井周煤层气渗流及恒压下煤岩力学特性试验  

Experimental study on gas flow and mechanical behaviors of coalbed near borehole under constant flow and CBM pressures

作　　者：张千贵[1,2] 范翔宇[2] 陈平[2] 李广治[1] 李铭辉[1] 马天寿[2] 

机构地区：[1]重庆大学煤矿灾害动力学与控制国家重点实验室,重庆400030 [2]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500

出　　处：《中国石油大学学报（自然科学版）》2015年第5期94-101,共8页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家自然科学基金项目(51474185);国家'973'计划项目(2013CB228003);煤矿灾害动力学与控制国家重点实验室自主研究项目(2011DA105287-FW201203);中国博士后科学基金项目(2014M560728)

摘　　要：利用自行研制的含瓦斯煤热流固耦合三轴伺服渗流试验装置,进行0.5和1.0 MPa煤层气渗流压力、0.5和1.0 MPa煤层气恒定压力条件下原煤样全应力-应变过程三轴压缩试验,研究井周煤层气渗流特征及煤层气渗流与恒压对煤岩力学性质的影响。结果表明:煤岩渗透系数和煤层气流量随轴向应变增加先降低,在屈服点减小到最低点后逐渐增大,最后趋于稳定;煤层气恒压下的煤岩三轴抗压强度、屈服强度、弹性模量显著低于相应煤层气渗流压力下的值;恒定煤层气压力越大,煤岩三轴抗压强度、屈服强度和弹性模量越小;煤层气渗流压力越大,煤岩三轴抗压强度、屈服强度、弹性模量越小;研究结果可为煤层气欠平衡钻井压力控制、固井及储层改造等设计与施工提供技术支持。The flow behavior of coalbed methane ( CBM) and its influence on the mechanical properties of coal at near well-bore region were conducted under different pressures using a self-designed 'tri-axial stress gas permea-meter' for CMB tes-ting. The experiments were carried out under gas flow pressures of 0. 5 MPa and 1. 0 MPa and constant CBM reservoir pres-sures of 0. 5 MPa and 1. 0 MPa,respectively. The experimental results show that with the increase of the axial pressure or strain, the coal's permeability and gas flow both decrease gradually firstly, and reach the lowest point at yield point, then in-crease to a stable value finally. The strength, yield strength and elasticity modulus of coal samples under a constant CBM res-ervoir pressure are all smaller than those under corresponding gas flow pressures. Under constant CBM reservoir pressure or gas flow pressure, the bigger these pressures are, the smaller the shear strength, yield strength and elasticity modulus of coalbed around the wellbore will be. These observations can be useful for pressure control during operations of unbalanced drilling, well completion and reservoir stimulation.

关 键 词：岩石力学 煤层气 煤岩渗透率 力学性质 欠平衡钻井 

分 类 号：TE21[石油与天然气工程—油气井工程]