Research On Fracture Initiation And Propagation Among Multi-Cluster Fracturing In Horizontal Well

Multi-cluster fracturing technology of horizontal well is the most advanced fracturing process.The crack initiation and expansion of the section is the key to the effect of fracturing.It is important to study the law of the initiation and expansion of multi-cluster fracturing fractures in horizontal wells.In this paper,the Chang 8 reservoir in Honghe area is taken as the object of study,and the rock mechanics characteristics of Chang 8 reservoir are analyzed by logging data,which lays the foundation for numerical simulation.Considering the fluid-solid coupling effect of porous media,the finite element model of fracture initiation of horizontal well fracturing is established according to the stress distribution and tensile strength criterion of perforating horizontal well.The crack initiation pressure is obtained by numerical simulation.In the actual well calculation,the error rate of the verification model is 6.6%,which is reasonable.On the basis of this,the effects of reservoir elastic modulus,horizontal principal stress difference,perforating parameters and azimuth angle of horizontal wellbore on initiation pressure were studied.Based on the cohesive bond unit,the finite element model of horizontal well fracturing with single-layer fracturing expansion considering the effect of fluid-solid coupling is established by preset cohesive fracture unit.The effects of elastic modulus,Poisson 's ratio,fracturing fluid viscosity and construction displacement on single-cluster fracture propagation were analyzed.On this basis,the multi-cluster crack propagation model is established,and the propagation law of cracks under different perforation spacing and cluster number is studied.The results show that the reasonable cluster spacing and cluster number are helpful to reduce the inter-slot interference and improve the fracturing effect.In this paper,the finite element method is used to explore the initiation and propagation of fractures in low permeability sandstone reservoirs,which provides a theoretical support for the production and transformation of low permeability reservoirs.