiggable. While some of these lines can be inspected with tethered internal inspection tools the only inspection options until recently for the majority of the lines were visual testing, CP-surveys and local defect monitoring. With the MEC™-Combi Crawler system and the PECT inspection system it is now possible to gather integrity information to a level of accuracy that can be compared to in-line inspection, but is obtained by external scanning. This level of accuracy permits carrying out defect assessment based on inspection data. Case studies are presented for each inspection technique – Magnetic Eddy Current (MEC) and the Pulsed Eddy Current Technique (PECT) to show how the subsea inspection tools are adapted to fit the specific inspection task.
Traditionally, pipeline pigging has 2 extremes. At one end of the spectrum are cleaning pigs and at the other end are In-Line Inspection (ILI) tools or “intelligent pigs” and there is little that sits between. Cleaning pigs are basic tools that are frequently and easily deployed and carry little operational risk of lodging in the line, however, they gather little or no data. ILI tools are far more complex by design as the industry demands higher specification, greater accuracy and the ability to detect more types of pipeline defects. The consequence of this is larger tools needing specialist technicians, never mind the increased support and handling equipment as well as tight operating parameters and run scheduling. Operators have identified a need for tools in this middle ground of the 2 extremes and have encouraged the development of simple, easy to use and deploy inspection technology that uses advanced electromagnetic sensors integrated on to cleaning tools – or making the simple, smart.
Managing the long term integrity of a critical 10” subsea crude oil pipeline is dependent on being able to use the correct inspection technologies, however, the current structure of the pipeline does not allow for any in-line inspections. Consequently managing the short term integrity of the pipeline becomes a priority until the pipeline is made piggable. This paper describes where and how to investigate along the pipeline to determine the current internal condition of the pipeline.
A desktop feasibility study was completed in order to determine the locations and the confidence in the use of an external ultrasonic scanning survey (auto-UT) to determine the short term integrity of the pipeline. This comprised the following:
In addition a review of the current sacrificial anode protection of the pipeline was completed to ensure that any investigative works completed would not result in any external corrosion issues.
Remote controlled, tethered isolation plugs and hot tap installed line-stop isolation tools are regularly used to provide fully proved double block isolations, enabling valve replacement or repairs without having to depressurise the entire pipeline. This type of isolation work scope could be described as conventional. Although, due to the safety criticality of any pipeline isolation, each application is engineered, tested and risk assessed against project specific parameters.
Isolation plugs are also used in unconventional, innovative ways throughout the pipeline life-cycle – from cradle to grave. This paper will describe case studies where isolation plugs have been used in non-standard ways to solve pipeline problems during the various phases of a pipeline’s life.
During the construction phase, isolation plugs are used to facilitate pipeline recovery in the event of a wet buckle. To enable recovery of large diameter or deep-water pipelines, the catenary section of pipeline to be recovered off the seabed usually requires to be dewatered. To dewater the catenary section, isolation plugs are deployed subsea, either via a diverless subsea launcher or via a pipeline retrieval tool with a cassette sleeve that contains the isolation plug.
During the operational phase, midline sectional replacement and repair may be required. In the case of an unpiggable defect, isolation plugs have been developed that can be pigged from either end of a pipeline towards each other, allowing the isolated section to be vented, cut out and replaced. To facilitate leak-testing following the repair an additional leak-test module is utilised and high-integrity pressure equalisation is used to safely unset the plugs.
Finally, for pipeline abandonment and decommissioning, isolation plugs are used to permanently plug and abandon pipelines. These isolation plugs can also be used to install a subsea bypass allowing platforms to be removed.
Pipeline pigging is a standard regular operational activity performed throughout the pipeline lifecycle and forms part of the Integrity Management System of a pipeline network. Typical examples of pigging applications include pre-commissioning, line-proving, cleaning, liquid removal, batching, inline inspection, inline isolation, and decommissioning. Key to all these activities is the ability to track the pigs in the pipeline, locate the pigs when necessary, and identify each pig when multiple pigs are in use at one time. More complex capabilities required are the ability to communicate, interrogate, and activate the pigs through the pipeline wall and induce sleep modes on transmitters, enabling battery life conservation during long operations.
Pig tracking can be performed by various methods—with devices fitted to the pig such as transmitters (electromagnetic or acoustic signal) or radioactive sources. External devices such as pipeline-fitted pig signaling devices, acoustic listening devices, or pressure pulse monitoring systems can also be used. The operational requirements and limitations of pigging activity will determine the best solution for tracking and monitoring.
Tracking of pigs in an offshore pipeline is challenging due to the environmental conditions. The pipelines tend to be constructed of thicker wall material (>15 mm) and are surrounded by large steel structures (platforms) as well as cyclic oscillating systems (pumps, turbines, etc.). Subsea sections may be covered for protection by rock dump, steel structures or buried below the seabed. These conditions provide challenges to transmitter tracking systems.
In the 1990s, T.D. Williamson designed and developed its proprietary inline isolation SmartPlug® tool, for isolation of a pressurized pipeline. The design requirements of this tool were that it could be pigged to an exact location, and once at the location, it could be remotely activated to effect the isolation. Once activated, it was essential that the system be remotely tested and monitored throughout the duration of the isolation, providing a safe controlled environment for the required works to be carried out. Communication capability at 100% was to be maintained throughout the operation. Due to the criticality of these design requirements, standard off-the-shelf transmitter systems were not found suitable for tracking the SmartPlug isolation tool.
Therefore, T.D. Williamson developed its own purpose-built system to support the SmartPlug tool, which was branded as the SmartTrack™ system.
In line inspections are commonly used to ensure safe operation of oil and gas pipelines. These inspections provide reliable information on the status of the pipeline’s integrity. Traditionally, gas pipelines are inspected using magnetic flux leakage (MFL) technology, and liquid pipelines are inspected using either MFL or ultrasonic wall measurement (UTWM) technology.
Recently, an additional technology has been introduced to the market, based on acoustic resonance technology (ART). This ART technology allows for the inspection of both liquid and gas pipelines with acoustic testing. The ART technology overcomes typical limitations of the prior state of art, such as limited wall thickness capability and speed (for MFL) and cleanliness criteria (for UTWM).
The authors will present the theoretical background of Acoustic Resonance Technology, and practical applications at a product level.
Furthermore, practical applications will be presented where the technology was applied in-field, in the North Sea area. Specifically; 2 occasions will be discussed of crude oil pipelines in the North Sea, which experience wax deposition to such a level that sufficient cleaning for UTWM inspections was not possible or cost-inhibitive.
Ice Pigging is a cleaning technique, mature in the water / wastewater industries, which is being developed for the Oil and Gas industry.
A high-solids ice slurry is pumped under pressure to deliver a wall shear stress on the pipe, cleaning it through physical abrasion. Made of just water and salt, ice pigs do their cleaning, unblocking, debris entraining and transport before melting back into their original components (commonly salt and water); offering a physical clean thousands of times more effective than flushing, without chemicals or risk of getting stuck.
The trails, which are the subject of this paper were commissioned by Royal Dutch Shell plc, using funding from their Gamechanger innovation program.
3D LASER SCANS are becoming increasingly popular for field verifications, and pipeline operators are demanding a corresponding ultra-high-resolution inline inspection technology capable of producing refined integrity calculations.
Ultimately, such an ultra-high-resolution inline inspection technology would lead to improved pipeline safety while simultaneously reducing the need for costly field verifications.
Hence, an ultra-high-resolution MFL technology with sensor spacing similar to that of a 3D laser scan has been developed.
In order to provide reliable inspection results using a ultra-high resolution MFL measurement system, a series of challenges had to be overcome:
In addition to presenting solutions for the above listed technical challenges, this paper will also provide insight into how pipeline integrity management will benefit from ultra-high-resolution MFL inline inspection results.
A 28" sub-sea pipeline supplying gas to Hong Kong was damaged by an anchor drag 278km from Hong Kong in 90m of water. The damage involved two subsea Pipeline End Manifolds (PLEM) and also dented the pipeline adjacent to the North PLEM. This paper details the repair of the damage using a combination of non-piggable and piggable isolation tools.
A model to examine pigging and inspection of gas networks with multiple pipelines, connections and customers is presented in this paper. A case study of a typical gas system with multiple lines, connections and off-takes is presented to demonstrate the use of such a model for planning and executing real life operations. A gas flow rate is provided into the network to the various users of the network or grid. Each customer has a requirement for both a minimum pressure and a minimum flow that cannot be disrupted without agreement or penalty to the operating company. Additionally, inspection or ILI tools must be run within certain velocity constraints to allow reliable data to be achieved. Due to the complexity of the system, there is a risk that the pig could stall in the line as flow is diverted as a result of the pigs own differential pressure. Manipulation of valves and flows must be planned and performed carefully so as not to disrupt the demands of the various customers in the network. Excessive pressure drop across closed valves is undesirable if they are to be opened during the operation. Pigging the system is onerous due to the need to balance the requirements of the pigs and the demands of the customers. The pig run time or expected arrival time with transient events such as valves opening, changes in flows, disruption to customers and other transient events is calculated. The paper presents the model and its use to optimise pigging programs in gas networks.
