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

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.