Study On The Characteristics Of Nonlinear Seepage Flow In Shale Reservoirs

As an important part of unconventional resource system,Shale oil has become a hot spot of oil and gas exploration and development in recent years.Shale reservoir belongs to the tight reservoir with low porosity and low permeability.Shale reservoir has complex micro-structure and seepage mechanism,leading to having lower natural productivity or nothing than conventional rasource.Moreover,it usually requires horizontal well mining and reservoir reformation to get industrial oil flow.Therefore,it is of great theoretical and practical significance to deeply study the percolation theory of horizontal wells and fracturing horizontal wells in shale reservoirs,analyze the influencing factors of reservoir development and transformation for analyzing the production performance of oil well and exploiting the shale reservoir efficiently.On the premise of studying shale reservoir development technology and relevant theory at home and abroad,this paper takes the shale reservoir nonlinear seepage characteristics as the research object,based on the shale reservoir characteristics and reservoir percolation mechanism,establishing horizontal well and fracturing horizontal well percolation mathematical model considering start-up pressure gradient,stress-sensitive effect and combined action of both,according to the theory of percolation mechanics of reservoir.Solving the mathematical model by using reservoir engineering principle and the method of mathematical physics such as Laplace transform,Duhamel principle,Bessel functions and so on,and getting the expressions of the constant production pression solution and constant pressure yield solution from different models.According to the results,drawing the pressure dynamic curve and production decline curve.Based on the curve,the horizontal well flow process can be divided into six stages,and the horizontal flow process of fracturing can be divided into eight stages.And then analyzing the factors affecting the flow law and production performance of shale reservoir.Using the actual production data of the mine,combined with the established horizontal well mathematical model and fracturing horizontal well mathematical model of shale reservoir,and analysising the pressure and production decline to verify the accuracy of the established model.