On the Problem of Uncertainty in Rock Properties in the In-Situ Stress Profiles Reconstruction Problem

In-situ stresses estimation is an important problem in reservoir geomechanics. Its solution is complicated due to a number of factors including the uncertainty in input data regarding mechanical properties. The current paper highlights the interrelationship between quality of elastic moduli model for the layered rock mass and horizontal stresses on the example of one oil field located in the Republic of Tatarstan. Horizontal stresses are reconstructed from mechanical properties and leak-off tests results via a certain approach based on continuity of layered rock mass. Uncertainty assessment is performed through a series of Monte Carlo simulations with varied elastic moduli model. Input data variation is completed with regard to statistical laws following Pearson distributions obtained for triaxial loading tests results. The layered rock mass is divided into several groups based on detailed core analysis; each group is studied separately. The influence of uncertainty in the mechanical properties of rocks on the results of stress state reconstruction was investigated. The ambiguity of the choice of solutions to the inverse problem of finding a pair of optimal horizontal stresses was also considered.