关键词:

"> 砂泥岩互层, 层理面, 垂向应力, 地层倾角, 相互作用, 水力压裂

Abstract:

Hydraulic fracturing is one of the main technologies to realize the efficient development of shale gas，and bedding plane is the key factor affecting the distribution of the three-dimensional geometry of hydraulic fractures. At present，scholars at home and abroad have explored the impact of shale reservoir bedding on the vertical propagation of hydraulic fractures，but there is less understanding on the vertical propagation pattern of hydraulic fractures in sand-shale interbedded reservoirs. Based on the theory of linear elastic fracture mechanics，a multi-bedding hydraulic fracture propagation model of coupled stress - damage - filtration loss is established in this study，and the impacts of change in reservoir stress field，formation dip angle and tensile strength of bedding plane on the vertical propagation of hydraulic fractures are analyzed. Compared with the microseismic monitoring results，accuracy of the model can reach more than 95%. The simulation results show that propagation of hydraulic fracture can be divided into three stages in the process of penetrating through the bedding plane of sand-shale interbedding，and the propagation direction of hydraulic fracture in the third stage is determined by the change in reservoir stress field，formation dip angle and tensile strength of bedding plane. Reservoirs with low stress difference and low dip angle are favorable to the opening of bedding plane，while reservoirs with high stress difference and high dip angle are favorable to the vertical propagation of hydraulic fracture. As the tensile strength of bedding plane decreases，the opening degree of bedding plane increases. This is mainly because that the lower the tensile strength of bedding plane is，the less the energy consumption for opening the bedding plane is.

Key words:

"> sand-shale interbedding, bedding plane, vertical stress, formation dip angle, interaction, hydraulic fracturing