CDEM-based simulation of the 3D propagation of hydraulic fractures in heterogeneous Coalbed Methane reservoirs

To simulate the propagation law of hydraulic fractures in deep Coal Bed Methane (CBM) reservoirs Qin-shui basin, a 3D numerical model is established using continuous-discontinuous algorithm, and discrete fracture network (DFN) included to increase its heterogeneity. The control variable method was employed study effects situ stress, random number, fracturing fluid flow viscosity on propagation. results show that surface can extended rapidly upper lower boundaries model, then extend two ends perpendicular minimum principal stress. Simultaneously, there also short-distance extension along direction width horizontal section oval, is, at injection point largest, decreases gradually process extending forward. pressure data decrease expansion process. With an buried depth coal seam, sharply increases, while decreases. will be conducive only when angle between strike maximum stress very small “hinder” most cases. greater density reservoir more obvious “blocking” effect smaller fractures. significantly affect speed change shape from “oval” “round”, which not Volume heterogeneity introduced quantitatively determine characteristics multiple regression analysis used obtain relationship among length, volume heterogeneity, depth, time low water as fluid. It determined reservoirs, burial (in stress), rate are main controlling factors affecting length width.