Low Permeability Reservoir Development And Fracturing Of Numerical Reservoir Simulation Study

This study of numerical simulation for reservoir developed by fracturing is mainly used on reservoir performance prediction of pre-frac and post-frac . It can provide the basis for the comparison of different fracturing projects. It is the kernel parts of optimizing fracturing projects for developing.To simulate the pre-frac and post-frac performance of low permeable reservoir , the technology studying and developing is needed,and this will do good for improving economically developing low permeable reservoir,it is significant in theory and practice.On the study of numerical simulation for reservoir developed by fracturing,the simulator of consider dual-porosity reservoir, non-Darcy-flow in reservoir and fracture , permeability changed with the effective porosity pressure, arbitrary fracture azimuth , fracture conductivity change in the fracture with the time is a really problem urge to solve. There is not any paper published on this so far.Based on the conventional dual-porosity simulation model, a new non-linear combined-flow-rule model for fluid flow, has been used in this paper by introducing the large-opening fractures with arbitrary azimuths and non-Darcy-flow rule. This model can describe not only the linear Darcy's flow phenomena but also the nonlinear flow cases including low-velocity-flow in low permeability media and high-velocity-flow in high permeability media.In the model of this paper, the fluids flow in large-opening fractures are described by the high-velocity non- Darcy -flow rule, and the influences of start-up pressure to fluids flow in low permeability media are represented by low-velocity non-Darcy-flow rule, while the linear-flow phenomena are characterized by the Darcy rule.Considering the variation of rock permeability with time is one of the important works of this paper. The practice and experiments show that the changes of the reservoir pressure could result in the variation of the permeability in the reservoir. In addition, the pressure of reservoir would vary with the different development time, thus the permeability of the reservoir would change with the development time. This phenomenon is called time-difference-effect in this paper.A detailed discussion is given in this paper about the variation of conductivity of large-opening fracture with time, and a measure is raised to settle this problem.The function of characterizing large-opening fractures with arbitrary orientation is another feature of this simulator. By this function, the simulator could simulateconveniently the influences, exerted by the man-made fractures with arbitrary azimuth, to the dynamics of fractured wells or reservoirs.This simulator can be used in simulating the multi-fracture or symmetry fracture cases, it can be used in post-frac performance prediction of single well fracture , refracture and systematic fracture.Tests and applications of the research achievements are important contents of this paper. Examples given in the paper have verified respectively the effects of all the methods and functions which have been presented.