Study On Optimization Of Development Mode In Shale Gas Well Factory

Compared with conventional oil and gas reservoirs,shale gas has its special characteristics,such as : accumulation,storage,seepage and so on,and the exploitation of shale gas is obviously different with conventional reservoirs.At present,the technology of shale gas in North America has been relatively mature,speeding up the process of exploitation of shale gas greatly.However,because of insufficient understanding of shale gas percolation mechanism and imperfect production technology in China,the technology of shale gas production is still infancy,which greatly affects the economic and efficient development.The theory of non-linear seepage of shale gas is the basis of development of shale gas reservoir.In this paper,the characteristics of adsorption,desorption and diffusion of shale gas in the process of reservoir formation and migration are studied.The mathematical model and numerical model of gas-water two-phase seepage in shale gas reservoir are established,and the productivity formulas of different percolation stages in shale gas well factory development mode are derived.At the same time,combining with the numerical simulation software,the development mode of well factory is simulated,and the gas reservoir parameters and engineering parameters which affect the development effect of well factory are analyzed.Finally,the order of the influence of sensitive parameters on the cumulative gas production of shale gas reservoir is judged by orthogonal experiment method in order to provide reference for the efficient development of unconventional shale gas in China.The main achievements of this paper are as follows:Based on the investigation of shale gas literature at home and abroad,the geological characteristics of shale reservoir,the mechanism of fluid storage,the rule of fluid flow and the flow pattern are deeply studied,which builds a foundation for the establishment of shale gas reservoir model.Based on the study of fluid flow in shale gas reservoir,a gas-water two-phase mathematical model of shale gas reservoir is established.In matrix,the model considers the adsorption of Langmuir,the first diffusion law of Fick,the effect of rock compression;in fractures,the seepage flow of the fluid conforms to Darcy seepage law.At the same time,the numerical model of shale gas reservoir is established by using the fully implicit difference method for the mathematical model.In different seepage stages of shale gas,the productivity rules of single crack cluster,inter-crack interference,crack tip interference and fracture-end interference are deduced and studied respectively.The parameters which influence the synchronous fracturing development effect of shale gas well factory are further understood.Combined with numerical simulation software,the development mode of shale gas well factory is simulated.The effects of Langmuir pressure,Langmuir volume,fracture conductivity,production pressure,horizontal well length and other parameters on well factory development are studied.Finally,the influence weight of sensitive parameters on accumulated production of shale gas is analyzed by orthogonal experiment.