长庆致密碎屑岩储集层应力敏感性分析

Stress sensitivity analysis of Changqing tight clastic reservoir

使用CMS 3 0 0岩心自动分析仪 ,定量研究了长庆气田上古生界致密碎屑岩天然气储集层的应力敏感性 ,结果表明 :岩心分析孔隙度、渗透率 (y)与净覆压 (x)的关系符合通常的幂指数函数模式 (y =a/xm) ,不同岩样的回归指数 (m )和系数 (a)高度相关 ;一般地层条件下的分析渗透率为地面渗透率的 5 %～80 % ,而孔隙度绝对值平均降低了 0 .4% ;岩石应力敏感性的强弱与基础的岩性、物性有关 ,一般岩屑砂岩和含泥砂岩比石英砂岩强 ,砾岩比砂岩强 ,低渗透砂岩比高渗透砂岩强。

Stress sensitivity of Changqing tight clastic gas reservoir is studied quantitatively by CMS-300, which is a auto core analysis instrument. The results indicate that :(1)The relationship between stress(independent variable,x) and permeability /porosity (dependent variable, y) is extremely accord with exponent function mode, which is y=a/x^m and a is highly related to m with different core samples; (2)Commonly,the permeability in formation condition is 5%-80% of that in surface condition,for porosity, the value averagely decreases 0.4%; (3)The stress sensitivity is related to lithological and physical propert ies; generally, litharenite sands tone is more sensitive than quartzy sandstone, conglomerate than sand and the lo w permeability than the high permeability.