STUDY ON THE VARIATION LAW OF CRUSTAL STRESS FIELD IN TIGHT RESERVOIR UNDER MULTI FIELD COUPLING

Crustal stress is an important index of reservoir reconstruction scheme design and improvement to oil and gas exploration and development efficiency. Due to the complex environment in which tight reservoirs are located, the multi field coupling of temperature, stress and seepage should be considered comprehensively. Therefore, the tight reservoir in Block 4 three-dimensional area of central Junggar Basin was taken as an example, the THM coupled control equation was established based on the COMSOL Multiphyics software, and the variation law of crustal stress field in tight reservoir under multi field coupling was studied. The result shows that:The maximum horizontal principal stress ranges from 113 to 134 MPa, and the minimum horizontal principal stress from 106 to 124 MPa, all showing as compressive stress. In the process of oil and gas exploitation, the maximum horizontal principal stress increases first and then tends to be stable. With the deepening of oil and gas exploitation, the range of stress change gradually extends from the wellhead to the nearby fault, and preferentially develops along the fracture direction of the fault. In the fault transition zone, the stress value is minimum, and the stress at the core of the fault is between the broken transition zone and the continuous stratum. With the deepening of oil and gas exploitation, the vertical deformation will occur in tight reservoirs. The maximum vertical deformation of the reservoir occurs near the wellhead, the displacement is more than 10cm, and the settlement decreases as the distance increasing.