Abstract：In exploration and production of oil and gas reservoir，the determination of in-situ stress orientation is essential for the distribution of natural fracture，arrangement of water flooding wells，design of horizontal well and water fracturing，optimal program of water injection and oil development adjustment. The paleomagnetic method for the determination of maximum horizontal stress orientation is introduced. The original orientation of the core in the reservoir formation can be obtained by paleomagnetic orientation of cores，and the relative orientation of maximum horizontal stress to the datum line in cores can be obtained by using the Kaiser effect of acoustic emission of rocks. Combining paleomagnetic orientation of cores with Kaiser effect of acoustic emission，the original orientations of the maximum horizontal stresses in the reservoir formation are then obtained. The results by the presented method are fundamentally consistent with diplog in a case in Jing’an oil field.
