Work package 1 | Impact of depletion and re-inflation on reservoir and caprock behaviour

Summary

This work package is focussed on providing a better understanding of the impact of depletion and re-inflation on reservoir and caprock material. During this process the sandstone reservoir will deflate and re-inflate, much like a balloon. This kind of process can alter the physical properties of the rocks and potentially cause movement on faults and/or damage to infrastructure. As part of CONTAIN, BGS will carry out unique experiments examining the way in which different rocks within storage sites may respond in different deflation and re-inflation scenarios. This will provide valuable datasets, which can be used by modellers and will feed directly into work package 2. The results will also add to our general understanding of these processes and the likely behaviour of such materials.

Technical information

This work package seeks to understand the roles of the stress tensor, the stress path and associated mechanical deformation in determining permeability changes affecting both the sealing efficiency of indurated hydrocarbon caprocks and HM response of reservoir materials during reservoir depletion and re-inflation. Critical state mechanics shows that complex deformation can be described by a series of yield surfaces in the p′–q′–ν parametric space. Generalised statements regarding the evolution of permeability can be imposed on this framework, but little work has been done to quantitatively map these changes in detail. Calibration of the model occurs by taking samples of reservoir and caprock material along compressional and extensional stress paths extending to the yield surface while measuring the resulting permeability changes. BGS will do this by performing a series of tests in one of their bespoke triaxial systems, simulating the change in pressure during production and the resulting re-inflation from CO₂ injection.