煤样渗透率有效应力与基质收缩双重耦合效应及其与煤阶关系  

The dual coupling effect of coal sample permeability effective stress and matrix shrinkage and its relationship with coal rank

作　　者：曹明亮 邓泽 康永尚[3] 李忠城[1] 张兵[1] 秦绍锋[1] 邓志宇[1] 郭明强[1] CAO Mingliang;DENG Ze;KANG Yongshang;LI Zhongcheng;ZHANG Bing;QIN Shaofeng;DENG Zhiyu;GUO Mingqiang(China United Coalbed Methane Corporation,Ltd.Beijing,100016;Key Laboratory of Unconventional Oil and Gas,China National Petroleum Corporation,Langfang,Hebei,065000;College of Geosciences,China University of Petroleum(Beijing),Beijing,102249)

机构地区：[1]中联煤层气有限责任公司,北京100016 [2]中国石油天然气集团有限公司非常规油气重点实验室,河北廊坊065000 [3]中国石油大学(北京)地球科学学院,北京102249

出　　处：《地质论评》2022年第5期1863-1870,共8页Geological Review

基　　金：国家重大专项(编号:2016ZX05041-001)的成果。

摘　　要：为研究煤层气在排采过程中不同煤阶煤储层渗透率动态变化规律,利用煤岩三轴应力应变(基质收缩膨胀)测试系统,对褐煤、气煤和无烟煤样开展了有效应力与基质收缩双重效应物理模拟实验。固定轴压和围压不变,改变气体平衡压力,模拟开发过程中储层压力变化特征,测试其动态渗透率。利用实验结果,分析了不同煤阶煤岩在排采过程中动态渗透率反弹特征,并对比分析煤岩动态渗透率改善效果的差异性。研究表明:气体平衡压力从5 MPa降至1 MPa过程中,在有效应力和基质收缩双重效应作用下,褐煤样的归一化渗透率依次为1.00、0.60、0.57、0.57、0.52,气煤样依次为1.00、0.64、0.50、0.54和0.55,无烟煤样依次为1.00、0.74、0.58、0.50和0.56。随气体平衡压力下降,中阶及高阶煤样动态渗透率先下降后上升,整体呈不对称“V”型变化规律,但拐点略有不同;低阶煤样动态渗透率呈先下降后基本稳定的趋势,整体呈斜“L”型变化规律。在有效应力和基质收缩双重效应影响下,中阶及高阶煤样动态渗透率改善效果优于低阶煤样。In order to study the dynamic permeability changes of coal reservoirs of different coal ranks during drainage and production,the coal rock triaxial stress—strain(matrix contraction and expansion) test system was used to carriy out physical simulation experiments on the dual effects of effective stress and matrix shrinkage on lignite,gas coal and anthracite.Fixing the axial pressure and confining pressure unchanged,changing the gas balance pressure,simulating the characteristics of the reservoir pressure change during the development process,and testing its dynamic permeability.Using experimental results,the rebound characteristics of dynamic permeability of coals of different ranks during drainage and production are analyzed,and the differences in the improvement effects of dynamic permeability of coals are also analyzed.Research shows that:In the process of reducing the gas balance pressure from 5 MPa to 1 MPa,under the dual effects of effective stress and matrix shrinkage,the normalized permeability of lignite coal sample were 1.00,0.60,0.57,0.57,0.52 in sequence,gas coal sample were 1.00,0.64,0.50,0.54,and 0.55,the anthracite coal sample were 1.00,0.74,0.58,0.50,and 0.56.As the gas equilibrium pressure decreases,the dynamic permeability of the coal samples of middle-rank and high-rank declines first and then rises,and the overall is asymmetrical "V" type change law,but the inflection point is slightly different.The dynamic permeability of low-rank coal sample shows a trend of first decreasing and then basically stable,and the overall is oblique "L".Under the influence of the dual effects of effective stress and matrix shrinkage,the dynamic permeability improving effect of the middle-rank and high-rank coal samples is better than that of low-rank coal sample.

关 键 词：煤岩 有效应力 基质收缩 动态渗透率 物理模拟 

分 类 号：P618.13[天文地球—矿床学]