PIGGING PRODUCTS & SERVICES ASSOCIATION
Tel: +44 1224 398801, Fax: +44 1224 860644
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The seminar presentations will be given by PPSA members, all experts in their own field.
Inline inspection campaigns can cost many hundreds of thousands of pounds to perform, whilst an unsuccessful pig run can cost an Operator significantly more. This is especially true for subsea pipelines where access is restricted, and remediation is complex. In order to help reduce this risk, many Operators chose to use pig tracking systems as a standard component in any pig run.
Tracerco’s proven pig tracking system has recently been involved in a successful inspection campaign on an extensive pipeline system. The pipeline was known to have a history of deposits and bore restrictions which had the potential to impede the inspection run. By using Tracerco’s pig tracking system, the Operator was able to accurately monitor the pig passage even through changes in the pipeline’s design.
This paper will outline the challenges facing the Operator which led to them choosing Tracerco for their pig tracking services, through the project process to the conclusion of the project, including NORM services.
Part of integrity management, pigging is performed as a standard, regular operational activity throughout the pipeline network’s lifecycle. Pipeline operators have been running pigs successfully for years. However, every so often, a problem occurs and a pig becomes stuck, stalled or damaged in the pipeline.
When another service provider’s bi-directional pig became caught up in a production tee during routine operational pigging, the operator of a 240-km, 28-inch gas export pipeline in southeast Asia contracted T.D. Williamson (TDW) to recover it.
Fortunately, the pig had stopped half way into the tee and was not blocking production flow entirely. However, the concern was that the pig could move further into the line and completely obstruct production flow, leading to shutdown of production gas.
After considering multiple options for recovering the bi-directional pig, the operator, together with TDW decided to use mechanical means. TDW designed, manufactured a bespoke recovery tool then tested it in a mock-up of the launcher and tee that replicated the stuck pig scenario. This enabled a successful pig recovery operation offshore.
This paper describes the steps taken to execute the pig recovery, including planning, site visit, engineering, tool manufacturing, testing and execution.
Pipeline blockages caused by scale, wax build-up or hydrates can sometimes be removed by non-invasive techniques, such as chemical treatment or pulsed blockage removal technology. Some pipeline blockages may have been caused by normal operational pigging or more likely due to cleaning operations prior to inline inspection (ILI). Recently we have become aware of several ILI tools causing partial or complete blockage of the pipeline.
When non-invasive techniques have proved unsuccessful or unsuitable then a more invasive blockage removal intervention may be required. The less invasive method of blockage removal would be to inject and flush locally, via small bore hot taps through a dual seal, self-energised, lightweight strap clamp.
If the blockage cannot be removed by local flushing / chemical injection, then the blocked pipeline section may need to be completely removed and replaced. If a temporary bypass is installed, production can be resumed while the blockage removal operations are executed. This short presentation will explain how type approved double block and bleed hot tap installed isolation tools enable the safe removal of the blocked section while the pipeline is at operating pressure.
Animations and footage of recent subsea pipeline intervention projects will be used to highlight the applications of these techniques.
3P Services' affinity to inspect difficult pipelines was one more time put to test, as one of their clients experienced a stuck pig situation in a 3” condensate pipeline. During the first inspection of this pipeline, the MFL tool of another vendor lodged in a river crossing section and stayed there for seven years. Using non-standard methods, the client achieved to recover the tool and considered the pipeline as unpiggable for several years. In addition to the lodged tool event, flow conditions, length and abrasive internal surface were factors in this determination.
However, 3P Services’ had previously achieved success for another division of the same client in developing a 2” MFL tool, which was a basis of trust in 3P Services’ technical capability. 3P Services was able to build special 3” MFL and GEO tools capable of traversing the entire length of the line.
Low flow operating conditions required increased sealing capability and at the same time reduced friction between the tool and the pipeline. Other challenges included the very long run time and tracking the tools through swamp and jungle terrain.
There have been significant advances in magnetic flux leakage (MFL) in-line inspection (ILI) technologies in recent years. These have led to improvements in Probability of Detection (POD), Probability of Identification (POI) and Probability of Sizing (POS).
