An analytical method for determining horizontal stress bounds from wellbore data

Abstract

Several issues including control of stress-induced wellbore instability and design of deviated and horizontal wellbores require knowledge of the magnitude and orientation of the in-situ stress field. An analytical method has been developed to determine bounds to the in-situ horizontal stresses from wellbore data for cases where the explicit measurement of stresses is not available. The method has been used to determine the anisotropic stress state at depths between 1000 m and 4000 m in the immediate region of the Cossack and Wanaea fields in the North West Shelf of Australia. The validity of the method is demonstrated by the satisfactory comparison of the determined stress bounds with the minor and major horizontal stresses estimated directly from modified leak-off tests.