Study On Dynamic Characteristics Of Horizontal Well Pressure In Multi - Stage Fracturing Of Shale Gas Reservoir

In recent years, the multi-stage fractured horizontal well technology has been widely applied in the shale gas reservoir development. Meanwhile the seepage mechanism is more and more regarded by scholars.At present,seepage theory of multi-stage fractured horizontal well is not systematic in shale gas reservoir.Few models consider synthetically the adsorption-desorption,diffusion and Darcy flow, especially linear flow model.The object of this paper is to study the desorption-diffusion-seepage problem in shale gas reservoir.With the combination of modern fluid mechnics in porous medium,well test analysis,reservoir engineering,mathematics method,computer programming and other subjects knowledge,we establish well test model of trilinear flow and five-linear flow for fractured horizontal wells in shale gas reservoirs.lt provides a theorrtical basis for the development of shale gas though studying the dynamic pressure of these model.The main works in this paper are as follows:(1)Based on the reseach of domestic and foreign literature, reservoir characteristics of shale gas are understood and its output and migration mechanism are summarizes.(2)The differential equations of conventional trilinear and five-linear flow model are derived, which provides basic theory for trilinear and five-linear model of shale gas reservoir.(3)The well test model of trilinear flow and five-linear flow is established about multi-stage fractured horizontal wells in single media shale gas.Type curves are plotted and the different flow regimes are identified.The factors of type curves,such as adsorption-desorption coefficient,apparent permeability coefficient,fracture and reservoir conductivity,fracture spacing,transmissibility factor,are analysed. The difference between trilinear and five-linear flow model is seen by contrasting figure.(4)The well test models of trilinear flow and five-linear flow is established about multi-stage fractured horizontal wells in dual media shale gas,which include dual media fracture seepage-matrix steady/unsteady diffusion model and dual media fracture seepage-matix steady/unsteady seepage diffusion. model. Type curves are plotted and the different flow regimes are identified.The factors of type curves.such as storativty ratio,interporosity flow coefficient,adsorption-desorption coefficient, fracture spacing,the length of reservoir, are analysed. The difference between trilinear and five-linear flow model is seen by contrasting figure.(5)The real well test data are interpreted by well test models of shale reservoirs which are established in this paper. The results verify the applicability of the theory model.