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Providing quick response time and accurate detection of small leaks in multiphase pipelines is of great importance for risk mitigation in the oil and gas industry. The emphasis of implementing state-of-the-art technologies to mitigate both safety and environmental risks in the field becomes of particular importance as aging pipelines transport sour hydrocarbon products crossing populated areas. Fiber Optics Leak Detection Systems (FOLDS) have the capability to detect small pinhole leaks even in multiphase flow, due to its distributed sensing and advanced signal processing features. With this motivation in mind, it is important to evaluate the ability of FOLDS to detect leaks under different scenarios of varying fiber cable location, product phase distribution, propagation media, pressure, temperature, leak sizes and leak locations.
Due to the high amount of varying parameters, safety hazards and environmental constraints associated with field testing FOLDS, an industrial third-party multiphase flow facility enables FOLDS performance evaluation across the range of applications of interest. In this particular case, different Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS) FOLDS were simultaneously tested for detecting the pipeline leaks. The overall performance test scope and procedure presented in this paper was custom developed to simulate as close as field parameters for validation across multiphase and wet gas flow conditions.
The customized performance evaluation test program led to results that show the sensitivity of technology performance to different operational conditions, ranging from physical flow parameters to fiber optic location with respect and leak propagation media. FOLDS solutions performance validation is presented in terms of leak detection, stability and consistency. This leads to a conclusive benchmarking of each solution performance based on the test results for multiphase pipelines.
This paper guides the audience through the methodology of customized performance evaluation testing of pinhole leak detection for oil multiphase and wet gas pipelines. It also provides value by highlighting the impact of testing procedures, different flow parameters and installation setups on the actual system performance.
Fagbami, Debo (Xenergi Oilfield Services) | Echem, Chukwudi (Xenergi Oilfield Services) | Okoli, Amaechi (Xenergi Oilfield Services) | Mondanos, Michael (Silixa Limited) | Bain, Andy (Silixa Limited) | Carbonneau, Patrice (Silixa Limited) | Martey, Amarquaye (Midwestern Oil)
Nigeria is Africa's biggest crude producer but its revenue is severely reduced by theft and attacks on oil pipelines that significantly impacts crude production and fuel supply. Substantial efforts have taken place in collaboration with local communities, producers and oil operators to engage New Technologies in a bid to combat oil theft and pipeline sabotage.
Integrity monitoring of oil and gas pipeline pipelines can quickly identify a leak or third-party incursion event. Distributed optical fibre sensing offers a pipeline monitoring system that is not available with any other technology. Early detection of a leak or intrusion together with the accurate identification of the location allows time for either safe shutdown or rapid dispatch of security, assessment and clean-up personnel giving benefits in terms of reduced environmental impact and reduced helth risks to the local population. An effective and appropriately implemented monitoring system can easily pay for itself through reduced product loss, potential consequential losses and an increase in public confidence.
A Distributed surveillance system one of the first installed in Nigeria will be introduced. The System has been introduced to the Umugini pipeline, a crude oil evacuation route for four Nigerian marginal field producers in the western Niger Delta. The system uses the FALCON Platform developed by Xenergi. The system includes intrusion detection and leak detection based on both acoustic and temperature variations. At the heart of the system are both the Ultima™ Distributed Temperature Sensor (DTS) and Distributed Acoustic Sensor (intelligent DAS) allowing coverage of ranges up to 10's km continuously.
The project had to overcome a number of challenges, including the variable installation conditions imposed by the terrain & local climate, contractors unfamiliar with the technology and community concerns. Overcoming these issues gave a system that delivers 24/7 coverage of the Umigini pipeline from a single monitoring location giving the operator financial benefits in reduced product loss and more efficient deployment of resources.
The Silixa intelligent Pipeline Surveillance System (iPSS™) allows oil & gas pipeline operators to continuously and simultaneously monitor for leaks and threats to the pipeline along its entire length, and is the only system that can offer such complete coverage. Utilising fibre optics and underpinning the detection technology is Silixa's world leading Ultima &
“Third Party Interference”, whether intentional or accidental, is responsible for more than half of the pipeline failures in the world. The consequences can be catastrophic for people, the environment but also for facilities availability. The project presented here considers the use of a communication optical cable, laid with the pipeline, in order to detect intrusions and also leaks. Field data from an operational test was acquired at the Balhaf LNG facility in Yemen in December 2012.
The LNG plant operations had been subject to numerous sabotage actions, impacting the pipeline feeding gas to the plant, and therefore the plant availability. A security review concluded that there was a need to implement specific security measures to allow early detection of potential threats. The requirement was to minimize new equipment installation in the field, so as to avoid personnel exposure, by making use of the already installed communication optic fiber communication cable.
A fiber optic based detection system was selected. Such systems detect acoustic signals via the optical pulses sent within an optical fiber, known as Rayleigh scattering. For example repeated and regular impacts on soil will trigger an “excavation” alert and a security team can be sent to stop intruders before they reach the pipeline. The advantage of this technology is that it makes use of one of the optical fibers within the communication cable, already installed in the pipeline trench. There is no need to install additional new cables alongside the pipeline.
Since its resulting installation, the system has demonstrated that this technology can reliably contribute to pipeline security by enabling operators to detect and listen to pipeline external threats. Fiber optics can also be used for leak detection. Such detection is based on the continuous measurement of the temperature gradient between the fluid transported and the surrounding ground, the environmental effects on the ground of the escaping product or the multiple acoustic signatures of a leak. This functionality is being tested and evaluated. This technology has the potential to drastically improve operational safety and security for pipelines deployed within challenging environments.
Unbonded flexible risers are a critical part of offshore field architecture bringing oil and gas from seabed to platforms on the surface. A failure in operation will result in stop of production and hence a significant loss of revenue. Risers are subject to a number of loading issues including internal and external pressure, vessel motions and current and wave actions. As a result, risers, endure significant strain levels which can impact on their integrity and functionality.
The recent implementation of fiber optic monitoring embedded in flexible risers, is an important step towards turning risers into inspectable structures. The embedded monitoring systems ensure the asset can operate safely at its optimum level for the maximum period of time. The combined use of optical point sensors and fully distributed sensors allow various events to be monitored. This includes breach of outer sheath, condensate build up, polymer temperature, pipe temperature during shut in, fatigue and wire break.
The traditional industry method for combating these issues has been extensive onshore testing on small sections of the riser allowing the operator to build up a bank of fatigue and reliability data which is used to statistically forecast the strains and stresses the riser will encounter. This data takes into account expected changes throughout the lifecycle of the riser, such as material degradation and environmental issues including storms and hurricanes. The main inspection method in operation to back this up has been expensive inspection campaigns by diver or ROV focusing on external damage.
New advances in optical technology and riser manufacturing techniques mean that a suite of real-time monitoring can provide a far more accurate picture of a riser's condition during operation. This improves decision making by allowing structural and temperature issues to be detected at the earliest possible stage and rectified in the most efficient manner, ensuring risers satisfy safety and regulatory requirements and help maximize oilfield productivity. The enabled condition dependent maintenance of risers will reduce the need for expensive ROV operations for inspection.
Real time riser monitoring is set to play an increasingly important role as the operators start to insist on the adoption of this technology in the risers delivered to them. As oil production reaches into deeper and deeper water depths, the real time understanding of the integrity of the risers will become paramount.
This paper details the advances that have been made in optical monitoring and visualization techniques and their application within the intelligent riser.