摘要
储层的应力敏感问题是近年来石油工程领域的研究热点之一,但对"低渗透储层是否存在强应力敏感",石油学界存在2种相反的观点,且争议不断,给油气生产和决策带来困扰。通过剖析应力敏感实验研究的局限,并根据应力敏感评价理论计算结果,对"低渗透储层存在强应力敏感"的观点提出了质疑。应力敏感实验测试存在难以模拟储层实际受力状态、微间隙影响实验结果、不同渗透率岩心测试稳定时间差异大等问题,实验结果难以反映岩石渗透率的真实特性;对实验结果进行分析时,错误使用Terzaghi有效应力,放大了储层的应力敏感程度。以双重有效应力和多孔介质弹性力学理论为基础,应用管流来模拟实际岩石中的渗流,从岩石力学角度推导出储层应力敏感评价的理论计算公式。计算结果表明,低渗透储层不存在强应力敏感。研究结果对于指导低渗透油藏开发具有重要意义。
The stress sensitivity of reservoir is one of the research hotspots in petroleum engineering in recent years.However,there are two opposite viewpoints and many disputes about"whether there is strong stress sensitivity in low permeability reservoir",which bring troubles to oil and gas production and decision making. Based on the analysis of the limitation of stress sensitivity experimental research and the theoretical calculation results of stress sensitivity evaluation,the viewpoint"strong stress sensitivity exists in low permeability reservoir"was questioned. There are many problems in the stress sensitivity experiment,e.g.,the actual stress state of reservoir is hard to be simulated,the microclearance affects the experimental results,and the stabilization time of core test with different permeability varies greatly,so the experimental results can hardly reflect the true characteristics of rock permeability; moreover,when the experimental results are analyzed,the Terzaghi effective stress is misused,which magnifies the stress sensitivity of the reservoir. Based on the theory of double effective stress and elastic mechanics of porous media,pipe flow was used to simulate the seepage in real rock,and the theoretical calculation formula of reservoir stress sensitivity evaluation was derived from the perspective of rock mechanics. The calculation results show that there is no strong stress sensitivity in low permeability reservoirs. The study results are of great significance for guiding the development of low permeability reservoirs.
引文
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