Effects of rapid gas decompression on coal seam gas swellables
Matthew B. Thompson A * , Jan Bon B , Mike Vatan A and Mohammad Zaman AA Santos Ltd, 32 Turbot Street, Brisbane, Qld 4000, Australia.
B Petrolab Australia Pty Ltd, 45 Woodforde Road, Magill, SA 5072, Australia.
The APPEA Journal 62 S187-S191 https://doi.org/10.1071/AJ21166
Accepted: 7 March 2022 Published: 13 May 2022
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of APPEA.
Abstract
Thousands of non-stimulated coal seam gas (CSG) wells in Queensland’s Surat Basin rely on swellable packers as the first line of defence against interburden solids production and poor well run life. This paper is aimed at understanding some of the impacts of long-term well operations on swellable performance from rapid changes in downhole pressure. For the first time, rapid gas decompression (RGD) effects on CSG swellables were experimented on in a quantitative manner as an analogue to underbalanced workover and pump trip conditions. RGD has the potential to break down swellables due to rapid release of high-pressure methane diffused in the rubber matrix resulting in a flow path for interburden solids. Five commonly available swellables from the CSG market were lab-tested for rapid decompression with methane at operational conditions. Coupon samples were swollen to representative conditions and placed in an autoclave under high-pressure methane, then rapidly decompressed in cycles. Results of this study showed relatively low levels of physical degradation under test conditions but shrinkage effects varied between products largely grouped into material properties, confirmed with separate ambient shrinkage test. As such, the focus on swellable placement geometry remains paramount.
Keywords: borehole geometry, CSG, decompression, de-swell, interburden, isolation, rapid gas decompression, RGD, shrinkage, swellable, swellable packer, underbalanced workover.
Matthew B. Thompson has been working as a Drilling and Completions Engineer in the Queensland CSG industry since 2012. His current role is a Drilling Engineer for Santos’s GLNG project responsible for managing rig operations with Ensign and Savanna drill rigs throughout Fairview, Roma and Scotia CSG fields. Responsible for spearheading a number of operational and design improvement projects aimed at reducing well construction costs, testing new technologies trials, fluid and cuttings management and process safety initiatives. Other key responsibilities include front-end well design, contract management, Wellview and regulatory reporting. Matthew has played a key role in deployment and testing of swellable packers throughout the Surat Basin since 2013. He graduated from The University of Adelaide in 2012 with a Master of Petroleum Engineering. Prior to this, he practiced as a professional Civil and Environmental Engineer focusing on municipal water treatment and network operations, design and project management projects for United Water’s Adelaide, Ballarat and New Zealand contracts. He is a chartered professional member of Engineers Australia, a registered professional engineer of Queensland, and a member of SPE. |
Jan Bon obtained his Bachelor of Engineering in Petroleum Engineering from the University of New South Wales and his PhD from the Australian School of Petroleum, the University of Adelaide. He is a committee member of SPE South Australia. During his time in academia, his research work related to miscible phase behaviour of reservoir fluids with CO2 relating to the injection of CO2 for sequestration and enhanced oil recovery. He has previously worked as a Senior Reservoir Engineer at Santos Limited working on development of volatile oil and gas condensate reservoirs of the Cooper Basin and screening of oil reservoirs for carbon capture and storage. Since 2013 he is the Manager of Petrolab Australia, specialising in the sampling and PVT analysis of reservoir fluids, including phase behaviour, flow assurance and miscibility studies at reservoir conditions. |
Mike Vatan is an energy sector drilling and completion professional with over 22 years of experience across four different countries and six major operators. He has worked in different capacities both in the field and in the office to deliver drilling campaigns and supervise drilling and well intervention engineering activities. For those who know Mike, his main passion is to innovate and deliver the next new technical breakthrough solution which will take the industry to the next level of performance. Mike is currently working for Santos where he has worked as Staff Completion Engineer and Senior Petroleum Engineer for the past 7 years. Mike has a Bachelors in Petroleum Engineering and Masters in Reservoir Engineering. He is a member of Engineers Australia, registered professional engineer of Queensland, and a member of SPE. |
Mohammad Zaman has a Bachelors’ degree in Chemical Engineering and is the Drilling Team Leader in the CSG Drilling and Completions department at Santos Ltd. He has over 12 years experience in Drilling and Completions across Queensland CSG and Vietnam offshore. Mohammad leads a team of engineers delivering the planning and execution of CSG well construction. He is a chartered professional member of Engineers Australia, a registered professional engineer of Queensland, and a member of SPE. |
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