Pipelines manufactured from corrosion-resistant alloys (CRA) are becoming more common in special applications, in particular with offshore pipelines which are in many cases exposed to a harsh and highly corrosive environment. For many years the inspection of CRA pipelines (solid CRA, clad and lined pipe) was not a high priority. Due to the special composition of these types of line pipe it also posed specific challenges to in-line inspection methods as compared to the inspection of common line pipe.
In this article, the different types of CRA line pipe and the relevant characteristics regarding in-line inspection (metal loss inspection, crack inspection) are described. Typical damage mechanisms (e.g. pitting corrosion) that may develop during operation are illustrated and the specific capabilities that are available for ultrasonic in-line inspection as well as the limitations are explained. Several examples from inspection runs in CRA pipelines are presented demonstrating that reliable in-line inspections with good data quality are feasible to a wide extent.
The Congo River crossing (CRX) pipeline system was built to bring associated gases from various fields to a liquefied natural gas (LNG) processing plant in Soyo, Angola. The pipeline system runs a distance of approximately 140 km from the processing plant to the South Nemba platform located offshore Cabinda via two satellite pigging platforms [north pigging platform (NPP) and south pigging platform (SPP)], which provide the location for a drilled conduit that crosses the Congo River.
The pipeline system comprises four segments (A, B, C, and W), running from the South Nemba platform to the Angola LNG (ALNG) terminal in Soyo.
A service company was contracted to perform pre-commissioning services on each segment independently (flood, clean, gauge, caliper survey, hydrotest) before the close-in spools and subsea structures were installed.
Once all segments were completed and tied in, a global leak test was conducted before commencing dewatering operations. Each segment was bulk dewatered followed by final dewatering and vacuum drying before being packed with nitrogen in preparation for first gas.
During the various campaigns, each segment experienced incidents/problems, ranging from stuck centraliser tools, leaking hot stabs, vessel delays, etc., resulting in major delays to the overall project. The pre-commissioning work was successfully completed in early 2016.
Pipeline Engineering opened a Service Centre within the city of Aberdeen, Scotland in 2008 to offer a pigging tool management and tool refurbishment service to the North Sea Pipeline Operators for their routine pigging tools.
Routine pigging tools are used by the pipeline operators to carry out cleaning operations within the production pipelines without impacting on production flow or revenues.
The Aberdeen Service Centre receipts the pigging tools from the customer post run, and then conducts a full service which comprises of cleaning, stripping, inspection, spares replacement, refurbishment, and final testing. The pigging tools are then ready to be utilised on another routine cleaning run.
Once the pigging tool has been fully serviced, a detailed refurbishment report is submitted to the customer, providing visibility on the pigging tools condition and information of the service work carried out by Pipeline Engineering. This pigging tool management and tool refurbishment service has helped customers make large savings on their annual pigging tool costs, whilst also receiving the required engineering expertise to optimise their pigging operations.
The Aberdeen Service Centre has a pigging tool tracking system in place for each customer which highlights their full pigging tool fleet location, condition, configuration, last test date, run details and GA details. This information was previously submitted to the customer on a weekly basis, along with a summary report of all activities. The customers used this system on a regular basis to monitor their pigging tool logistics, and to advise the platform personnel on what the next pigging requirement were to be.
In Q3 of 2016, Pipeline Engineering has upgraded their pigging tool management service to their customers by introducing an Online Pigging Tool Management System. This online management system, with a personalised customer log in, helps each customer improve visibility of their pigging tool fleet whilst providing the option to remotely access the data via a mobile phone or tablet app. Having such up to date data at hand reduces the customers and/or platforms time spent sourcing the required information via the previous method of emails or saved folders.
As the Oil and Gas industry operates 24/7, Pipeline Engineering has created an excellent solution to provide continual all year support to the pigging industry.
This paper describes the optimisation process for cleaning tool maintenance via some customer case studies, demonstrates the software functionality and describes the benefits of having the data at your fingertips.
FlexIQ™ is a complete offering in the arena of flexible riser integrity management from the strategic alliance of INTECSEA and Innospection. This partnership looks to redefine the approach to flexible riser integrity management by offering the best in inspection and computational simulation techniques as part of an Integrity Management Framework. This, in turn, leads to a significant improvement in understanding operational risk and enables a fully integrated service for inspection, analysis and data management. An overview and benefits of the offering will be presented:
Safe operation of pipelines carrying corrosive products or in a corrosive environment requires (i) an understanding of the corrosion threats, (ii) the ability to estimate corrosion growth rates (CGR) of features; and (iii) the ability to apply these rates to plan future inspections, repairs and replacements. Reducing uncertainties in corrosion behaviour will therefore result in safer, more cost efficient operation.
This paper provides:
It is now widely acknowledged within the oil and gas industry that operational (production) pigging is a key frontline O&M activity for controlling internal corrosion in upstream production pipelines. Within MACAW we are at the forefront of this battle, helping operators with the development of corrosion management strategies and in the implementation of effective corrosion control schemes.
In this technical paper we provide a Corrosion Engineer’s perspective on developing corrosion management systems for oil and gas pipeline assets, highlighting organisational and technical challenges and the importance of operational pigging (i.e. utilisation of production pigs and ILI tools) and how this fits within an overall corrosion management strategy. More specifically, for the most common internal corrosion threats, we discuss possible mitigation strategies and their implementation (e.g. the identification of correct pigging tools and treatment frequencies for the application of biocides to control microbiologically influenced corrosion).
Based on actual results obtained through assessments and investigations conducted on a wide range of pipelines, the impact and effectiveness of typical current operating practices are critically reviewed. Suggestions and recommendations are then put forward for discussion with regard to improvements and/or alternative pigging strategies which may be beneficial in combating a range of different internal pipeline corrosion threats.
Intelligent inline inspections (ILI) are widely used to guarantee a safe operation of pipelines. The inline inspection provides reliable data in an economic way. Ultrasonic (UT) is currently the most accurate and reliable In-Line Inspection technology available in the market. These UT ILI Tools record data while travelling through the entire pipeline from Launcher to Receiver. In most cases, the Pipeline Operator does not need to make major adjustments to their pipeline. Nevertheless, pipeline operators may have to adjust medium flow rates to accommodate optimum inline inspection conditions, e.g. down to 1m/s.
NDT Global recently introduced the latest generation of UT tools - EVO SERIES 1.0. This generation offers highest inspection velocities of up to 4m/s. This high speed tools overcome reduction of flow rates for intelligent inspection runs. In addition, highest axial resolution available at the market (0.75mm) and circumferential resolution of 4mm provide excellent input for accurate pressure calculations, e.g. based on Riverbottom and crack depth profiles or even 3D Finite element modeling.
The authors will present basic background information about ultrasound inspection technologies. Theoretical aspects of EVO Series 1.0 tools are discussed for crack and wall thickness inspections followed by a case study performed in a real pipeline. Furthermore, EVO generation offers capabilities of combining different technologies in one tool. One single inspection tool with corrosion and crack transducers enables pipeline operators to operate their system safe with a minimized impact while inspection.
Nearly half of the world`s oil or gas pipelines have until recently been considered “un-piggable”.
This term is used when a pipeline cannot be inspected with a free-swimming in-line inspection tool without a need to modify the tool or the line to be inspected. Typical examples are for instance missing launching and receiving facilities, diameter variations, tight bends, low pressure and flow conditions or high pressure and high temperature environments, onshore or offshore.
In this paper the typical issues regarding the inspection of challenging pipelines will be discussed. A new concept will be introduced, the so-called “toolbox approach”. The driving idea behind the concept is based on having a large variety of services with all the required technologies, including magnetic flux leakage (MFL), eddy current or ultrasound, enabling tailor made solutions to be packaged utilizing exactly the right technical resources for a specific inspection and integrity challenge.
But it is not limited to a technology perspective. It also uses market information to identify mid- and long term market needs as well as special operational procedures.
In addition it must be stated that this type of work relies heavily on the expertise and experience of the crew involved, because of the often extremely complex boundary conditions and operational parameters encountered during the job performance.
Several case studies will be presented to illustrate this approach and address the major issues of successfully inspecting pipelines previously considered “unpiggable”, with a special focus on accessibility, negotiability and propulsion.
