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中国石油 塔里木油田分公司 勘探开发研究院, 新疆 库尔勒 841000
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中国石油 塔里木油田分公司 勘探开发研究院, 新疆 库尔勒 841000
Geomechanics modeling of ultra-deep fault-controlled carbonate reservoirs and its application in development
Research Institute of Petroleum Exploration & Development, PetroChina Tarim Oilfield Company, Korla, Xinjiang 841000, China
Research Institute of Petroleum Exploration & Development, PetroChina Tarim Oilfield Company, Korla, Xinjiang 841000, China
为提高超深断控碳酸盐岩油藏的开发效益,通过开展大尺寸岩样力学实验,揭示高角度-近直立断裂面变形与连通机理;基于高压注水提采的力学与流动耦合原理,通过地质力学建模,明确了断控碳酸盐岩油藏现今地应力场和断裂活动性分布规律;发现不同方位的断裂活动性以及不同部位的缝洞体连通性有明显差异,进而分析了不同井眼轨迹的开发效果,提出了地质工程一体化工作方法,科学指导井眼轨迹设计和注水方案优化。结果表明:①走滑断裂变形中的大尺度破碎体和高角度裂缝系统是影响储层品质的关键因素,高压注水一方面能够激活先存裂缝,一方面还能在先存裂缝基础上发生延伸扩展,甚至可以产生新的裂缝,促进了断控缝洞体在纵横向上的互相连通;②高压注水过程中断裂体内部发生力学与流动之间的耦合变化,渗流环境得到改善,通过循环举升,从而提高油气采收率;③根据断裂体形态、产状以及断裂面动态剪切变形连通性,可优选定向井最佳井点和井眼轨迹,并优化注水方案;④塔里木盆地断控油藏试验区通过高压注水,采收率提高5个百分点,该方法为超深断控型油藏高效开发提供了较好的理论依据和技术支撑。
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.