Geomechanics modeling of ultra-deep fault-controlled carbonate reservoirs and its application in development

The deformation and connectivity mechanism of high angle near vertical fault surface is revealed through large-scale rock sample mechanical experiments in order to improve the development benefit of ultra-deep fault-controlled carbonate reservoirs. Based on the mechanics and flow coupling principle of high-pressure water injection production, the in-situ stress field and fault activity distribution law of fault-controlled carbonate reser- voirs are clearly determined through geomechanics modeling. It is found that there are obvious differences in fault activity in different directions and fracture cavity connectivity in different parts, and then the development effects of different wellbore trajectories are analyzed. The geology-engineering integration is put forward to scientifically guide the design of wellbore trajectories and the optimization of water injection schemes. The results show that:① Large-scale fractures and high-angle fracture systems in the deformation of strike-slip faults are the key factors affecting reservoir quality. On the one hand, high-pressure water injection can activate preexisting fractures, and on the other hand, it can extend and expand on the basis of preexisting fractures, and even generate new fractures, which promotes the interconnection of the fault-controlled fracture-cavity bodies in the vertical and horizontal direc- tions. ② The coupling change between mechanics and flow occurred inside the fracture body during the process of high pressure water injection, the seepage environment is improved, and the oil and gas recovery factor is improved through cyclic lifting. ③ According to the shape and occurrence of fault body and the dynamic shear deformation connectivity of fault surface, the best well point and well trajectory of directional well can be selected, and the water injection scheme can be optimized. ④ The oil and gas recovery factor of the fault-controlled reservoir test area in the Tarim Basin is increased by five percentage points by high-pressure water injection. This method provides a good theoretical basis and technical support for highly efficient development of ultra-deep fault-controlled oil reservoirs.