A study of subsurface integrity issues for the Mondarra underground gas storage field
Jonathan Serfaty A , Mark Pogson B and Bashirul Haq CA UWA and APA Group
B APA Group
C UWA
The APPEA Journal 51(1) 215-224 https://doi.org/10.1071/AJ10015
Published: 2011
Abstract
In gas reservoirs, issues related to declining deliverability and injectivity, well integrity and reservoir integrity are often found. These may become more common, however, in fields used for underground gas storage (UGS). This may be due to extreme operating conditions–primarily cyclical phases of production and injection often associated with large pressure and temperature fluctuations within the reservoir and wellbore, in addition to operating with significant pressure depletion.
This study identifies specific sub-surface integrity issues that have affected the Mondarra gas storage facility. The Mondarra facility is Western Australia’s only UGS operation, owned and operated by the APA Group: Australia’s largest natural gas infrastructure business. Specific sub-surface integrity issues related to UGS were investigated. Results indicate that the production and injection cycles have decreased deliverability by 4.4% annually since 2007, primarily by plugging pore throats with inorganic precipitates, such as siderite and organic residues from the reciprocating compressor.
Reservoir integrity, represented as a reduction in effective connected volume, has been identified as an issue following early re-pressurisation of the field. Detailed production monitoring and reservoir modelling has been used to investigate this risk and determine the likely range of outcomes. The mechanism of this reduced effective connected volume is uncertain; however, suggested reasons include: pressure-induced changes in the conductivity of micro-fractures and transmissibility of faults; compaction of the reservoir; or, water encroachment post depletion. Furthermore, sub-surface modelling has indicated a complex connectivity picture with multiple compartments and variable permeability layers impacting gas storage operations.
Jonathan (Jon) Serfaty is an Honours student from the University of Western Australia. Half-way through 2011, he will graduate from a Bachelor of mechanical engineering (petroleum engineering), and a bachelor of commerce–with a major in management and human resources management. Jon has worked with APA Group since 2007 as an undergraduate mechanical engineer and more recently from 2009, as an undergraduate petroleum engineer on the Mondarra underground gas storage reservoir. Member: SPE, Engineers Australia. Jon.Serfaty@apa.com.au |
Mark Pogson is a petroleum engineer with more than 20 years industry experience in both research and working for operating companies, including BG Group, Mobil and Woodside. He has a wide range of expertise in reservoir and production engineering with an emphasis on field appraisal and development. He is an independent consultant working for the APA group as their Mondarra sub-surface engineering manager. Mark has a BSc (Hons) in chemistry/geochemistry and a PhD in chemistry from Leicester Univeristy (UK), and an MSc (DIC) in petroleum engineering from Imperial College London. Mark has been a Society of Petroleum Engineers member for over 20 years and served as a SPE WA section committee member in 1997 and 2000. He was also the chairman and editorial committee member of SPE News Australasian Newsletter and Journal from 1996 to 2001. Mark.Pogson@apa.com.au |
Bashirul Haq is a part-time lecturer and PhD scholar at UWA. Mr Haq was associate lecturer at the School of Oil and Gas Engineering, and then the School of Mechanical and Chemical Engineering at UWA from 2006–2008. Previously, he worked for the Department of Petroleum and Mineral Resources Engineering (PMRE) at BUET Bangladesh from 2001–2006. He received a master of science in petroleum engineering and a bachelor of science in chemical engineering from Bangladesh University of Engineering and Technology (BUET). He was the treasure of SPE Bangladesh Section in 2006. bhaq@mech.uwa.edu.au |