To effectively and regularly pig pipelines, a versatile technology is required that could be seamlessly implemented with the ability to navigate variable geometry all whilst being both operationally and cost effective.
Pipelines are the carriers of high value materials, critical to the success of the operation. Pipelines and pipe networks new and old, multi-bore and straight require care and maintenance to ensure that they are kept in good condition for fulfilling the aforementioned purposes. Collections of unwelcome bodies and /or restrictions to flow can prove to be very dangerous to the surrounding environment.
Aubin has developed EVO-Pig which alongside Pipeline Gels help remove unwanted bodies and debris from pipelines, ensuring flow conditions are optimised, maintaining production and pipeline integrity. EVO-Pig is a low cost option when compared to traditional mechanical pigging operations. Combined with the simplicity of the design premise and ease of operation, the technology offers a low risk option to pipeline pigging. Shape memory technology, enables the hydraulically or pneumatically driven flexible pig to easily move through changes in pipeline diameter and bends in the pipeline with the added benefit of not needing to be received.
After many years in development, Discovery™ subsea pipeline CT (computed tomography) technology is now fully operational and field proven, having successfully completed hundreds of subsea pipeline inspection scans.
Discovery™ is externally deployed and can scan through any type of pipeline, including flexibles and pipe-in-pipe systems, and through any type of coating. The scan results provide high resolution tomographic images of the pipeline walls to 1mm resolution, as well as characterizing pipeline contents to determine the amount and type of deposits present.
The inspection is carried out online with no disruption to normal pipeline operations.
This paper will describe how Discovery™ is used to help in mapping a pipelines contents to assist with operational pigging, and also how it is used to verify and accurately size defects picked up during ILI campaigns.
Pigging tools for pipelines are typically dominated by cleaning pigs at one end of the spectrum and intelligent pigs at the other. The cleaning pigs are simple, low cost tools that are deployed by onsite technicians and pose little operational risk to the pipeline Operator. Their simple design and construction, especially with foam pigs, mean there is little risk of them getting stuck in the line, mobilisation costs are low and they can be deployment & retrieved with standard facilities. Intelligent pigs on the other hand are complex tools that need to carry the NDT sensors and electronics / power modules in a configuration that allows for optimum inspection capability while maintaining good Piggability. The use of Intelligent pigs require significantly more planning in terms of logistics and operations, the use of specialist personnel for deployment and the processing of data.
The impact to production and the cost of inline inspection is significant and subsequently ILI tools are only deployed in a pipeline ever few years so data can be infrequent.
I2i Pipelines have pioneered the development and integration of advanced electromagnetic inspection sensors onto conventional cleaning tools for the regular inspection of pipelines. The innovative pigs bring together the best capabilities of both types of tools, the ease of use, the low risk and the low cost of a cleaning tool design coupled with the advanced NDT sensors normally associated with more expensive ILI tools. The result is a fully capable range of inspection tool that can be deployed regularly by onsite engineers to inspect pipelines for corrosion and cracking, trend inspection data and capture any changing conditions within the pipeline.
This paper will look into the technical challenges, applications and operational advantages of deploying inspection technology with routine cleaning operations.
As older fields become uneconomic, technology improves, business models change, and offshore assets, such as platforms, cease to be productive and are decommissioned.
In many cases, the existing pipeline network around these platforms is repurposed or reconfigured to suit current needs. Productive wells can be tied in to the existing network, and unproductive assets can be bypassed. Although the platforms are most often specific in purpose, the pipelines are generalists by nature. And prolonging the life of this type of asset is almost always profitable.
This paper explores the consequences of decommissioning – as part of pipeline repurposing – through a series of North Sea projects involving pipeline isolation conducted over the last seven years.
The ILI industry still lacks a suitable inspection technology for CRA-lined pipelines, i.e. pipes with a mechanically bonded inner pipe of a corrosion resistant alloy inside of a ferritic steel pipe carrying the hoop stress. Neither the existing UT technology is able to inspect through the interface of a CRA and a ferritic steel component, nor is the current MFL technology able to sufficiently magnetise the ferritic steel pipe in order to inspect this type of pipe.
The current contribution investigates the possibility of Magnetic Eddy Current (MEC) to carry out such an inspection. A prototype internal inspection tool has been devised. Several types of sample defects have been produced into the ferritic steel carrier pipe as well as into the CRA-inner pipe. The defect types anticipate the integrity issues that an internal inspection tool would need to address. Several pull tests under controlled speeds have been carried out. The results are presented. Influences of tool speed, magnetisation level and eddy current parameter are investigated. Special attention is drawn to the distinction of different defect types.
The MEC technology was found to be a suitable inspection technique for CRA-lines pipes. This is achieved through several adaptations for this particular task. The particular challenges for the internal inspection of CRA-lines pipes are underlined. The technology may also fill other existing inspection gaps, like the inspection of heavy walled small diameter gas pipelines.
The use of high-bypass de-sanding pigs, either in isolation or in conjunction with traditional brush pigs, has been proven as an effective new method for mobilising and removing both waxy and particulate debris.
This case study will discuss the execution and findings of an operational cleaning campaign targeted at the removal of both waxy and particulate debris from an ultra-deepwater oil production pipeline in West Africa. The campaign utilised traditional brush pigs as well as high-bypass de-sanding pigs to remove debris for the purpose of reducing the risk of under-deposit corrosion.
The focus of the paper will be on the high-bypass de-sanding pig; its design, function and operation, and how it complemented the capabilities of more traditional brush tools.
The paper will describe the cleaning requirements and the tool types engineered for the operation, including the difficulties of design for the pipeline geometry and operating conditions.
The global market conditions influence the extraction of resources onshore as well as offshore, whereby particularly offshore exploration pipelines need to cope with high temperatures and pressures as well as products containing corrosive elements. This leads to potentially higher corrosion rates in a high temperature environment. Pipelines made of ferritic steels are susceptible to corrosion attack, especially if specific types of medium are transported in the line or the pipe is situated in a critical environment.
The industry is addressing this issue through various means, also including the development of new materials and pipe types. More and more corrosion resistant materials like stainless steel are used, e.g. duplex steels or different types of corrosion resistant alloy (CRA) pipes. Over the past 30 years thousands of kilometers of CRA pipelines are laid and there is still a growing demand.
However, in the carbon steel but also in the CRA layer different types of defects and/or features can appear, whereby the ILI technologies so far focus on carbon steel pipes.
This paper will give an overview of state-of-the-art ILI technologies to inspect mechanically and metallurgically bonded CRA pipes. The challenges for inspection of the carbon steel and the CRA layer, for different ILI technologies will be presented.
Verification of inspection results is a challenge to the industry. This is notable in situations of offshore pipelines which are a challenge to access and repair. It is essential that operators have accurate and reliable information on their pipeline condition to enable informed decisions with regards to maintaining and ensuring the ongoing integrity of their assets.
The case study presented in this paper is based on data collected on the condition of a large diameter crude oil pipeline which has undergone several in-line inspections, corrosion investigations and integrity assessments.
In order to verify the results of these in-line inspections and subsequent assessments, automated ultrasonic infield inspection results were utilised. A combined technology review and assessment was then completed to determine the accuracy of the measured metal loss features and corrosion rates identified by in-line inspection surveys.
This paper aims to highlight the results of this investigation and the subsequent benefits of utilising in-line inspection tools as part of an ongoing integrity management strategy.
There can be many flow assurance challenges that may result in reduced production through a production system such as paraffin wax, asphaltenes, salts & scales, sand, hydrates and corrosion products. The presence of deposits in a pipeline can lead to accelerated corrosion as well as restricting flow resulting in production rates that are less than the capacity of the system. In order to successfully inspect a pipeline using in-line inspection tools thorough cleaning of the line is required to avoid data loss during the inspection. In addition to the presence of deposits causing issues while the system is in production the presence of deposits can be problematic during decommissioning.
The first step in any cleaning operation is to gain an understanding where the deposits / restrictions are located in the pipeline along with the chemistry of the deposit. Once the amount and location of deposits are known a custom cleaning program can be developed to clean the pipeline.
The oil and gas industry worldwide is reliant on the long term reliability of pipelines, predominantly rigid pipelines as the safest and most efficient means for the transportation of hydrocarbons.
Pipeline operators need peace of mind that should a pipeline fail their processes and contingency plans are fully qualified and ready to respond to an emergency scenario.
There are two distinct damage scenarios that need to be considered, the first is operational damage caused by corrosion or erosion. This damage tends to occur slowly over a long timescale so regular inspection of the pipeline can monitor the condition and ensure planned maintenance is carried out.
The second damage scenario is through external impact, caused by an anchor drag, dropped object or landslide. With this scenario there will be no warning and the damage could breach the pipeline, introducing an unpiggable bore restriction at minimum or stopping pipeline flow completely.
