Title
Geomechanics response and induced seismicity during gas field depletion in the Netherlands
Author
van Wees, J.D.A.M.
Buijze, L.
van Thienen-Visser, K.
Nepveu, M.
Wassing, B.B.T.
Orlic, B.
Fokker, P.A.
Publication year
2014
Abstract
In this paper we present a review ofcontrolling geological, tectonic and engineering factors lor induced seismic¡ty associated to gas depletion in the Netherlands and we place experiences from extensive Dutch geomechanical studies in the past decade in the contex[ ofgeneric models for induced seismicity. Netherlands is in a mature gas production phase, marked by excellent subsurface structural and stratigraphic characterization. Over 190 gas fields ofvarying size have been exploited. No more than 15% of these nelds show seismicity. Ceomechanical studies show that, similar to the EGS stimulation phase, largest seismicity is localized on pre-existing ¡ault structures. However, the prime cause for se¡smicity in gas depletion is differential compaction, whereas in EGS stimulation related pressure build-up and fluid pressure diffusion along the faults form the prime mechanism. On the other hand, our study has a close theoretical analogy to resewoirs where the fluid volumes extracted are significantly larger than the re-injected volumes, and which can result in (differential) reservoir compaction. The observed onset ofinduced seismicity in the Netherlands occurs a¡tera considerable pressure drop in the gas fields. Geomechanical models show that both the delay in the onset of induced seismicity as well as the non-linear increase in seismic moment observed in the induced seismic¡ty, can be explained using a model of differential compaction, if the faults involved in induced seismicity are not critically stressed at the onset oldepletion. The presented model serves to highlight key aspects ofthe interaction of init¡al stress and differential compaction in the framework of induced seismicity in Dutch gas Relds. It is not intended as predictive model for induced seismicity in a particular field. To this end, a much more detailed field specific study, taking ¡nto account the full complexity of reservoir geometry, depletion history, mechanical properties and initial stress field conditions is required.
Subject
Earth / Environmental
SGE - Sustainable Geo Energy AGEA - Advisory Group for Economic Affairs PG - Petroleum Geosciences
ELSS - Earth, Life and Social Sciences
Geological Survey Netherlands
Geosciences
Energy / Geological Survey Netherlands
Induced seismicity
Gas depletion
Geomechanics
Tectonics
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http://resolver.tudelft.nl/uuid:c62b6306-eaca-43f3-b17e-1b216d07e594
TNO identifier
513108
Source
Geothermics, 52, 206-219
Document type
article