Muhammad Usman Tahir, Shenglan Guo
The low concentration and poor reservoir properties of natural hydrogen suggest that reservoir stimulation measures such as fracturing is required for its efficient development. Nevertheless, the presence of reservoir imperfections, including hard and soft cores, can significantly affect fracture behavior during the fracturing operations. Moreover, there is currently a lack of relevant simulation and experimental studies addressing these effects. In the present work, the effects and mechanisms of hard cores on fracture propagation in natural hydrogen reservoirs in the Songliao basin were numerically simulated. In addition, various factors affecting propagation behavior of fracture were also analyzed. The investigation results indicate that the presence of hard cores induces the fracture propagation mode from “straight-line dominated” to “path optimization” (obstacle-avoidance) pattern, which consequently decreases propagation efficiency. The final fracture length exhibits a reduction of 12.63% compared with that in the homogeneous reservoir case, accompanied by an increase of 18.49% in the final fracture width. Furthermore, higher hard core strength and leakage coefficients significantly decrease fracture propagation efficiency, promoting the development of wide, short fractures. This research offers a preliminary theoretical framework to support the stimulation and efficient development of imperfection-bearing natural hydrogen reservoirs.