This presentation will discuss recent advancements in isolation technology which have been developed to enable the installation of safety critical double block and bleed isolations when an unpiggable midline defect exists.
Significant savings can be achieved by having the required equipment ready for deployment in the event of a pipeline failure. The primary objective of an Emergency Pipeline Repair System is to facilitate a rapid and safe repair ensuring pipeline production can be resumed as soon as possible, minimising environmental and commercial impact.
The presentation will include a case study featuring STATS supply of emergency response isolation plugs from 32" to 38" developed for Qatargas. These fully engineered isolation systems were designed and manufactured to meet the clients specification and are now maintained in a state of readiness close to the operator’s asset, to ensure rapid response to an emergency repair.
Internal long axial corrosion is the most common corrosion type in offshore crude oil and water injection pipelines. It has frequently a complex shape that ranges from a smooth uniform wall thickness reduction to a rugged surface with varying depths.
Long axial corrosion anomalies can be reliably detected and sized by means of ultrasonic in-line inspection (UT ILI). The rough surface of the corrosion can lead to outliers in the gathered ILI data. Accordingly, an elaborated filtering and re-processing of the inspection data is crucial for a consistent data assessment.
The inspection report usually provides maximum anomaly dimensions (total length, peak depth, etc.) and does not sufficiently describe the complex shape of corrosion anomalies. Therefore, methods based on corrosion depth profile (river-bottom profile, RBP) have to be applied for pressure capacity assessment. In addition, corrosion growth rates are ideally obtained by comparing RBPs of consecutive inspections.
This paper outlines the main results of a recent joint industry project that provides guidance to the assessment of long axial corrosion based on UT ILI results. It involves the determination of RBPs, the calculation of the safe operating pressure, the determination of corrosion growth rates and the extrapolation of the future pressure capacity. Compared to other assessment methods which are also based on RBP, the presented assessment approach accounts for a higher probability of failure associated with a higher number of corroded sections in a pipeline.
Chevron North Sea Limited (CNSL) operates more than 25 pipelines across three operated assets in the UK North Sea – Alba, Captain and Erskine.
Processes adopted by CNSL for effective management of pipeline integrity and reliability include a combination of online data collection, fluids sampling, corrosion risk assessment, remnant life modelling, and physical inspection techniques for the measurement of pipeline condition.
This paper discusses the input that in-line inspection (ILI) can have into an overall pipeline integrity management strategy. The following key points will be discussed: The importance of combining knowledge relating to active corrosion mechanisms together with an understanding of the capabilities and limitations of available in-line inspection technology. How ILI results can be used to review the effectiveness of corrosion management strategies and support remaining life assessment. How to select an appropriate re-inspection interval.
Case studies will be used to provide a practical insight into how this is achieved within CNSL.
Pigging operations often present monitoring challenges that are difficult to predict prior to launch. These include confirming launch, monitoring pig progress at strategic locations and confirmation of the pig’s arrival, often under adverse conditions. Accurately locating a stuck pig as well as quantifying the associated debris transported into the receiver can also be problematic.
Using a combination of different non-intrusive pig monitoring, signalling and data communications equipment, an operator can mitigate against these risks for even the most difficult or lengthy pigging operations.
Drawing on experiences gained throughout a diverse project history, this paper provides insights into reliable and novel monitoring methods available to an operator engaged in pigging operations. Descriptions of real life projects utilising using a variety of non-intrusive technologies will be discussed.
This paper focuses on the technology and logistical challenges for a long-distance, deepwater pipeline precommissioning and inspection project.
Weatherford Pipeline and Specialty Services (P&SS) performed this work on behalf of Noble Energy Inc., a major oil and gas exploration and production company. Its subsidiary, Noble Energy Mediterranean Ltd., contracted directly with Weatherford P&SS as part of their development of a subsea gas production and transportation system connecting the deepwater Tamar Gas Field to an offshore receiving and processing platform linked to the existing Mari-B Platform in the Mediterranean sea.
Gas production from the Tamar Reservoir is designed to occur through five high flow rate subsea wells into the subsea gathering system, which consists of an infield flowline from each well to a subsea manifold. From the subsea manifold, dual subsea pipelines will transport Tamar production approximately 149km to the Tamar Offshore Receiving and Processing Platform where the gas will be processed. The processed gas will then be delivered to the existing Ashdod Onshore Terminal (AOT) for gas sales into the Israel Natural Gas Line (INGL) system.
The inspection of pipelines through high levels of coating remains a challenging task. In particular offshore pipelines often require a thick coating for various purposes. Usually it is a combination of mechanical impact and corrosion protection. Hence the configurations can be quite different. The external inspection of subsea pipelines and risers often complement or substitute an internal inspection by pigging.
An overview of available technologies is presented. The limitation of the technologies and their physical origins are discussed. A systematic investigation in improving the capabilities was done. Most of the principles are based on some kind of eddy current technique. Several case studies of inspection through a thick coating are presented. In one case risers had to be inspected through as much as 12mm of coating and with a wall thickness of 25mm. The high stand-off measurement usually conflicts with a high resolution of the scanned surface. Metal loss defects as small as 10 mm and as shallow as 10% have been found. In a different project a wire disorganisation of a flexible pipe had to be detected through a coating of 9 mm. In this case it was possible to show, how a regular signal pattern and its distortion by defects can lead to a sensitive detection of defects through a coating.
In the last 4 years more than 800 inspections have been completed on & off-shore with the latest generation MFL ILI technology, capturing information on tens of thousands of kilometres of pipe, and generating a significant volume of dig verification data.
In collaboration with Oil & Gas pipeline operators around the world this growing dig verification database has been utilized to improve software models, algorithms, & analysis processes to validate and further enhance system detection, sizing, & reporting capabilities.
This paper focuses on the recent collaboration between ExxonMobil and PII, to investigate system capabilities with respect to “Pinholes”, to address a known threat to a specific pipeline in the United Kingdom.
This paper will describe the:
Internal corrosion can lead to production reduction as corrosion by-products accumulate in the pipeline and, in the event of a through-wall failure, can cause extensive hazard to people and damage to asset and the environment.
Corrosion inhibitors have proven to be very effective at reducing the overall corrosion rate when added to the pipeline product in small amounts. The inhibitors are generally introduced into the pipeline by injection, either as slug treatment or continuous injection, or most commonly as batch treatment employing a chemical column between two pigs.
Operators are looking for alternative treatment options. This may include the application of corrosion inhibitors by an innovative “spray pig” technology.
Mechanical interlocking products guarantee strict adherence to procedure and thus avoid human error. They are particularly useful for operations that are generally recognized as highly dangerous, such as pigging. Interlocks are a cost-effective measure that results in extremely high safety levels.
Traditionally however, interlocks function as independent and stand-alone safety systems. But as advanced digital technology now enables us to combine process control and safety instrumented functions within a common automation infrastructure, wouldn’t it be better to integrate operator procedures, such as those safeguarded by mechanical interlocks, with the Distributed Control System (DCS) and Safety Instrumented System (SIS) as well?
As the overall infrastructure in the oil and gas industry is aging there is an increasing demand to assess the integrity of all existing assets. As a result pipeline inspection using In-Line Inspection (ILI) tools has become the standard for pipelines that can be considered piggable. Many of the world's pipelines were however never designed to be pigged, the so-called unpiggable pipelines.
To operators these unpiggable pipelines are equally important to the overall integrity of the pipeline system and suitable inspection solutions are therefore required. Although alternatives like direct assessment and spot checks using in-field, non-destructive testing exist, the most valuable information can only be obtained from the inside of the pipeline using in-line inspection devices.
Typical challenges involve access (no pig traps installed), operating conditions as well as the pipeline geometry. Due to the individual challenges arising from pipelines deemed to be unpiggable a wide variety of tailored solutions has been developed in recent years.
One of ROSEN's recent developments is the extremely short Bi-Di Inline-Inspection tools. Their bi-directional design, passage capabilities and wide range of operating conditions provide great flexibility to operators, thus minimizing the operational impact and required pipeline modifications. Applications include ILI of tanker loading/unloading pipelines, gathering pipelines, branch connections, risers and flare lines.
This paper will discuss the continued development of ILI solutions specifically designed to close the gap between piggable and unpiggable pipelines by discussing their challenges, practical application, case studies, and the future of additional research and development.
