Measurement of gas contents in shale reservoirs – impact of gas density and implications for gas resource estimates
Jamiu M. Ekundayo A B C , Reza Rezaee A and Chunyan Fan AA Western Australian School of Mines: Minerals, Energy and Chemical Engineering, Curtin University, Perth, WA 6102, Australia.
B State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China.
C Corresponding author. Email: jamiu.ekundayo@postgrad.curtin.edu.au
The APPEA Journal 61(2) 606-610 https://doi.org/10.1071/AJ20177
Accepted: 15 March 2021 Published: 2 July 2021
Abstract
Gas shale reservoirs pose unique measurement challenges due to their ultra-low petrophysical properties and complicated pore structures. A small variation in an experimental parameter, under high-pressure conditions, may result in huge discrepancies in gas contents and the resource estimates derived from such data. This study illustrates the impact of the equation of state on the gas content determined for a shale sample. The gas content was determined from laboratory-measured high-pressure methane adsorption isotherms and theoretically described by a hybrid type model. The modelling involved the use of the Dubinin–Radushkevich isotherm to obtain the adsorbed phase density followed by the Langmuir isotherm to describe the resultant absolute adsorptions. Significant variations were observed in measured adsorption isotherms due to the variations in gas densities calculated from different equations of states. The model parameters and the gas in-place volumes estimated from those parameters also varied significantly.
Keywords: high-pressure volumetric analysis, adsorption isotherms, gas contents, gas shale reservoirs, Dubinin–Radushkevich (DR) isotherm, Langmuir isotherm.
Jamiu Ekundayo is a PhD student in the Discipline of Petroleum Engineering, Western Australian School of Mines (WASM): Minerals, Energy and Chemical Engineering at Curtin University. His PhD is focused on shale gas sorption hysteresis and how it affects gas production from shale gas reservoirs. He holds a MSc degree in Petroleum Engineering from the Petroleum Institute (now part of Khalifa University), Abu Dhabi, UAE and a BSc (hons) degree in Petroleum & Gas Engineering from University of Lagos, Nigeria. He has over 10 years of reservoir engineering, teaching and research, and data science experience. |
Professor Reza Rezaee of Curtin University has a PhD in Reservoir Characterization. His research has been mostly on integrated solutions for reservoir characterisation, formation evaluation and petrophysics. He has also worked on the application of artificial intelligence in the oil and gas industry for many years. Currently, he is focused on unconventional gas including shale gas and tight gas sand studies. He has over 27 years of experience in academia and has published more than 170 peer-reviewed journals and conference papers and is the author of five books. As a founder of the ‘Unconventional Gas Research Group’ of Australia, he has established a unique and highly sophisticated research lab at the Department of Petroleum Engineering, Curtin University. This lab was established to research petrophysical evaluation of tight gas sands and shale gas formations. He is the Editor-in-Chief of Improved Oil and Gas Recovery journal, Associate Editor of Marine and Petroleum Geology and Associate Editor of Geofluids. |
Dr Chunyan Fan received her BEng from China University of Petroleum (East China) and doctoral degree from the University of Queensland. She is currently a Senior Lecturer in Chemical Engineering, Curtin University. Her research is mainly focused on the fundamental mechanisms of various adsorption phenomena in physical science and engineering and is a member of the International Adsorption Society. She has published more than 40 articles in international well reputed journals in this discipline and is the recipient of DECRA (2016). |
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