Mechanism Research Of Hydraulic Fracture Interaction In Shale Reservoir

Unconventional energy such as shale gas has became a hot issue in the energy research,the experiment of shale gas in America indicated that hydraulic fractures method is an important means to stimulate shale gas production.It has a great practical significance for the volume fracturing design in unconventional reservoirs to explore the mechanism of hydraulic fracture interaction.In this paper,based on rock fracture mechanics and finite element method,create a fracture propagation model,use simulation to study the interaction between hydraulic fractures and natural fractures.Analysis fracture space,stress difference and unequal space that has impact on the interaction between hydraulic fractures,and research the criterion interaction between hydraulic fractures and natural fractures.Result show that,for homogeneity and isotropic shale reservoir,when the two fractures of horizon well fracturing,they will propagation from each other,as the distance between them gradual become larger,they will form into a "dumbbell" shape.Fracture space and stress difference would inhibit fracture deflection.When there have three fractures in equal space,the middle fracture inhibited by the outer fractures,if the space are not equal,middle fracture would propagation to the farther one.Simultaneously fracture simulation result show that two fractures would turn close to others.It will form a region of stress variation that has benefit on natural fractures cracking and propagation.When hydraulic fractures approach to natural fractures,the form would be interfered by the lateral.That will show various patterns when hydraulic fracture intersect natural fracture,in this paper,we analysis the relationship between intersect angle and critical net pressure in hydraulic fracture,discuss the impact of rock tension and friction factor of natural surface.