Case Study - SBRC of a Geothermal Reservoir in Cooper Basin, Australia

When permeability of a geothermal reservoir is going to be improved, this is achieved by fluid injection and is resulting in pore pressure pertubations and causes microseismicity along pre-existing fractures since the effective normal stress changes. Triggering a microseismic event can be characterized as diffusional process of pore pressure relaxation. Examining the spatio-temporal dynamics of the induced microseismicity gives estimates of hydraulic properties of the reservoir. In this paper several Seismicity Based Reservoir Characterization (SBRC) techniques have been applied on a Cooper Basin data set to obtain values for hydraulic diffusivity and permeability. Every approach gives consistent order of magnitude results for the hydraulic properties. Estimations were made for an isotropic approximation as well as for an anisotropic estimation of the reservoirs hydraulic parameters. In addition a statistic based approach was applied obtaining a scalar value for diffusivity and permeability by using the occurrence probability of fluid-induced microearthquakes.