由于埋深急剧变化，急倾斜储层煤层气井排采范围内上倾方向与下倾方向（简称“上倾与下倾”）应力变化大，压裂裂缝扩展不同于水平或近水平储层。基于准南阜康西区急倾斜储层现场压裂数据，分析了裂缝扩展过程中井底压力变化和裂缝形态特征，并利用有限元方法研究了急倾斜储层水力压裂过程中的裂缝扩展特征，阐明了倾角（应力梯度）对煤储层裂缝扩展的影响。结果表明：基于上倾与下倾的应力和裂缝扩展特征，可将急倾斜储层划分为浅部急倾斜储层，中部急倾斜储层和深部急倾斜储层；浅部急倾斜储层（垂向应力小于水平应力）裂缝扩展分为裂缝向上倾扩展−裂缝停止扩展−裂缝向下倾扩展3个阶段；中部急倾斜储层（上倾垂向应力小于水平应力，下倾垂向应力大于水平应力）裂缝先向上倾扩展，随后裂缝沿上倾边界及垂向应力大于水平应力处转向垂直于储层倾向方向；深部急倾斜储层（垂向应力大于水平应力）裂缝垂直于倾向方向扩展；随着储层倾角增大，浅部储层上倾扩展速率增大，而下倾降低；中部储层则裂缝逐渐由沿倾向方向扩展转向垂向于倾向方向；急倾斜储层上倾与下倾裂缝扩展差异主要是不同埋深下应力变化引起的破裂压力差异，使裂缝先沿应力低的优势通道扩展。

Due to the rapid changes in burial depth in steeply inclined reservoirs (SICR), there is a significant change in stress in the up-dip and down-dip directions within the drainage range of CBM wells, and the expansion of fracturing fractures is different from that of near horizontal reservoirs. Based on the field fracturing data of steeply inclined reservoirs in Fukang West Block of southern Junggar Basin, this study analyzed the bottom hole pressure and fracture morphology characteristics in the process of hydraulic fracture of steeply inclined reservoirs, studied the fracture propagation characteristics of steeply inclined reservoirs by using the finite element numerical method, and expounded the impact of dip angle (stress gradient) on the fracture propagation of coal reservoirs. The results show that according to the stress and fracture propagation characteristics in the up-dip and down-dip dip directions, steeply dipping reservoirs are divided into shallow-steeply dipping reservoirs, middle-steeply dipping reservoirs, and deep-steeply dipping reservoirs. The hydraulic fracture propagation of shallow-steeply inclined reservoirs (with vertical stress less than horizontal stress) can be divided into three stages: fracture propagation in the up-dip direction, fracture stopping propagation, and fracture propagation in the down-dip direction; the fractures in the middle-steeply inclined reservoirs (with the vertical stress in the up-dip direction is less than the horizontal stress, and the vertical stress in the down-dip direction is greater than the horizontal stress) first expand in the up-dip direction, and then the fractures begin to turn perpendicular to the dip direction along the boundary of the up-dip direction and where the vertical stress is greater than the horizontal stress; deep-steeply inclined reservoirs (with vertical stress greater than horizontal stress) fractures propagate perpendicular to the dip direction. As the dip angle of the reservoir increases, the propagation rate of shallow reservoirs increases in the up-dip direction, while the rate decreases in the down-dip direction; the fractures in the middle-steeply inclined reservoirs gradually propagated from along the dip direction to perpendicular to the direction. The difference in fracture propagation in up-dip and down-dip direction of steeply inclined reservoirs is mainly due to the difference in fracture pressure caused by stress changes at different burial depths, causing the fractures to first propagate along the dominant channel with low stress.