Whilst often the main focus of these advancements is the inspection vehicle itself, the end product of an inline inspection service is reliable and accurate data. This end product is influenced by various technological factors which include: recognition and detection algorithms; complex sizing models; robust and rigorous processes and highly trained and skilled data analysts.
This paper explores all the main factors that contribute to delivering the reliable and accurate inspection reports that pipeline operators demand today. This review will be supported by extensive comparison of ‘as reported’ data vs ‘in ditch’ findings. This is particularly valuable for operators of offshore pipelines, where proving ILI performance is at least challenging, and often not possible.
Data from cleaning pig runs with data logger has been combined with operational data i.e. flow rate and pipeline information e.g. joint length. Main parameters from the data logger are acceleration in three directions, differential pressure and temperature. From the data wax deposition zones can be estimated and pig speed for each pipe joint can be calculated. By comparing the calculated joint speed with calculated speed based on bypass, it is possible to conclude if the bypass set up has been fully open during the run. This information is a useful input to the wax cleaning program. The analysis is performed in MATLAB partly with MATLAB software partly with in-house written software.
Cracks and linear anomalies are common threats in the pipelines. The origin of these features can be caused by manufacturing related processes or they can appear during operation.
ILI inspections use techniques such as EMAT or Ultrasonic Shear Wave following the principle of Pulse-Echo to detect and size these anomalies. However, such techniques have limitations in detection and sizing when the features are not radially oriented. Features that do not fulfil this condition can be considered complex, hook cracks are one example of such features.
The latest development from NDT Global, Evo Eclipse, is the result of an extensive research and testing program. This development is designed to overcome limitations from current status quo ILI techniques and provide an alternative to accurately size tilted (i.e. hook cracks) and skewed (sloping) features.
In-line inspection of offshore pipelines using conventional tools and procedures is not always possible, due to a combination of various challenges. This paper discusses a recent example of such a case: the in-line inspection of an 8” fuel gas line feeding a platform located in the North Sea.
The pipeline was found to have a leaking Sub Sea Isolation Valve (SSIV). The SSIV is about 755 ft. (230 meters) away from the platform and riser. In addition, the topside Emergency Shut Down Valve (ESDV) had failed in the open position. Due to a combination of the ESDV being in an open position and the SSIV slowly leaking it was determined that the riser could not safely import the gas to power the platform. The SSIV was closed but since it was slowly leaking the riser was regularly bled to ambient pressure with the gas being sent to the flare.
In order to provide critical safety isolation of the fuel gas pipeline, the ESDV needed to be replaced. The integrity of the riser then needed to be confirmed by performing an in-line inspection. However, for the inspection to successfully take place, several challenges had to be overcome, including:
The ROSEN team, together with the operator, settled on a free-swimming, bi-directional, UT inspection solution. In order to provide a couplant for the UT, a liquid batch was proposed to be used. To overcome the fact that there was no flow possible, the team agreed to use external pumps to propel the bidi UT tool in a liquid batch into the riser, while, at the same time, compressing nitrogen against the SSIV. Once the tool had reached the desired location, the compressed nitrogen was used to push the pig train back to the launcher.
This paper will discuss why this solution was selected and how the collaboration between ROSEN and the operator successfully tackled the challenges to develop and apply the free-swimming UT-based solution and safely inspect the pipeline.
A combination of complex economic conditions and diminishing production in mature fields continues to drive growth in the oil and gas decommissioning market. Whilst industry attention tends to focus on well plug and abandonment or topside removal and dismantling, subsea infrastructure poses its own challenges. When a pipeline system reaches the end of its operational life multiple options may exist for cleaning and decommissioning. Pipeline configuration, condition, contents and available disposal routes will all have a bearing on the chosen methodology. A five-year decommissioning programme of over 1,800 km of multiple subsea infield and export flowlines of varying diameter, has offered a unique opportunity to utilise experiential learning to apply best practice to pipeline end of life.