摘要
试验设计多个回路,各个回路的孔隙流体压力不同,每一回路在孔隙流体压力不变,增加和降低围压方式下进行。试验过程中采用稳态法测定不同围压和孔隙流体压力下的岩芯渗透率,并用响应面法对试验结果进行处理分析。结果表明,有效应力系数α随围压和孔隙流体压力的变化而变化。当围压很大时,试验研究得到的有效应力系数很小,这与过去试验研究的结果差别很大。最后用有效应力系数α=1.0和本次试验获取的有效应力系数对低渗砂岩岩样进行应力敏感性评价。用有效应力系数α=1.0评价的结果是储层存在强应力敏感,而用本次试验获取的有效应力系数的评价结果是储层表现为弱应力敏感性。
The experiments included many cycles from which the pore fluid pressures were different. Each cycle run under constant pore fluid pressure by increasing or decreasing confining pressure. Experimental data were dealt with by steady state method, and analyzed with response-surface method. It was found that the effect stress coefficient α varied with pore fluid pressure and confining pressure. At the higher confining pressures in the test, all of the coefficient α were below 0.11, which was contrary to conventional view. In order to analyze the stress-sensitivity of low-permeability sandstone sample, coefficient α=1.0 and coefficient α obtained from the experiment were adopted. It was shown that permeability stress sensitivity was very strong as conventional α = 1.0 was used while hardly existed as the effective-stress coefficient α adopted from the experiment was used.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2008年第A02期3535-3540,共6页
Chinese Journal of Rock Mechanics and Engineering
基金
国家重点实验室开放式基金项目(PLN0802)
关键词
岩石力学
有效应力
敏感指数
有效应力系数
响应面
最大似然函数
rock mechanics
effective stress
sensitivity index
effective-stress coefficient
response surface
maximum-likelihood approach
