不同渗透性储层Biot系数测试方法研究及其影响因素分析

RESEARCH ON TESTING METHODS OF BIOT COEFFICIENT IN RESERVOIR WITH DIFFERENT PERMEABILITY AND ITS INFLUENCING FACTORS

对不同渗透性天然岩芯分别以Cross-plotting法、排水实验法与声波动态法测试其Biot系数,结果表明,对于中高渗岩芯,其结果为k e a?>?>?(k?为Cross-plotting法Biot系数值,e?为排水实验法Biot系数值,a?为声波动态法Biot系数值),而低渗岩芯则无法通过排水实验法获取Biot系数。Cross-plotting法测试结果表明,高渗岩芯Biot系数为0.90~1.00内,中渗岩芯为0.80~0.90,而低渗岩芯Biot系数为0.60~0.75。砂岩等中高渗岩芯推荐用排水实验法获得Biot系数,而低渗岩芯则推荐通过Cross-plotting法测试Biot系数。最后,讨论Biot系数的影响因素。

How to reasonably determine the Biot coefficient of reservoir is rather essential for wellbore stability analysis. This study tests the Biot coefficient of natural cores with different permeability through respectively Cross-plotting method,drainaging experimentation and sonic dynamic method. The results show that it is k e a? >? >? for cores with middle and high permeability(k? is Biot coefficient by Cross-plotting experiment,e? is Biot coefficient by drainage experiment,a? is Biot coefficient by sonic dynamic experiment),while due to poor flowing capacity low permeability cores cannot get the Biot coefficient by the drainaging experimentation;taking the result of Cross-plotting method as the example,Biot coefficient for cores with high permeability distributes in the range of 0.90 to 1.00,that for cores with middle permeability is between 0.90 to 0.80,and that for low permeability is from 0.60 to 0.75;besides,it is recommended that under the allowed experimental conditions cores with middle or high permeability such as sandstones can obtain Biot coefficient by the drainaging method,while cores with low permeability such as shale,tight gas rocks should test Biot coefficient by the Cross-plotting method;finally,it discusses the factors from internal and external aspects on Biot coefficient. The research results will provide a good theoretical support for the analysis on the wellbore stability in deep and ultra deep wells.