Abstract

Abstract

Application of Rock Physics Study to Seismic Monitoring of Injected CO2 in Geological Sequestration
Journal of geography, 114, 6, 988-1002, 2005.
Xue Ziqiu

The ultimate goal of rock physics is to gain insights into the physical properties of a reservoir. A rock physics study makes use of measured elastic properties from seismic data to generate attributes that yield information about reservoir rocks. For example, if we measure the velocity of a seismic wave propagating through an aquifer or an oil reservoir, rock physics provides the theory to convert the measured physical value into information about the fluids present in the rock. This paper describes an application of rock physics study to the seismic monitoring of injected CO2 in geological sequestration.@Laboratory experiments on porous sandstones show that the P-wave velocity reduction due to injected CO2 is typically on the order of |10%. The results of the seismic tomography show that the CO2 migration pattern is consistent with the pore space distribution within porous sandstone. Such results support the applicability of a seismic survey to CO2 monitoring in geological sequestration. Measurements on a core recovered from the Nagaoka pilot site show that the P-wave velocity reduction agreed well with sonic logging results. History matching with velocity changes of a sonic P-wave caused by a CO2 breakthrough at observation well OB-2, was successfully done based on Gassmann theory and the rock physics model in this study.