Geological stress state calibration and uncertainty analysis

Abstract

The stress state is an important controlling factor on the slip behavior of faults and fractures in the earth's crust and hence on the productivity of faulted and fractured hydrocarbon reservoirs. Uncertain or poorly constrained estimates of stress states can lead to high risk both in drilling and production costs. Current methods for stress tensor estimation rely on slip vector field data, however, this information is not generally available from datasets that are commonly used in the oil and gas industry. This work presents an approach whereby predicted slip tendency is used as a proxy for fault displacement, which can easily be extracted from datasets routinely used by the oil and gas industry. In doing so, a calibration approach is developed in order to estimate the parameters governing the underlying stress state by calibrating slip tendency predicted by the 3DStress® software to match measured slip displacement. A Bayesian approach is employed, and several uncertainty sources are accounted for in the estimation process, including the impacts of limited data and correlated data taken from geologically similar measurement locations. ©2010 Society for Experimental Mechanics Inc.