The cave is the main reserve space in fracture-cavity carbonate reservoir. The basic method of fracture-cavity reservoirs exploitation is to generate hydraulic fractures connecting the boreholes and caves through hydraulic fracturing. Based on the TOUGH-AiFrac coupling solver

the influence of different water injection pressures and internal pressure of caves on hydraulic fracture propagation is studied respectively. The results show that with the increase of water injection pressure

the influence of in-situ stress on hydraulic fractures is gradually weakened

and the fractures tend to initiate and propagate along the initial direction. When the water injection pressure is 1.6 times greater than the horizontal maximum principal stress

the rangeability of the fracture initiation directions weaken obviously

and the fracture direction tends to be stable. When the water injection pressure is 2.4 times greater than the horizontal maximum principal stress

the fracture propagation path tends to be stable. The greater internal pressure of the caves

the stronger the cave’s effect on hydraulic fractures. The caves with internal pressure reaching two times of the maximum principal stress exert a kind of “attraction” effect on the hydraulic fractures

which will be gradually strengthened with the increase of cave’s internal pressure while be weakened with the increase of injection pressure. The research results can be used as a guideline to optimize the fracturing work parameters and thereby enhance the oil/gas production rate according to the geological conditions.