Characteristics of SH-wave propagation during oil reservoir excitation using BEM formulation in half-plane model representation

The application of elastic waves induced through seismic excitation (stimulation) to increase the oil recovery from a hydrocarbon reservoir as an enhanced oil recovery (EOR) technique is currently in its infancy. Seismic stimulation is a cost-effective and efficient method for enhancing oil production from waterflood reservoirs by increasing areal sweep performance and decreasing water cuts, hence extending the productive life of a mature oilfield. It has great prospect in offshore fields where technological difficulties and restrictions hinder the deployment of other EOR methods. Herein, this study investigates the effects of a direct impact of seismic SH-wave on a 2D transient behaviors of an oil reservoir with a half-plane model. In the time domain, a half-plane model containing a poroelastic oil reservoir is formulated using a boundary element method (BEM). The model considers complete seismic SH-wave propagation using Ricker wavelet, from a down-hole source via a partially saturated oil reservoir to ground surface receiving points. The model is based on 2D elastodynamic and Biot's dynamic poroelasticity equations. A DASBEM program is incorporated into MATLAB (2022a) to develop a model of wave propagation. The result showed that variable incidence angle affects the frequency and time domain responses, while the depth of the reservoir and porosity influence the amplitude of oscillation. Synthetic seismograms at stations above the oil reservoir indicated attenuation and numerous diffracted waves with various time delays. Multiple SH-wave reflections in the reservoir amplify 3D signals, while at higher dimensionless frequencies, effect of porosity amplify the distant locations. This technique can be utilized as fluid indicator to monitor wave based EOR using SH-wave attenuation, and to detect and visualize the permeability changes in reservoir (impermeable boundaries) during CO2 plume storage for the purpose of monitoring the safety of CO2 geo-sequestration. © 2022