Assessment of the In-situ Stress State of the Carbonate Rock Mass at an Oil Field

The paper presents an algorithm for reconstruction of stress state parameters of rock massif based on data on natural fractures. For one well developing an oil field, the directions of the principal in-situ stresses, their relative magnitudes, and the strength of the rocks in the near-wellbore space were reconstructed. Stress inversion results are in agreement with other methods of stress estimation, in particular, with the results of the mini-hydraulic fracture test. The inverse problem of stress state estimation is solved using the Monte Carlo method. An algorithm of applying the apparatus of mathematical statistics – the method of moments for determining distribution parameters from the Pearson distribution family – to quantify the ambiguity of the estimation of the directions of the principal stresses and their relative magnitudes is presented. The proposed algorithm can be used for independent reconstruction of stresses for carbonate rocks, provided that there is information about the conductivity of fractures in the rocks of the near-wellbore space to further improve the quality of one-dimensional and three-dimensional geomechanical modelling.