In 2005, Total were planning to carry out an inspection of two 32” gas and condensate pipelines running 92 km from the South Pars field in the Persian Gulf to the shore terminal at Assaluyeh in Iran. The pipelines were overdue for inspection but it was known that hard scale deposits were present in the line which would present significant difficulties to the passage of either MFL or Ultrasonic tools. Total were therefore planning to carry out an acid clean of Sea Line 1 to remove the scale prior to the use of the inspection pigs. Our company was asked if we could run a multi-channel caliper tool through the line to measure the thickness and the distribution of deposits and to provide the information to the pipeline engineers to allow them to optimise the acid clean. In due course we successfully carried out the caliper run and from the data, we were able to map of the distribution of the scale and an estimate of the total volume of the deposits. From this information, Total were able to determine the quantity of acid required and optimise the soak time to ensure all of the scale was removed. Following the acid clean, we were asked to return and run the caliper to confirm that all of the deposits had been removed. In fact when we did the run we found that some of the thickest deposits had not been removed so a mechanical cleaning pig was used to remove the remaining deposits allowing the MFL inspection to be carried out.
In 2006 we were invited back to carry out the pre-cleaning caliper survey of the second pipeline – Sea Line 2. Foam pigs had been run through this pipeline but no hard bodied pigs. We therefore offered a smart gauging pig to run in the line first to get an idea of the size and location of the major restrictions before running our caliper tool.
However, when the gauging pig was run, it was severely damaged and the rear disc stack was completely stripped off the pig and left in the line (Figure 1). Clearly the restriction in this line was much more severe than in Sea Line 1. Fortunately the pig had not been completely stuck in the line and by measuring the damage we were able to figure out the key design parameters of a caliper pig which should be able to get through the restriction in the bend at the bottom of the riser.
With help from the engineers at Propipe, a caliper pig was produced and much to our relief, it passed through the line without a hitch. Once again, data from the caliper run was used to produce a mapping of the scale deposits and this time the post cleaning caliper run showed that the deposits had been successfully removed.
Several of the world’s oil and gas facilities are experiencing aging production infrastructure. Operators are now applying greater focus to integrity management and more frequent inspections. Internal visual inspection is one method for the inspection of pipeline systems. Challenges exist with this method related to camera tools and receiving a clear image as well as performing swift inspections to keep disruption of production to a minimum.
When a major operator on the Norwegian continental shelf required effective inspection of several flexible production risers, it became apparent that the existing technology did not provide the required image quality and operational effectiveness. This lead to the development of an inspection camera tool that combines existing technology used for inspection of drilling risers and blowout preventers (BOPs) with a commonly used deployment vehicle (pig) design.
The tool enables single inspection runs to acquire digital images in a high-pressure environment. It incorporates high resolution, wide-angle 185/360° images, powerful lighting, and customized software with digital unwrapping and advanced digital filtering.
The tool body has a bidirectional pig design and is launched and controlled using a high-tensile-strength control cable. An effective stripper unit mounted on a regular pig launcher helps ensure a safe launch and control of the tool. The visual inspection tool is normally launched in clear fluid, but other driving media can also be used.
Within pipeline systems, this camera tool enables inspection for abnormalities, corrosion, coating, functions, and other features. Operators can use this technology to improve and expedite the decision-making process, leading to time savings, reduced costs, and increased offshore safety.
When it comes to a fast, non-intrusive, complete and meaningful inspection of an offshore pipeline in-line inspection (ILI) has been the method of choice for several decades now. However, not all pipelines, piping or other tubular structures can be inspected with in-line inspection tools (pigs). The method is usually limited to looping flow lines or export pipelines, specifically designed for ILI operation. The remaining structures are often summarized under the buzzword “non-piggable”.
The typical ILI viewpoint is to consider the piggability under either the aspect of pipeline design or pipeline operation. Typical piggability issues in pipelines under pipeline design aspects are launching/receiving facilities, bends, and internal obstructions. The other aspects are operations-related. ILI may be impossible due to too high/low flow, too high temperature and other. In both cases ILI solutions can still be conceived and realised by either changing the pipeline or by adapting the pig. The latter is the technically more interesting solution for service providing companies. ILI providers are busy in designing and already offer tools for multiple diameters, for bi-directional operation and tools with special insertion techniques. Also there are many solutions available that use a cable operated tool and/or a crawler type tool. Discussions on solutions for unpiggable pipelines usually focus on these types of solutions.
There still remains an area of inspection tasks that can be summarized under “Not at all piggable”. For either technical or financial reasons, a pig-like solution may still remain unfeasible. In some cases the involved technical risk may also convince the involved parties to refrain from any ILI adaptation. In these cases either key-hole solutions or external inspection may remain the only option. The distinction between a key-hole solution and a pig-based inspection can be made by the aim to reach a 100% coverage in the latter case. For other inspection types a lower inspection coverage is usually accepted.
Acoustic pipeline pig tracking, simply put, is the attachment of a battery powered acoustic pinger to a pipeline pig; the acoustic signal generated by the pinger travels through the pipeline and into the surrounding water and is subsequently tracked with a suitable receiver system.
Receivers consist of a hydrophone, essentially an aquatic microphone tuned to the frequencies of interest, and some sort of user interface which displays, or more often plays back downshifted audio of the ping.
The hydrophones attached to receivers can be either omni-directional or directional depending on the task at hand. For tracking from a surface vessel, omni-directional is often the obvious choice. However, when precise locating of the pinger is required, a directional hydrophone can be used.
The energy emitted by the acoustic pinger are acoustic tones, often only a few milliseconds long and outside the range of human hearing, typically between 10kHz and 40kHz.
Acoustic pig tracking itself is not a new field. For decades pinger suppliers have supplied pinger equipment to offshore pipeline construction companies and pipeline operators alike. These pingers, when properly mounted on pipeline pigs, have provided these basic offshore pig tracking functions.
Despite this list of strong positive features, acoustic pig tracking has a somewhat spotty record of reliability in the field. Over the years CDI has had the opportunity to speak with many of the end-users of acoustic equipment. Anecdotal end user experiences have varied widely, with some firms having good experiences and others having complete failures.
Some of the failures of the systems are no doubt due to a lack of understanding and training of the operator; user error. This is not uncommon when infrequently used systems are put into the hands of end users. However, user error cannot account for all of the failures experienced by otherwise competent operators. There are some subtle underlying technical problems with existing acoustic pig tracking systems.
Perhaps greatest among these is multipathing.
Despite the high success rate experienced with ultrasonic ILI tools, technological improvements are still required to help operators manage the integrity of an aging pipeline infrastructure: improvements in the Probability of Detection (POD), improving detection reliability under different pipeline conditions, increased ranges for pipeline operating parameters, and leveraging synergies from a Combo Wall Measurement-Crack Detection (WM-CD) tool in a single run.
In 2010, Weatherford Pipeline and Specialty Services (P&SS) commissioned its new generation fleet of ultrasonic wall measurement and crack detection tools. One of the design objectives was to address some of the ILI tool limitations identified above.
This paper focuses on reviewing the latest design improvements for the new generation tools and presents a case study on a recent survey conducted on the Adria-Wien Pipeline (AWP). The pipeline sections inspected were the 30" x 4 kilometer and 18" x 420 kilometer pipeline. This paper is a joint collaboration between AWP (represented by Michael Huss) and Weatherford Pipeline & Specialty Services.
In addition, a generic approach will be described for the development of complex off-shore applications that helps manage the technical & commercial risk for both operator & ILI vendor in delivering a holistic in-line-inspection solution.
This paper discusses the development of the dynamic speed control system, initial field trials, operational success and its application for maintenance pigging, intelligent cleaning, debris mapping, and black powder removal as part of an operator’s pipeline integrity management strategy.
Both gas and oil are exported via existing pipelines, the gas export being operated by Gassco and via the FLAGS pipeline to St. Fergus, and the oil via the Troll Oil 2 pipeline to Mongstad. This paper is about the oil export pipeline. Next year we will cover the gas export pipeline and how to pig it.
The tie-ins are to a vertical (or lateral) Wye installed at time of laying of the pipeline it ties into. At time of construction, the vertical Wye is typically selected, as it can be installed over the stinger of the lay barge, whereas alternative solutions can require a separate installation vessel.
The vertical Wye by itself would be piggable, but the challenge was created by introducing a dual diameter system together with a requirement for frequent wax scraping. Wax scraping in a dual diameter system had been done before, and passing vertical Wye was done before, but the combination was our challenge.
This paper describes how we solved the challenge and how we worked together.
However, although "Double Block and Bleed" is a universally used term to specify a level of isolation, the definition of the term is by no means universal.
When the concern is the inspection of a different type of pipe like flexible pipe, the task is completely different. Not only do the types of defects change, but so do the signals and the analysis procedure.
In the following external inspection of the layers of flexible pipe will be discussed.
Early experience with Pipeline Engineering’s cleanliness assessment tool suggests that the use of this type of tool can make a valuable contribution in allowing a reliable judgement to be made regardingwhen a pipeline has reached a state which will permit a successful intelligent inspection run.
