Inversion technique to determine the in-situ stress field from fracturing data

Abstract Typically one assumes that the two horizontal in-situ stress are equal in borehole stability studies. This simplification has been necessary due to the lack of information. The new method presented here distinguishes between the in-situ stresses and estimates the magnitude and the direction of each of the two horizontal in-situ stresses. The input data used are the leak-off fracturing information. The new method uses stress transformation equations to take advantage of the directional characteristics of off-shore boreholes. By including the hole inclination and the azimuth, one can solve the two unequal horizontal in-situ stresses. The model results in finding the inverse of an overdetermined system of equations. A field study demonstrates the method.