Shale Gas Reservoir Modelling And Numerical Simulation Study

Since reservoir characteristics of shale gas reservoirs are low porosity and super-low permeability,development strategy of most wells depends on hydraulic fracturing and then connection with nature fractures.The performance of wells usually goes through a peak gas production in the early years,no matter produced through vertical wells or horizontal well,where most of recoverable reserve produced in these years before production rate plunged.Shale gas production decline rate is much higher than conventional gas reservoir’s in the initial phase.However,when the shale gas production is stable,they tend to decline slowly,that is,shale gas reservoirs have longer period of pressure spreading and production circle than conventional ones.Thus,it is important to quantify these conundrums during shale gas development through reservoir modelling and numerical simulation techniques.To development these theories,based on research of shale gas reservoir modelling and numerical simulation,three-step modelling approach is adopt in this paper.Firstly,static model is conducted combined integrated study of static and dynamic data;secondly,analyze sensitivity of parameters in shale gas development;moreover,shale gas reservoir model is calibrated by history matching;these tested approaches provide a useful reference on infill drilling,hydraulic stimulation,and secondary fracturing.Major research results are as follows:(1)According to the seismic characteristics of the shale gas reservoir,re-define the faults and interpret seismic horizons.When picking the faults,a new workflow about shale gas faults identification is proposed.Time-depth conversion is completed.A fine structure model built through the combination of horizontal well geo-steering data and a reliable stratigraphic framework of the model.(2)Study the stochastic modelling method.The approaches of "Three-step modelling",combination of deterministic modelling and stochastic modelling are purposed in the paper.Statistical research on reservoir modeling parameters performed,and variogram is calculated by seismic inversion,based on which properties model of base reservoir and properties model under facies control are established.(3)Study parameters of rock brittleness:Young’s modulus,Poisson’s ratio,and brittleness index,as well as the X-plot.The shale reservoir with favourable brittle is predicted in the study area.(4)The DFN model is established.The combination of "Ant-Track" and deterministic method obtain the large size fractures model The mid-size fractures model is achieved by K-max attribute and stochastic method.FMI and K-max attribute use to established small-scale fracture model(5)Through the combination of reservoir model and numerical simulation,a workflow to study natural fracture aperture is conducted.The natural fracture aperture is researched in the study region.(6)Upscaled the reservoir model and processed the shale gas reservoir parameters,considered the hydraulic stimulation and completion design,the dynamic reservoir model is established.The author analyzed various sensitivity parameters in typical shale gas development and the main factors of the shale gas development are determined.(7)Achieved a calibration of the reservoir model,completed history matching and forecast.