不同类型压裂返排液对煤层气储层的伤害实验研究

Experimental study on damage of different types of fracturing flow-back fluid to coalbed methane reservoir

为了明确压裂返排液对煤层气储层的伤害情况,选择山西沁水盆地某煤层气矿区储层煤样和不同类型现场压裂返排液为研究对象,通过煤岩心驱替实验、煤储层裂缝导流能力实验以及煤层气解吸实验评价了不同类型压裂返排液对煤层气储层的伤害情况。结果表明:经过不同类型的压裂返排液污染后,目标区块煤层气储层煤岩心渗透率、裂缝导流能力和煤层气解吸能力均有不同程度的下降现象,其中线性胶压裂返排液对煤层气储层的伤害程度最大,清洁压裂返排液次之,活性水压裂返排液的伤害程度最小;结合不同类型压裂返排液的基本性能评价情况,认为压裂返排液对煤层气储层的伤害原因主要包括固相颗粒堵塞损害、微粒运移堵塞损害和水锁损害等。

In order to make clear the damage of fracturing fluid to coalbed methane reservoir,the coal samples and different types of field fracturing fluid in a coalbed methane mining area in Qinshui Basin,Shanxi Province were selected as the research objects.Through the coal core displacement experiment,coal reservoir fracture conductivity test and coalbed methane desorption experiment,the damage of different types of fracturing backflow fluid on coalbed methane reservoir was evaluated.The results show that:after polluting different types of fracturing flow-back fluid,the permeability of coal core,fracture conductivity and desorption capacity of coalbed methane reservoir in the target block all decrease to varying degrees,in which the damage degree of linear fracturing flow-back fluid to coalbed methane reservoir is the largest,followed by clean fracturing flow-back fluid,and the damage degree of active hydraulic fracturing flow-back fluid is the smallest.According to the basic performance evaluation of different types of fracturing flow-back fluid,the damage causes of fracturing flow-back fluid to coalbed methane reservoir mainly include solid particle plugging damage,particle migration plugging damage and water lock damage.