Data is presented from a number of recent PECAT® surveys, demonstrating how the data recorded gives an objective measure of the progress of a cleaning operation, and allows an improved understanding of the internal state of a pipeline. Measurements of wax films down to a thickness of the order of 1mm have been made.
The river bottom corrosion, scale and the presence of a smooth bore flexible jumper in the middle of the pipeline system provided interesting challenges regarding pipeline cleaning prior to inline inspection.
This paper addresses the experience with pigging of water injection pipelines as well as pigging challenges that can be expected in the near future.
Modern advances in inspection technologies now allow for inspection and assessment of these previously unpiggable pipelines providing today’s owner-operators a varied range of inspection options. However, not only does each inspection methodology have its own related costs and benefits, but each option can have a significant and varied impact on the entire asset integrity program.
This paper uses multiple case studies to highlight solutions that have worked for individual operators. By examining the results of various inspection methods and detailing how inspection data is used for assessment and asset management, we can understand how inspection data ties into the larger decision making process.
The anticipated concerns of the flexible pipe operators are defects such as cracks, corrosions, erosion and fatigue in the different layers of the wires under various tensional stress levels. While the inspection techniques currently available in the market are able to inspect only the near side layers for wire disruptions, the far side layers remain uninspected.
Developed by Innospection, MEC-FIT™ is a Flexible Riser Inspection Tool using a patented technology that combines direct magnetic field lines with eddy current field lines, thus allowing a deeper penetration into the various armored layers. This technique enables the selection of the layers to be inspected, or alternatively allows the optimisation of the inspection for a specific layer from which a defect signal is received. The tool is capable of detecting defects such as cracks, corrosions, material fatigue and general wall loss.
Unlike traditional inspection methods, this system requires no couplant or annular flooding. Deployed from an ROV, the inspection data is transmitted in real time via the ROV’s main umbilical back to the inspection computer at the ROV control unit.
PII worked together with the client's team – over a 14 month contract period to establish a comprehensive understanding of the integrity of such an ageing asset and to support QP with the required integrity management tools to maintain the pipelines going forward. Comprehensive pipeline integrity management system (PIMS) software was implemented that was integrated with QP’s existing pipeline GIS and was aligned with current industry best practice to effectively manage and mitigate the principal pipeline hazards and risks
The phenomena were typically seen in wax rich pipelines. There were at the time no inspection tools on the marked that were fully suitable to be run in wax rich pipelines and at the same time collect inspection data over the whole pipeline length.
In most cases, the pipeline cleaning is the responsibility of the pipeline operating Company and such the inspection Contractors did not have any responsibility if the inspections failed due to wax settling on the ultrasonic sensors or the odometer wheels stopped due to wax.
This paper presents the work process taking place, from the first unsuccessful Ultra sound Testing (UT) inspection, resulting in a project to develop a UT tool solution which handles wax rich pipelines.
A new UT inspection tool was developed together with a supplier. The new technology have been utilised in several of Statoil’s wax rich pipelines with good results. Statoil’s experience from the utilisation of the new technology will be presented.
Conventional inline inspection (ILI) tools – commonly referred to as “pigs” – are frequently used to perform detailed inspections on pipelines. These tools are not designed for use on all pipelines, however. Valve restrictions, lack of launcher/receiver facilities, changing pipeline diameters, flow restrictions, or tight bend radii can deem a pipeline “unpiggable” if the inspection tool cannot physically pass through the line. Scaling up a pig for use in large diameter pipe is not as technically challenging as scaling down a pig for use in confined and restrictive pipe spaces. Until recently, little progress had been made in development of pigs for these circumstances, and consequently a large amount of piping, particularly within the fence line of refineries and other process plants, remained inaccessible.
In order to reach the universal goal of any in-line inspection (ILI) of reliably and accurately determining the state of the asset, two basic conditions must therefore be met. Firstly, by making allowance for the flow and pressure conditions within the line, a smooth and controlled tool passage must be achieved to ensure optimal data collection. Secondly, the inspection tool must be fitted with adequate technology to ensure that the specific threats posed to gas pipelines such as SCC and TLC are consistently detected. Provided that these two basic conditions are met, knowledgeable and experienced analysts can successfully overcome the specific issues associated with the in-line inspection of gas pipelines.
As the inspection method strongly depends on the type of pipe and the type of degradation mechanism, regular inspection methods are usually not applicable. This is the case for internal as well as external pipe inspection. It has been found that eddy current technologies are indeed a very versatile method to design tailor-made inspection instruments. It is a common misconception that eddy current is only sensitive to surface defects.
The paper will describe the advantages of eddy current inspection methods. Methods are classified to show that in fact the methods vary considerably with respect to their field of application. Three case studies are presented, where bespoke instruments have been designed to inspect pipe types that have previously been considered non-inspectable due to their unusual nature. Also it is described how methods that are currently used externally would be employed in an intelligent pig.
This paper will present the results which demonstrate the accuracy of the technique in detecting and locating blockages in gas pipelines. In particular the results of these tests will show how the technique was able to detect pipeline features with background noise.
In order to optimize the monitoring of Shallow Internal Corrosion (SIC), a new detection device has been developed on the basis of Eddy Current (EC) technology. The sophisticated SIC tool provides not only the determination of the corrosion status and growth rate, it also enables one to gain detailed information about the internal diameter and shape, such as ovality and dents. Shallow defects of even minor sizes are detected for assessing the degradation process resulting from internal corrosion.
Here, an introduction to the SIC inspection technology is presented.
An insight into, and some examples of, how design, construction and as-built records can help manage the risks associated with pigging and integrity management, how poor records create difficulties and uncertainties, and how ILI can tell you more about pipeline construction.
Approximately 60% of the world’s gas, oil and product pipelines can be inspected with off-the-shelf inspection tools. In the past the remaining 40 % of pipelines have often been classified as ‘unpiggable’. A large proportion of these unpiggable pipelines are offshore, multi-diameter lines, with low flow conditions and often with very challenging OD ratios.
Today, it is possible to develop individualized inspection solutions for multi-diameter pipeline systems. The development of such solutions can already be incorporated into the FEED process for these offshore structures. On the other hand, a great number of pipelines were constructed and laid in times when in-line inspection (ILI) was not available or not a requirement. Occasionally the passage of these offshore pipelines is restricted.
This paper presents the development of a series of 14"/18" ILI tools and their successful application survey in a 95 km long, high-pressure, heavy-wall, low-flow off-shore pipeline. In a team-effort between the pipeline operator (“Operator”) and the inspection company (ROSEN) a solution was developed for a challenging pipeline, which would have been considered ‘unpiggable’ in the recent past.
Pipesurvey International has developed a tool that can cover at least a bulk part of these pipelines. The XHR MFL tool incorporates all features of any up-to-date MFL ILI tool. The surplus value of the tool is that it is of complete bidirectional design, multidimensional and it has short bend-radius capability. The tool can be launched into a single-entry pipeline, be retrieved back at the same point and in the mean time inspect any length of pipeline. The tool is autonomous but can be operated with an umbilical as well. It is possible to combine the tool with a self propelling pipe robot, which takes the inspection range even one step further.
Intelligent pig inspection systems are important tools to manage the integrity of the pipelines. An intelligent pig survey enables the operator responsible for the integrity of the pipeline, to assess the failure risk due to metal loss corrosion using the findings of the inspection survey. However, not all pipelines can be inspected using intelligent pig technology, due to the pipelines origin. In addition the inspection results are not directly available during the inspection process and therefore important decisions can not be made until the inspection report has been issued in a later stage.
This paper discusses specific applications for offshore pipelines.
The paper will include an analysis of pipeline features that affect pigging tool selection and then go on to look at other variables that determine the pigging tool design; this will include a step by step guide outlining how the tool is designed, the development of prototype pigs and the importance of testing and validation prior to final deployment in operational pigging programmes.
The proper use of many of these methods can substantially reduce the costs of repair and maintenance programmes. Weatherford’s long experience suggests that most pipeline operators have their own well-grounded preferences for selecting methods to rehabilitate pipelines based on Fitness-For-Purpose assessments. As a rule, analysis of the current condition of pipelines requires that additional factors such as defect growth rate, interaction of adjacent defects, as well as pipeline operators’ specific requirements are taken into account almost all the time. The efficiency of defect assessment methods significantly increases when the results of two or more inspections are used. It has become desirable that the pipeline integrity assessment, which is a multi-stage process, would benefit from automation.
This paper describes Weatherford’s i-View℠ ILI software, which is the result of long experience of dealing with different pipeline operators.
Retrofitting pig launching equipment can also be extremely costly, particularly if the number of launches required are relatively few. There are also many cases where temporary launchers are required, yet these have even fewer available standards to work to.
