Abstract
Europe’s largest gas field, the Groningen field (the Netherlands), is widely known for induced subsidence and seismicity caused by gas pressure depletion and associated compaction of the sandstone reservoir. Whether compaction is elastic or partly inelastic, as implied by recent experiments, is a key factor in forecasting system behavior and seismic hazard. We sought evidence for inelastic deformation through comparative microstructural analysis of unique drill core recovered from the seismogenic center of the field in 2015, 50 yr after gas production started, versus core recovered before production (1965). Quartz grain fracturing, crack healing, and stress-induced Dauphiné twinning are equally developed in the 2015 and 1965 cores, with the only measurable effect of gas production being enhanced microcracking of sparse K-feldspar grains in the 2015 core. Interpreting these grains as strain markers, we suggest that reservoir compaction involves elastic strain plus inelastic compression of weak clay films within grain contacts.
Original language | English |
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Pages (from-to) | 483-487 |
Number of pages | 5 |
Journal | Geology |
Volume | 49 |
Issue number | 5 |
DOIs | |
Publication status | Published - May 2021 |
Bibliographical note
Funding Information:We thank J. van Elk, D. Doornhof, C. Visser, D. Doran, F. Marcellis, T. Wolterbeek, R. Keijzer, E. Gutiérrez, S. Matveev, S. Waldmann, and L. Bik. D. Healy, R. Gaupp, and an anonymous reviewer provided helpful comments. The work was funded by Groningen field operator Nederlandse Aardolie Maatschappij BV (NAM) (agreement UI49358). European Research Council starting grant SEISMIC 335915 supported Hamers.
Publisher Copyright:
© 2020 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license.