A feasibility study of CO2 sequestration monitoring using the mCSEM method at a deep brine aquifer in a shallow sea

Abstract

Reservoir production monitoring using mCSEM has been studied because it is sensitive to resistivity changes resulting from variations in hydrocarbon saturation. However, mCSEM for CO2 sequestration monitoring has scarcely been investigated, although the mCSEM method is advantageous for monitoring CO2 injection and migration because of high correlation between CO2 saturation and resistivity. In order to investigate the feasibility of mCSEM monitoring for CO2 sequestration, we conducted numerical experiments of representative CO2 injection models at a deep brine aquifer in a shallow sea. By using a modified secondary field method, we effectively addressed airwave problem occurring when mCSEM is applied to a target beneath a shallow sea. Furthermore, the developed 2.5D modeling algorithm was satisfied with very high accuracy which is essential for the simulation of electromagnetic fields generated by CO2 injection in a deep brine aquifer. The mCSEM response of CO2 sequestration reservoir, which is enhanced by modified secondary field method, is small but measurable changes in a given pseudo-realistic CO2 sequestration scenario.