致密储集层应力敏感性评价  

Evaluation of the stress sensitivity in tight reservoirs

作　　者：肖文联[1] 李滔[1] 李闽[1] 赵金洲[1] 郑玲丽[1] 李铃[1] 

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室

出　　处：《石油勘探与开发》2016年第1期107-114,共8页Petroleum Exploration and Development

基　　金：国家自然科学基金项目"鲕粒灰岩渗透率非线性有效应力研究"(41404083)和"充填粘土裂缝砂岩N-ESLK理论与实验研究"(51274169);国家重点基础研究发展计划(973)项目"陆相致密油高效开发基础研究"(2015CB250900)

摘　　要：通过对比分析表征岩石渗透率与有效应力关系的经验模型与理论模型,得到3种应力敏感系数(S、α、β)的表达式;结合实验数据和岩石微观结构特征,提出致密砂岩应力敏感性划分标准。用经验模型与理论模型分析致密砂岩和不同类型花岗岩渗透率与有效应力的实验数据,进一步明确经验模型以及应力敏感系数的物理含义,并计算岩石的3种应力敏感系数,仅S中不含不确定指数n,具有明确的物理意义。基于3种应力敏感系数特征、渗透率与有效应力关系的研究,发现可用应力敏感系数S划分储集层岩石的应力敏感性:S>0.40为强应力敏感性;S<0.25为弱应力敏感性;0.25≤S≤0.4为中等应力敏感性,强应力敏感性岩心更满足对数模型,弱应力敏感性岩心更满足指数模型和二项式模型,中等应力敏感性岩心满足乘幂模型。结合岩石的微观特征讨论了应力敏感性划分标准的适应性,发现强应力敏感性岩石裂缝性特征明显,而弱应力敏感性岩石具有孔隙性特征;此外,黏土胶结物的类型、岩石颗粒大小以及岩性也影响岩石的应力敏感性。The expressions of three types of stress sensitivity coefficients （S, α、β） are obtained on the basis of analysis of the empirical models and theoretical models on the relationships between permeability and effective stress, and the stress sensitivity evaluation standard is proposed considering experiment data and rock micro-structural features. Then the empirical models and theoretical models were used to fit experiment data of low-permeability and tight sandstones and different types of granites, which promotes the understanding of the empirical models and the physical meanings of the stress sensitivity coefficients. According to the study of the three types of stress sensitivity coefficients and the relationship of effective stress and permeability, it is found that the stress sensitive coefficient S was suitable for evaluating the stress sensitivity （strong stress sensitivity： S〉0.40; low stress sensitivity： S〈0.25; medium stress sensitivity： 0.25≤S≤0.4）. Meanwhile, it is also found that strong-stress-sensitivity cores are more suitable to be characterized by the logarithmic model, while the exponential model （or binomial model） occurred more frequently in low-stress-sensitivity cores, and medium-stress-sensitivity cores are more likely to be described with the power model. Finally, the evaluation standard is discussed based on the micro-structure in the low-permeability and tight sandstones. The results show that the crack-like pores in the strong-stress-sensitivity cores are obvious, but low-stress-sensitivity cores have the characteristics of porous rocks; moreover, the types of cemented clay minerals, the size of rock grain and lithology have impact on stress sensitivity.

关 键 词：致密砂岩 应力敏感性 应力敏感系数 有效应力 渗透率 微观结构 

分 类 号：TE348[石油与天然气工程—油气田开发工程]