Proxies for Quantifying Depletion-Induced Reservoir Compaction in the Groningen Field

Reservoir compaction caused by pressure depletion in gas reservoirs is considered an operational risk as it may induce surface subsidence. As a result of decades-long production, the Groningen Field (NLD) is experiencing such problems, in combination with induced seismicity. In this contribution, we report a large number of uniaxial-strain pore pressure depletion experiments that were performed using fresh core material obtained from the center of the subsidence bowl in the field. We investigate what factors control the elastic and inelastic deformation. Focusing specifically on the cracking mechanisms operative in the sandstone material, we utilize statistical modeling techniques to identify three independent proxies that explain the inelastic deformation measured. The proxies, namely porosity, skewness of the particle size distribution, and ‘weak’ mineral content, are consistent with an early stage of a progressively failing grain aggregate. Our results not only help to understand the cracking mechanisms in the sandstone, but also suggest an important role of the depositional environment. The latter motivates a reexamination of compaction behavior at larger scale, and its association with basin evolution at geological timescales.