Multiplet Analysis for Estimation of Critical Pore-Pressure of Fractures Inside Geothermal Reservoirs

Abstract

Microseismic multiplets are introduced to estimate the critical pore-pressure of fractures required for shear slip during hydraulic fracturing of a geothermal reservoir. Because the multiplets can be used to estimate the precise source locations using cross-spectrum analysis, the orientations of hydraulically activated fractures are derived from the source locations of multiplets. The critical pore-pressure required for shear slip of fractures is estimated using the fracture orientations and the stress field that was measured in a borehole. The method and the results of its application to microseismic multiplets at Soultz field, France, are demonstrated. The feasibility of the method for estimation of pressure distribution and fluid flow in a reservoir is also discussed.