裂缝性致密油藏注水吞吐转不稳定水驱开发模拟

为解决裂缝性致密油藏经多轮次吞吐后,产量降低过快的问题,以天然裂缝较为发育的某致密油藏M区块为例,综合考虑基质、天然裂缝和压裂裂缝的物性和压力差异,开展了数值模拟研究,分析了裂缝尖端应力场和裂缝扩展特征.在此基础上,对比分析了注水吞吐、不稳定水驱的开发效果.结果表明,地层压力随注水时间延长逐渐升高,当地层压力高于裂缝开...

Simulation of Transformation from Water-Injection Huff and Puff to Unstable Water-Flooding in Developing Fractured Tight Reservoirs

Multiple rounds of huff and puff in tight reservoirs usually lead to a rapid decrease in production. Taking the M block of a tight reservoir with developed natural fractures as an example, a numerical simulation was conducted based on the physical properties of the matrix, natural fractures, and fractured fractures as well as the pressure difference to analyze the stress field of fracture tips and the features of fracture propagation. On this basis, a comparative analysis was then carried out to evaluate the development effect of water-injection huff and puff and unstable cyclic water injection. Results show that the formation pressure would grow with an increase in water injection time, and when the formation pressure was higher than the opening pressure of fractures, a complex and dynamic fracture network was formed with the expansion of natural fractures and the communication of fractured fractures. Unstable water-flooding can give full play to imbibition and displacement, and the change of water injection volume can effectively avoid water channeling and form relatively uniform flooding front. In addition, simulation results show that a significant increase of 18% in cumulative oil production of reservoirs with cyclic water injection compared with water-injection huff and puff. Therefore, transforming the development method into unstable water-flooding can effectively improve the oil production of horizontal wells in fractured tight reservoirs, providing a theoretical reference for optimizing the development of horizontal wells in tight reservoirs.