Research On Optimum Design Of Perforation Cluster Parameters For Heterogeneous Shale Reservoirs

Compared with the successfully developed shale in Europe and America,Chinese shale has generally experienced more complex geotectonic movements and is characterized by low porosity and low permeability,natural fracture development and strong heterogeneity.When the traditional uniform cluster perforation is used for subsection fracturing,many problems may occur,such as the poor development of the crack and the fluctuation of the numbers of perforated clusters.So the traditional method limited the high efficiency exploration and development of shale gas reservoir.Therefore,it is necessary to research non-uniform cluster perforation optimization methods based on the characteristics of shale in China.In this paper,the heterogeneity of shale reservoir is firstly described.By introducing geochemical parameters and rock mechanics parameters,the shale heterogeneity characteristic equation based on analytic hierarchy process is established.Then the heterogeneity of the shale reservoir along the direction of the wellbore is evaluated and divided.Based on the reservoir heterogeneity description,the fracture model,crack propagation model and induced stress field model are also established.Furthermore considering the change of hole friction and the extension of crack propagation,the model of crack initiation,crack propagation and induced stress field are established respectively.At the same time,Pore parameters and cluster parameters are optimized.Finally,based on the above research results,a non-uniform clustering perforation optimization designing method for heterogeneous shale reservoirs is developed and the calculation software is compiled.The research results in this paper can provide some theoretical and practical guidance for efficient exploration and development of shale.