Thermo-poroelastic AVO modeling of Olkaria geothermal reservoirs

Seismic AVO has a significant potential for fluid identification in time-lapse monitoring of the cyclic recovery of geothermal reservoirs. With this goal, we develop an AVO method based on the reflection and transmission (R/T) of elastic waves at an interface between two fluid-saturated thermo-poroelastic media. The method is applied to the Olkaria geothermal reservoir modeling in Kenya. This system is characteristic of a natural cyclic recovery, where cyclic meteoric water undergoes complex phase transition and thermo-hydro-mechanical coupling process. Conceptual models are built based on petrophysical and thermophysical properties of trachyte thermal reservoirs, and the fluid properties under different temperature conditions have been considered. A plane-wave analysis illustrates the effects of thermal conductivity, specific heat, and porosity on velocity dispersion and attenuation of the fast-P, Biot P, and thermal P waves. AVO modeling by P-wave incidence is conducted to investigat...