Induced-seismicity geomechanics for controlled CO2 storage in the North Sea (IGCCS)

Abstract

In this study (IGCCS), we evaluate the feasibility of micro-seismic (MS) monitoring of CO2 injection into storage candidates in the North Sea to ensure safe operations. MS monitoring relies on measuring seismic signals resulting from abrupt subsurface movements such as the (re)-activation of faults and fractures. To be successful, MS monitoring technique requires a broad quantitative characterization of the subsurface behavior concerning its geology, geomechanics, and seismicity. Hence, we performed advanced triaxial tests combining with acoustic emission (AE) acquisition, followed by advanced coupled flow-geomechanics simulations to understand micro-seismicity more quantitatively. The test results are then scaled up and applied to a synthetic field-scale seismic data study. We tested shale, mudstone, and sandstone cores under confining and pore fluid pressure, with loading conditions that are representative of potential CO2 storage sites in the North Sea. Our work focuses on quantifying the effects of injected fluid type and temperature on mechanical behaviour and associated MS response of subsurface sediments. The current manuscript covers only the main findings and insights obtained during IGCCS, and for more details, refers to relevant publications resulting from IGCCS.

Keywords: CO2 injection, micro-seismic, acoustic emission, geomechanical behaviour, CCS, North Sea, multiphysics modelling, fluid type, temperature