International Pipeline Products Ltd of Catterick Garrison, UK have developed a solution that allows straightforward, temporary and cost effective pig launching and receiving for low pressure functions. Adding to the cost effectiveness of the product is the fact that the mechanism relies not on a pipe I/D but a pipe O/D, which, considering how it is usually the O/D that is constant in the pipeline to ensure standardised clamps and stands vastly increases the range of applications for each individual product across a pipeline.
In general these systems are set up prior to the pig run at which point signal frequency is selected relative to the type of tracking required. As a general rule a higher frequency is required to track pigs moving at a high velocity to ensure detection as the pig passes the detection unit. Lower frequency settings are utilized when a pig is to be monitored in a fixed location for a greater period of time. With the exception of radio active sources, battery life for the transmitters is almost directly proportional to the frequency of the signal hence a higher signal rate will reduce battery life.
The TDW SmartTrack™ system was developed to overcome the limitations of these systems by introducing through wall communication which allows the transmitter signal frequency to be modified externally. The result is greater flexibility during operations, particularly where these operations require extended monitoring over longer periods of time or where the unit can be put into sleep mode then re-awakened when critical operations re-start.
The units will also uniquely identify each passing pig in multiple pigging operations, log data such as pressure, allowing real time monitoring through the pipe wall.
Codes and regulations contain limit state criteria to prevent buckles from happening during construction and in service; however, there is practically no acceptance guidance. In cases when buckles and wrinkles are identified, pipeline operators seek expert opinion.
The current industry thinking and research supports the use of advanced assessment techniques (beyond the depth-based rules). These enhanced assessment techniques make use of the detailed profile of a geometry anomaly. Such information is obtained from high-resolution geometry tools and other supporting information on the presence and severity of stress risers from ILI tools.
This paper describes how strain-based and stress-based assessment of geometric anomalies can be utilized to assess their significance and need for remediation. Examples are discussed to demonstrate application of the enhanced methods for the assessment of buckles.
An in-line inspection tool capable of reading and recording the magnitude and polarity of current supplied by cathodic protection has been developed and tested in both crude oil and refined product pipelines. The results show that CP currents can be quickly, accurately and efficiently gathered without access to the outside surface of the pipe. For difficult to access areas, CPCM™ Cathodic Protection Current Measurement in-line inspection provides for a reliable, cost effective, time saving way to monitor, validate, or trouble shoot a pipeline’s cathodic protection system.
Over the history of pipeline operations, increasingly sophisticated techniques have been used to make measurements. Magnetic flux leakage and ultrasonic tools can be used to make measurements of wall loss, and other conditions. Caliper tools have been used to measure dents and other mechanical conditions. More exotic tools have been proposed from time to time. All of these techniques make a big contribution to allowing evidence-based decisions on the maintenance and rehabilitation of pipelines to be made.
It has been recognised in the industry that direct measurement of stress in pipelines could be a major tool in toolkit used for pipeline condition assessment. In the relatively recent past, the only reliable means to measure stress were either destructive, or non-portable. Advances in the understanding of magnetic properties of metals, and their relation to stress have allowed a number of potential measurement techniques to be proposed. Many of these have been based on the Barkhausen effect, but other concepts, such as non-linear harmonics have also been investigated.
Weatherford’s Pipeline and Specialty Services group, working with ESR Technology, are in the process of developing a pig capable of measuring the absolute biaxial stress in pipelines, based on ESR's proprietary MAPS measurement system.
Today, many pipelines and the connecting risers are piggable and with the intelligent In-line inspection (ILI) tools flaws can be detected to monitor integrity and fitness-for-purpose. Different types of tools are needed to cover all possible flaws, such as metal loss, cracks, geometric anomalies and leaks. Nevertheless, despite all kind of measures, the riser is still a difficult section for inspection as it may have a very thick wall thickness or other obstructions, thereby reducing the effectiveness of such ILI tools, also their speed in risers is difficult to control.
This presentation focuses on the “unpiggable” risers where free swimming ILI tools cannot be used or are of limited use. Application of internal tethered ultrasonic tools is discussed for inspection of both crude oil and gas risers. Besides that, in the second part of this paper, also non-intrusive methods will be shown as a valid alternative to inspect risers and pipelines from the outside, even without removing marine growth. Today this can be done even at -200 m using ROV’s.
The presentation shows that each tool has a dedicated field of application. Operational aspects as well as expected results will be discussed, they are of benefit for all operators of platform risers in the oil and gas-industry operated in the North Sea and world-wide.
Previous papers have discussed how to manage an inspection project, and have given guidance on understanding the inspection report. In this paper we will look in more detail at the assessment of corrosion defects reported in a pipeline by an intelligent pig inspection, and, in particular, large defects or groups of defects.
At this point it is important to draw a distinction between:
These are two separate tasks: the first is carried out by someone who is familiar with the inspection technology and understands what the recorded data (voltage levels for coil sensor MFL tools, or time delays for ultrasonic tools) indicates in terms of pipe wall metal loss or other possible features; the second requires an understanding of how pipeline defects are caused, and how they behave when subject to internal pressure or other loads.
Pipeline bending can have regional or local character. Both defect classes can be detected and analyzed with specific in-line inspection modules. The latest geometry sensors developed by ROSEN can be combined with proven inertial navigation systems. This combination improves sensitivity, repeatability and confidence when detecting pipeline bending strain while also taking into account the influence of strain around ID anomalies.
Repeatability is important to establish the reasons for increasing strain values detected at specific pipeline sections through in-line inspection surveys conducted in regular intervals over many years. Moreover, the flexibility resulting from a combination of different sensor technologies not only makes it possible to meet specific operator needs but also provides a more complete picture of the overall situation.
A HAPP consists of a brake unit, a seal unit and a cleaning head. The brake unit ensures that a pressure difference develops over the seal unit and the fluid transported in the pipeline is transformed into high-pressure jets cleaning the pipeline inner wall.
This highly efficient technology has great potential to be employed for numerous non-standard pigging jobs. As a consequence it enables pipeline operators to save capex and opex today required for complicated pigging programs.
In addition, advancements in electronic design have led to marked enhancements regarding axial and depth resolution. Combined with higher speed capabilities than previous generations of ultrasound tools, this has significantly extended the range of application, offering quantitative and high accuracy data for defect geometries not previously covered.
This paper will focus on and discuss the issue of resolution.
This paper describes a range of application focusing on the time and cost saving achieved by the operator whilst minimizing environmental impact.
In recently years, a number of companies have investigated techniques intended to utilize the dependence of the magnetic response of ferrous materials to applied stress in order to make direct measurements of stress. Most of these techniques have been based on the Barkhausen effect, but measurements based on other phenomena such as non-linear harmonics have also been looked at. This paper discusses the use of an alternative technique based on other magnetic properties that have been shown to allow derivation of a quantifiable relation between the level of stress present in material and the magnetic response. This technique, named MAPS by its developers, ESR Technology, has been employed with considerable success out-with the pipeline industry.
Weatherford Pipeline and Speciality Services are presently working with ESR Technology in order to develop a pig-based inspection tool utilising this measurement technology. The initial aim is to provide a tool capable of diagnosing pipeline problems due to ground movement, spanning and other cause of bulk changes in stress. Refinement of the technique may make it possible to detect local increases in stress due to the presence of dents, metal loss defects etc.
Having as much knowledge as possible about assets and their pipelines and knowing how to analyse this information has become very important. In offshore pipelines intelligent pigging provides the clearest picture of the integrity of the pipeline. The information from these inspections can then be fed into the many assessment tools available in the market, for example:
The result of an intelligent pig inspection is an inspection report with a list of defects. To gain the full benefit from an inspection the pipeline operator must understand the inspection process, and what the list of defects means for the immediate and the future integrity of the pipeline.
Tool validation is a difficult task requiring detailed field measurements of features in a format that can be compared directly to the ILI data. This paper presents an overview of the validation process and describes the development and testing of a new device for measuring, documenting and assessing external corrosion on steel pipelines.
Feasibility and design of the new system were funded by the U.S. Department of Energy through the National Energy Technology Laboratory.
A great deal of work has been done on extending pipeline life by developing inspection technologies such as intelligent pigs, methods for recoating pipelines, techniques for internal painting, and hydrotesting regimes that will detect critical cracks. This wide range of options, the potential for problems such as a stuck pig, the costs associated, and the potential consequences of a failure, mean that a pipeline operator has to proceed very carefully when planning any inspection programme.
This paper will consider pipeline inspection based on the authors experiences from recent projects and recommend a simple strategy to ensure that a sensible, justifiable, plan is developed.
