Study on Wellbore Stability Evaluation Method of New Drilled Well in Old Reservoir

The borehole wall stability of depleted reservoirs is a key problem that restricts the deeper potential exploitation old oilfields. Based on these, according to seepage and elastic mechanics theory porous media, combined with laboratory rock experiments, dynamic evaluation model geomechanical parameters reservoir established, this basis, method wellbore new wells in changing laws influencing factors are quantitatively evaluated. research shows pressure, porosity, effective stress coefficient, strength, situ magnitude, direction were all changed due long-term exploitation; both collapse fracture pressure decreased, loss risk drilling fluid was increased, safe azimuth changed. results can guide reasonable choices such as well position, track mud density, strengthening sealing while order ensure effectively.