Pressure And Rate Transient Analysis Of Fractured Horizontal Wells In Shale Gas Reservoirs

The combination of horizontal drilling and multistage hydraulic fracturing technology has been proved to be the most effective method to develop shale gas reservoirs.It can not only create high-conductivity flow paths,but also activate and connect existing natural fractures to form large fracture networks.Firstly,we develop two approaches that are aimed at investigating the effects of stimulated reservoir volume(SRV)based on the microseismic measurements.We respectively establish circle and elliptical composite reservoir model where inner region and outer region are both regarded as dual porosity media to take into account the effect of SRV.Secondly,we present a new semi-analytical model to study the pressure behavior and production performance of fractured horizontal wells with finite conductivity fractures in shale gas reservoirs.Multiple migration mechanisms are considered,which contain diffusion in kerogen bulk,desorption from the surface of organic matters and clay minerals,slippage flow in matrix pores,transient-state inter-porosity flow and Darcy flow in natural fractures.Finite-conductivity hydraulic fractures,stress sensitivity effect and inclination angles are also taken into account.Thirdly,we propose a semi-analytical model to simulate complex fracture networks in shale gas reservoirs with considering multiple transport mechanisms.We analyze the effects of secondary fractures on the pressure behavior and compare the orthogonal fracture networks with the un-orthogonal one to investigate the effect of the geometry of fracture networks.Fourthly,we present an efficient model to study the varying-width or nonplanar fractures which are generated during hydraulic fracture propagation.This approach can serve as an efficient tool to evaluate well productivity and provide critical insights into shale gas reservoirs development.Lastly,we employ embedded discrete fracture model(EDFM)to simulate fracture networks in shale gas reservoirs.Considering the huge quantity and distribution uncertainty of natural fractures in shale formation,we establish a hybrid model incorporating dual porosity model(DPM)and EDFM.A transient-state DPM is used to describe shale matrix and natural fracture system and EDFM is employed to characterize hydraulic fractures.The effects of natural fracture system on the production performance of shale gas reservoirs are investigated.