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Intelligent integrity

Oilfield Technology,

Sara Ortwein and Carol Lloyd, Upstream Research Company, emphasise the importance of maintaining operational integrity.

Ensuring operational integrity is critical to the safe, environmentally responsible, and economic development of hydrocarbon resources everywhere in the world. In a business that is capital intensive and complex, integrity management is critical and is the foundation of design choices and operating practices throughout the industry. At ExxonMobil, integrity management is also a core research area.

ExxonMobil’s Upstream Research Company (URC) performs research in the areas of wellbore, marine and facility integrity. Its research efforts cover aspects of integrity management over the whole life cycle of assets: design, prevention and mitigation, and early detection.

Design integrity

Integrity starts with a robust design, which considers the service and the operating environment, over the expected life of the asset. Well integrity is supported with a full-scale tubular goods test facility that provides well integrity solutions to drilling engineers around the world. This facility assists with selecting and testing the appropriate pipe and connections to ensure well integrity over the life of the wells through comprehensive full-scale test evaluations of pipe and premium threaded connection options.

The company has developed a connection testing protocol that has been recognised by the industry. The full-scale testing evaluation provides high confidence in design integrity of the tubular connection as the evaluation protocol goes beyond ISO and API standards. The company is also actively involved in API 5C5 code development and enhancing industry standards for connections evaluation testing. The drilling research team has developed full-scale, cold temperature (-20°F and lower) make-and-break test capability that simulates rig floor conditions in extreme cold weather climates and represents a step change in tubular technology. This capability enables the lab to assess the impact of sub-freezing temperatures on premium connection make-up and seal performance, ultimately providing quality assurance and verification of performance before the pipe is installed in the well.

The company also has extensive research programmes in marine and subsea integrity, which cover the infrastructure and facilities required for offshore production and processing, such as offshore platforms (fixed or floating), mooring and riser systems and subsea production facilities. The company’s experience in hydrodynamics lays a solid foundation for technology development in floating structure design and operations. For example, the company has developed methodologies and technologies to discern and verify wave impact loads for platform design and construction. Another element of this line of research involves wave basin model testing. In addition to carrying out individual model tests for measuring loads and responses, our expertise includes developing methodologies for conducting a large number of model tests to characterise the variability in magnitude of loads on structures due to extreme anticipated conditions. Statistical evaluation of this suite of tests is then used to develop robust design criteria for offshore structures. Through this work, URC has extended learnings from wave impact model testing for our platforms and has made improvements to sensor qualification procedures to further reduce experimental uncertainties in future wave impact model tests.

Another area of focus is pipelines. With pipelines as the major means of oil and gas transportation, pipeline integrity research is critical for ensuring pipeline safety and security. The company’s materials lab has succeeded in characterising material microstructure and mechanical properties necessary for investigating pipeline performance. The lab also provides us the capabilities of designing and conducting novel materials assessment protocols. The company has spent more than 10 years in developing an industry-leading pipeline strain-based design (SBD) technology. SBD assists in designing and building pipelines in harsh environments where ice gouging, permafrost changes and seismic activities cause significant pipeline deformation. Since there is no industry standard on SBD, the EMpipeTM technology assists our affiliates in designing, building and operating pipelines in such environments. The technology has been applied to the company’s Sakhalin and Papua New Guinea pipelines. With the technology commercialised, URC has positively influenced the industry and pipeline regulators regarding this engineering challenge.

Prevention and mitigation

In the area of drilling and well integrity, URC researchers use finite element analysis (FEA) for connection assessment and well integrity. The FEA capability enables researchers to undertake well-specific analyses. Recently, approximately 160 brownfield platform wells in the Middle East were assessed as to whether they were fit-for-service by using thermo-mechanical modelling and finite element analysis technologies to confirm structural integrity of shut-in wells. The assessment helped define a cement remediation programme.

In the area of marine integrity, the environment can have a large impact on offshore platforms. This led to the development of an FEA-based methodology for assessing the fitness-for-service of mooring chains with material loss due to corrosion and wear. The results, in conjunction with mooring loads calculated from mooring analyses, can help better define the capacities of various mooring systems. In addition, with an engineering-based projection of degradation rate and acceptable operation risks, the residual strength calculations can be used to assess the remaining life and provide guidance to the timing of mooring system replacement while ensuring operation integrity.

In the area of pipeline integrity, management of potential corrosion and flow assurance issues is a key focus. This research mitigates these issues through optimal materials design, robust chemical treatment programmes, and comprehensive maintenance and inspection practices. The reliable prediction of produced fluid properties, multiphase flow dynamics and impacts of solids formation in oil and gas production systems is crucial for both defining robust flow assurance management strategies and also accurate prediction of corrosion-mediated processes.

The company’s flow assurance laboratories provide industry leading research in the areas of fluid analysis, hydrates, waxes, emulsions, and other solids typically encountered in producing wells/flowlines. Capabilities at the lab include multiphase flow loops simulating field conditions, advanced fluid property testing methodologies and interfacial phenomena characterisation. Fundamental research in these areas has driven the development of flow assurance predictive models for estimating liquid droplet entrainment that allow for cost-effective corrosion prevention and management strategies.

The company’s corrosion research is enabled through its materials and corrosion laboratory, which houses industry leading capabilities that allow for safely performing experiments under typical, field operating conditions. In one recent example in an oil producing field experiencing high corrosion rates due to CO2 and microbial influenced corrosion interactions, predictive multiphase flow modelling was used to identify flow regime changes in the pipeline possibly responsible for higher corrosion rates in specific sections of the pipeline. This analysis was confirmed by pipeline inspection data. Inhibitor qualification tests under higher shear conditions allowed for effective modifications to the corrosion inhibitor management strategy to mitigate these enhanced localised corrosion processes.

Early detection

No matter how well facilities are designed and operated, there is always the potential for integrity issues due to prolonged exposure to produced fluids and the environment. For this reason, research also includes developing more sensitive and safe leak detection. Two examples are pipeline leak detection and detecting fugitive emissions at our processing facilities.

In the area of pipeline integrity monitoring, the company aims at developing and applying more reliable and robust leak detection systems than the conventional technologies. One example is our work with an industry team to develop a fibre-optic system that significantly improves detection sensitivity and accuracy. In field tests, we have seen at least two orders of magnitude improvement in leak size detection and several orders improvement in leak location detection. While this tool is not yet commercially proven, it shows great promise.

Another key safeguard of facilities integrity is early detection of hydrocarbon leaks. For decades, wired flammable gas detectors have been the industry standard. However, due to the infrastructure requirements such as wiring and conduits, the wired solution is costly and labour intensive. ExxonMobil successfully adopted and tested wireless gas detectors. These new wireless gas detectors use micro electro-mechanical system technology to reduce power consumption and thus extend battery life. In addition, unlike many wired gas detectors, they do not require calibration throughout the entire field life.

ExxonMobil Research Qatar and Providence Photonics have partnered since 2009 to develop the IntelliRedTM Remote Gas Detection system that integrates computer vision algorithms and infrared technology to autonomously scan for and identify small leaks. Efficient identification of these emission sources can lead to better control and maintenance activities. The technology was commercialised in 2014 and has since been deployed at six process facilities worldwide.These are just a few examples of integrity management that are being actively worked on a daily basis by the company’s global upstream research organisation. Company facilities are designed and built with integrity in mind and monitored to ensure integrity over the life of the facility. Delivering the world’s energy needs is a tough challenge. That is why ExxonMobil take integrity management seriously and consider it a fundamental part of doing business.

Edited from an article by Sara Ortwein and Carol Lloyd.

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