Experimental research on flow conductivity of different firmness coal rock embedded by proppant

In the process of well fracturing for CBM formations, proppant embedment in coal rock can affect fracture flow conductivity and the development of CBM. In order to study proppant embedment in different firmness coal rock and flow conductivity, the coal rock firmness coefficients in representative fields were measured. Proppant embedment and fracture flow conductivity experiments were conducted with LD-1A proppant conductivity testing system. The result shows that the firmness coefficients of Duanshi, Longmenta and Zhaiyadi coal rocks are 1.4, 0.4 and 0.5, the depth of proppant embedment in Liulin Longmenta coal rock is 0.5 mm, and the degree of flow conductivity damage by proppant embedment can reach 40%, when the closure pressure is 35 MPa. The firmness coefficient of different coal rock differs greatly. The smaller the firmness coefficient is, the deeper the proppant embedment in the coal rock will be, and the greater the degree of fracture flow conductivity damage will be. With the experimental data and production experience, the study has some reference for fracturing practice in field.