In a final stage the data of high-resolution ultrasonic inspection tools can be used to compare defects on a basis of wall thickness C-Scans. This will generate more precise conclusions about corrosion growth on single defects, which was not possible on the traditional statistical approach.
Major parameters to consider are wall thickness, length, requirements regarding resolution and accuracy and more and more the ability of the inspection tool to negotiate diameter variations.
This paper will provide an overview of available technologies and in-line inspection tools for the inspection of dual- and multi-diameter offshore pipelines. The paper will cover in-line inspection tools based on ultrasound-, magnetic flux leakage- and laser-based technologies covering geometry-, metal loss- as well as crack detection.
Pipeline pigging has a significant role to play in meeting these conditions, and pigs are met with in a number of guises during pre-commissioning operations. This paper is intended to provide an overview of the uses of pigs in these operations, and provide some basic information on train design and pig selection. Some examples are drawn from a range of types of construction and pre-commissioning projects in order to give a feel for the practicalities of the operations described.
BP Pipelines NA encouraged cooperation between all parties involved in the integrity process to adapt reporting requirements and work procedures to provide the best available information for integrity analysis and to ensure continued improvements. This cooperation is a key part of the integrity equation and essential to a successful program.
This paper presents an overview of the validation process undertaken on a 51 km (32-mile) section of 457 mm (18-inch) pipeline. This pipe section was inspected in 1999 and again in 2003 by the same inspection company. This provided an opportunity to evaluate improvements in inspection technology, assess repeatability of performance and develop an engineering based approach to review, analyze, and validate high-resolution metal loss MFL data. Field verification and data validation included the use of several NDE techniques to acquire field measurements to overlay and compare to the ILI inspection data.
Anomaly classification and distribution is examined and methods of selecting validation locations for future inspection developed. In addition to the primary goal outlined, the 2003 repair program provided an opportunity to evaluate the performance of the composite sleeve reinforcements applied in 1999, after 4 years of service.
In a final stage the data of high-resolution ultrasonic inspection tools can be used to compare defects on a basis of wall thickness C-Scans. This will generate more precise conclusions about corrosion growth on single defects, which was not possible on the traditional statistical approach.
Most internationally recognised repair codes such as ASME B31.4 and B31.8 accept the use of composites for this repair function.
Most oil and gas pipeline operators are familiar with composites and the health, safety, technical and commercial benefits they provide.
The purpose of this paper is to introduce new areas of repair applications where composites can be used and to provide case studies for these particular repair functions.
This paper will focus on some emerging issues relating to pipeline pigging operations in three specific areas; pigging pipelines under low flow conditions, pigging pipelines to control/mitigate MIC corrosion and new technology opportunities.
The new intelligent plugging and pigging tools allow remote local pressure isolations at any water depth and at any position along a pipeline. The remote through-wall communication system reduces the number of vessels required during the flooding and commissioning of pipelines since pigs can communicate wirelessly their arrival and departure through the pipewall, through water and through air.
This paper presents the remote controlled pipeline isolation and pigging tools and describes the function and operation of each main sub-system. The paper presents historical applications with focus on subsea and midline pipeline isolations and interventions.
The method employs two tethered crawlers, one located close to the lay barge end and the other beyond the point where buckling is expected to occur. The tractors can "walk" in synch along the pipe. As both tractors are self-propelled, this proposed new method will remove the need to have a cable in tension. By fitting the second tractor with a camera and an array of sensors, video images and geometrical measurements of the newly laid pipe can be obtained in real time.
This paper focuses on selected areas of the TRACERCO Diagnostics™ technologies that are used for pipeline deposit measurements, specifically their location, amount, and profile within any length of pipeline.
This paper will show how the techniques are employed, the type of results that are achievable, and describe selected case studies.
It is evident that integration of data into a single, coherent data management system can provide significant benefits. However, the cost of implementing entirely new systems - with intensive data capture programs - is difficult to justify given the earlier investments. As a result dedicated risk management software using static and separately maintained data is often used as a quick, low cost alternative to meet regulatory compliance commitments.
Experience has shown that, with the right technology and an understanding of the specific needs of an organisation, a phased approach to integrated data management can be achieved at minimum initial cost by exploiting legacy data. This provides a low cost yet scalable solution that can grow with the changing needs of the business.
In addition to the benefits of legacy data integration, we will also look into the benefits of technologies for distributed data access to provide simple, process-focussed reporting tools.
SAAM® Smart Utility Pig technology has been deployed in these respects over the past 7 years in over 7,000km of pipeline. Over this time, the technology and analysis techniques have been developed, taking into account the experiences gained from previous surveys. This has led to recent improvements in the technology and increased confidence in the analysis results.
This paper describes the various capabilities of the smart utility pigging technology, giving examples from recent pipeline inspection surveys. These applications include: providing a vertical and horizontal pipeline profile, and using the results to monitor for movement or to assess pipeline strain; identifying mechanical damage, including bore restrictions, dents, illegal taps or offset couplings; providing an assessment of pipeline debris, estimating the remaining internal bore and determining the effectiveness of the pipeline cleaning program; and providing an assessment of internal corrosion.
The paper concludes with a brief description of special projects where the technology has been integrated with external sensors to provide additional information during a pig run, and a discussion of possible future improvements in the technology and data analysis.
The methodology involves assessing and weighting the effectiveness of nine key integrity activities:
Attention is also given to the cost of the Integrity Management activities. The benchmarking methodology identifies cost optimisation opportunities whilst maintaining acceptable safety levels.
The methodology has successfully been utilised to benchmark 140,000 km of pipelines worldwide and details are provided.
Knowing this, in-line inspection of the pipeline has to be applied, and before such inspection is executed, the line has to be clean. During the above mentioned Conference there was concluded "The cleaner, the better"!
So, the deviated topic for this presentation is "The cleaner, the better" and the central question during the whole presentation is "do pipelines need cleaning?" After the presentation, all of you could answer this question and I already know what it will be.
|Total Cleaning||>>||the right conditions for in-line inspection|
|In-line Inspection||>>||correct readings and data collecting|
|Pipeline Integrity||>>||Interpretation of the data, resulting in acceptable or not|
|Safeguarded Production||>>||Operator/owner can anticipate on the future in time!|
Every day there is a considerable amount of time and money spent on making mechanical pigging runs in pipelines, typically they are run for more than one reason:
By adding special fluids to this process, the effectiveness of these runs can be enhanced:
This paper will discuss the typical pipeline pig's design, this includes the different shapes of the components and materials used relate to the performance of the pig as it makes its journey through the line. Various limitations of pigs will be outlined due to their physical design versus the geometric shape of the surface to be cleaned. The limitations of commonly used solvents will be discussed along with what is required to make cleaning fluids more efficient.
This paper focuses on selected areas of the TRACERCO Diagnostics ™ technology as applied to Pipeline Inspection and Flow Assurance.
Customer problems were reduced to a set of functional requirements and through attention to detail monitored via an ISO 9001:2001 Quality Management system a solution to the particular problem is reached.
In the instance of the CMSS it was resolved early on in the design procedure that a new and revolutionary approach had to be adopted if the functional requirements were to be met whilst at the same time upholding the philosophy of FTL.
The majority of previously designed commissioning pigs adhered to well established design concepts in that all functions of the pig could be met with a relatively simple low cost design. The Åsgard multi diameter gas transporter line however was totally different.
The pipeline length would be 710 km at 42" diameter and the last 500 metres would reduce to 28" diameter. Drive disc and support disc wear would be a critical consideration.
By applying basic hydraulic cylinder design principals FTL decided that contrary to previous designs the support function of the pig should be completely separate from the sealing and drive function. Due to the expected high rate of wear that the sealing discs would have to withstand it was decided to take the hitherto unprecedented step for a commissioning pig to mount the whole unit on a self supporting and self centering suspension system.
By careful design and incorporating variable suspension geometry the potential to overload the wheel assemblies was avoided when passing from the larger to the smaller diameter pipeline sections. Furthermore, a slow controlled rotary motion would be imparted to the whole pig train to even out the wear on the discs.
This generic term can in some cases cause confusion, and the PPSA (Pipeline Pigging and Services Association) has endeavoured to be more correct and specific.
The paper presents current technology and describes the advantages and disadvantages of the various designs of dual diameter pig in the market. It also goes into detail of the function requirements of pigs and the validation process, which should be undertaken, prior to using a pig in a real life pipeline.
After a short summary of flaws and defects found in steel pipelines, the various physical principles utilised by intelligent pigs will be introduced and specific strength and weaknesses will be discussed.
Geometry, metal loss survey, crack detection and inertia tools will be introduced. Especially ultrasonic in-line inspection tools for wall thickness measurement and crack detection will be covered, regarding technology, vendors and defect specifications.