Distribution characteristics and disturbance mechanism of geostress field in complex fault zone: A case study of Upper Paleozoic in Dingbei area of Ordos Basin

Objective Dingbei area is rich in tight gas resources of Upper Paleozoic and has great exploration potential. However, faults are widely developed in this area, and the characteristics of geostress field near the fault zone are unknown, which seriously restricts oil and gas exploration and development in this area. Methods Therefore, this paper conducts a detailed analysis of the characteristics of the Upper Paleozoic geostress field in the study area based on differential strain experiment, acoustic emission experiment, logging interpretation of geostress size, wave velocity anisotropy experiment, paleomagnetism experiment, imaging logging and dipole acoustic logging data interpretation of geostress direction, numerical simulation and other methods, in order to find out the distribution characteristics and disturbance mechanism of the geostress field in Dingbei area. ResultsThe research shows that the three-dimensional stress of Upper Paleozoic in Dingbei area has the characteristics of vertical principal stress > maximum principal stress > minimum principal stress, and the regional geostress field is mainly controlled by the fault zone, and the stress disturbance degree is related to the fault location, fault scale, fault genesis and other factors, among which the three-dimensional stress in the karst fault zone is relatively lowest. The direction of regional principal stress field is N35°E~N45°E. The direction of reservoir geostress is mainly controlled by the direction of regional principal stress field and fault zone, and the range and degree of geostress disturbance caused by different types of fault zones are different, among which the range of geostress disturbance is mainly affected by fault strike and fault length.ConclusionsBased on the research on the characteristics of geostress field, this paper clarifies the distribution characteristics and disturbance law of geostress size and direction in Dingbei area, discusses the disturbance mechanism of different genetic fault zones on geostress size, and establishes a prediction model for the disturbance width of geostress direction in the research area, which has important reference value for subsequent well pattern deployment and fracturing reconstruction.