煤岩裂缝渗流能力实验评价及近井地层等效渗透率分析  

Experimental Evaluation on Seepage Capability of Coal Rock Fractures and Near-well Formation Equivalent Permeability Analysis

作　　者：张亮[1,2] 魏虎超[1,2] 王得志 王伟 杨红斌 郝永卯[1,2] 战永平 任韶然[1,2] ZHANG Liang;WEI Hu-chao;WANG De-zhi;WANG Wei;YANG Hong-bin;HAO Yong-mao;ZHAN Yong-ping;REN Shao-ran(School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,China;Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)),Ministry of Education,Qingdao 266580,China;Hancheng Branch,Coalbed Methane Company,CNPC,Xi an 715400,China)

机构地区：[1]中国石油大学(华东)石油工程学院,青岛266580 [2]非常规油气开发教育部重点实验室(中国石油大学(华东)),青岛266580 [3]中石油煤层气公司韩城分公司,西安715400

出　　处：《科学技术与工程》2021年第2期495-503,共9页Science Technology and Engineering

基　　金：中央高校基本科研业务费专项(18CX05009A);“十三五”国家科技重大专项(2016ZX05056004-003)。

摘　　要：煤岩裂缝的渗流能力是影响煤层气产能的重要因素。采用API导流仪及岩心驱替装置,模拟煤层气排采过程中煤层有效应力的连续变化,评价裂缝闭合压力逐渐升高、地层压力连续下降以及频繁开关井(间歇性排采)等工况条件下煤岩压裂裂缝的动态导流能力和含天然裂缝煤心的渗透率变化。实验结果表明,提高裂缝闭合压力、降低孔隙流体压力以及频繁开关井等都会降低煤岩裂缝的渗流能力,尤其对压裂裂缝的导流能力影响更为显著。基于此,利用实验数据分别回归了煤岩压裂裂缝导流能力和含天然裂缝煤岩渗透率与有效应力的经验关系式,建立近井煤层等效渗透率计算模型。利用该模型可以根据现场测算的等效渗透率,初步判断煤层压裂裂缝的有效导流能力或缝长,可以为煤层气压裂效果评价、分析排采过程中煤岩裂缝参数的动态变化提供一种新方法。Seepage capability of coal rock fracture is an important parameter which can influence coalbed methane production signi-ficantly.The dynamic conductivities of hydraulic fractures and the permeability change of coal rock with natural fractures were evaluated by using the API fracture conductivity equipment and core-flooding equipment,respectively.The experimental results show that increasing the closure pressure of fracture,decreasing the porous fluid pressure,and switching well frequently can reduce the seepage capability of fracture in coal rock,and the conductivity of hydraulic fracture is more easily affected by these factors.Based on this finding,according to the experimental results,the empirical formula of the relationship between the hydraulic fracture conductivity and permeability of coal rock with natural fracture and the effective stress are regressed,and a calculation model of the equivalent permeability of the coal layer near well is established.The model can be used to estimate the effective conductivity or the length of the hydraulic fracture,which can provide a new method for evaluating the hydraulic fracturing performance of coalbed methane and analyzing the dynamic changes of coal fracture parameters in the process of coalbed methane production.

关 键 词：煤岩 压裂裂缝 不合理排采 导流能力 等效渗透率 

分 类 号：TD823[矿业工程—煤矿开采]