INVERSION TECHNIQUE TO DETERMINE THE IN-SITU STRESS FIELD FROM FRACTURING DATA

Aadnoy, B.S., 1990. Inversion technique to determine the in-situ stress field from fracturing data. J. Pet. Sci. Eng., 4: 127-141. Typically one assumes that the two horizontal in-situ stresses 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 offshore 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.