A GEOMECHANICALLY-BASED INVERSE METHOD FOR INTERPOLATING THE THREE-DIMENSIONAL STRESS FIELD IN A FAULTED RESERVOIR

Information concerning the nature of the stress field in a reservoir is necessary for many oilfield applications, such as pre-drill wellpath planning and fault seal analysis. Available data usually include stress orientation and magnitude estimates of various quality along a limited number of wellbores. Current methods to map the reservoir volume stress field from these point and/or line data range from simplistic averaging to more sophisticated interpolation and geostatistical techniques. We present a new method to interpolate stress throughout a reservoir volume using a geomechanically-based numerical boundary element code, Poly3D, coupled with a weighted damped least-squares inverse solver. The primary advantage of this methodology over others is that the stress solution includes the effect of elastic interactions among faults. The code uses as input a 3D fault framework, with or without mapped displacements, and estimates of stress orientation and magnitude from wellbores, which can be weighted to data quality. Output is in the form of a ‘best-fit' remote stress field, which is in turn used to forward model the volumetric stress field. Results illustrating the utility of our tool are presented for a number of faulted reservoir scenarios.