Investigation Into The Production Numerical Simulation On Shale Gas Reservoir With Volume Fracturing

Shale gas is the unconventional and clean natural gas that is found trapped within mud shale formations,which is of significant development potential.The abundant shale gas resource in China is strategically meaningful to the nation,which lacks conventional oil and gas resources and yet has great energy demands.At present,despite the flourish of on-site experience and technologies in shale gas development,numerous challenges still exist in both theory and practice.Great uncertainty exists in multi-scale flow mechanism due to the low permeability and complex pore-throat distribution.The knowledge of the hydraulic fracture propagation principle is not sufficient yet.The detailed characterization of the irregular fracture geometry and fluid flow features in production prediction numeric simulation models still lack efficient approaches.Therefore,it is of great significance to further the numeric simulation study on shale gas horizontal well with volume fracturing.Firstly,in-depth analyses of the shale formation physical properties and fracture flow characteristics are conducted by tests of permeability,pore structure,methane adsorption and fracture conductivity.Such tests can provide the basic parameters for subsequent production numerical simulation study.Secondly,based on the continuum model,using facies-controlled modeling method as reference,the paper characterizes complex hydraulic fracture network constrained by mechanical mechanism or mico-seismic monitoring results,and discrete fracture network modeling method is applied to further describe the subdivided fracture conductivity.The study compares different ways to deal with the hydraulic fracture in production numerical simulation,it shows the advantage of complex fracture model.Then,the paper systematicly analyzes fators which have great influence on shale gas production based on the improved fracture characterizing method,directly investigates the influence of reservoir factors and treatment factors(stress difference,natural fracture angles and cluster spacing)on gas well production,which is a new perspective to integrate the fracture propggation and productivity analysis.Last but not the least,dual-medium discrete fracture network model for shale gas horizontal wells with volumetric fracturing is constructed by applying finite element method.The model takes into account the effect of gas desorption,Knudsen diffusion,transition flow,slip flow,Darcy flow mechanism and the decline of fracture conductivity.The advantage of the descrete fracture model is that applying the dimensionality reduction method to deal with the fracture system,which can realize modeling arbitrary geometry fracture,and orthogonal fracture network,oblique fracture network and fractal tree fracture network are used to reveal the advantage of finite element method.This paper mainly performed numeric simulation studies on shale gas productivity.Facies-controlled modeling technique is firstly applied to integrate complex fracture network propagation with productivity simulation.This paper also explores the application of finite element method to the characterization of complex fracture network and to the shale gas productivity simulation.The result of this paper provides significant insights to efficient shale well stimulation and development.