渗透率应力敏感实验假象剖析

Analysis of false impression of permeability stress sensitivity experiment

周鹏高 2

克拉玛依职业技术学院石油工程系，新疆 克拉玛依 834000 中国地质大学（北京）自然资源部深部地质钻探技术重点实验室，北京 100083

Department of Petroleum Engineering, Karamay Vocational & Technical College, Karamay 834000, China Key Laboratory of Deep GeoDrilling Technology of Ministry of Natural Resources, China University of Geosciences, Beijing 100083, China

储层渗透率的应力敏感问题是近年来石油工程领域的研究热点之一。应力敏感研究主要依靠实验测试，根据实验结果，“低渗透储层存在强应力敏感，且岩石渗透率越低，应力敏感性越强”的观点得到广泛认同。文中通过深入分析有效应力理论和微间隙对实验结果的影响，对应力敏感实验假象进行了全面剖析。对比不同的有效应力理论发现，实验研究过程中错误选用Terzaghi有效应力，放大了岩石渗透率的应力敏感性。定性分析微间隙的影响，并结合定量计算，发现微间隙对渗透率的测试结果及变化规律具有重要影响。渗透率越低，微间隙的影响作用越大，微间隙是造成岩石应力敏感性被高估的重要原因。理论研究结果否定了“岩石渗透率越低，应力敏感性越强”的观点；定量计算结果表明，低渗透储层不存在强应力敏感。

Stress sensitivity of reservoir permeability is one of the hot topics in petroleum engineering in recent years. Stress sensitivity research mainly depends on experimental testing. According to the experimental results, the viewpoint of "strong stress sensitivity in low permeability reservoirs, and the lower the permeability, the stronger the stress sensitivity" has been widely accepted. Through in-depth analysis of the effective stress theory and the effect of micro-gap on the experimental results, the stress-sensitive experimental illusion was analyzed comprehensively. Compared with different effective stress theories, Terzaghi effective stress was chosen incorrectly in the experimental study, which enlarged the stress sensitivity. Qualitative analysis and quantitative calculation show that micro-gaps have an important influence on the permeability test results and change rules. The lower the permeability, the greater the effect, micro-gaps are the important reasons for the overestimation of stress sensitivity. The theoretical research results negate "the lower the rock permeability, the stronger the stress sensitivity". The quantitative calculation results show that there is no strong stress sensitivity in low permeability reservoirs.

10.6056/dkyqt201903021