The Study Of Macro Numerical Reservoir Simulation Based Micro Seepage Mechanism During High Water Cut Development Period

After analyzing different scale reservoir development methods, the paper indicates that study based on micro seepage mechanism and macro reservoir simulation should be used to calculate liquid distributing features during high water-cut development period. By studying micro seepage mechanism of water and oil, the paper shows that the relative permeability curve measured in reservoir physics lab by steady or unsteady method is a macro statistical regularity, which doesn't allow for the influence of micro rock features on liquid flow rules, so the relative permeability curve measured in reservoir physics lab is not applicable to describing water and oil distribution in reservoir during high water-cut development period. At the same time, the paper indicates some questions of classical reservoir simulation, finds out reasons that result in those questions.Pore-level network model can be used to calculate the relative permeability curve based on micro throat and hole features and if it could be combined with classical reservoir simulation technique, the macro reservoir numerical simulation method based on micro seepage mechanism will be accessible. According to percolation theory and pore-level network model, the calculating formulae of accessible fraction, critical percolation value, effective fraction and phase equivalent conductivity in different wet systems and displacement processes are derived in dissertation. Substituting prismatic tube with equilateral triangle section for ancient tube with circular section is favorable for describing rock wetting characteristics and calculating micro liquid distributing features. The relative permeability curves are worked out by Bethe network model, at the same time the influence of micro characteristics on curves are analyzed. The analyzing results prove the method feasible.The 1D reservoir developing method with starting pressure is put forward, which enlarges applicable range and which analyzes the influence of gravity, capillary, starting pressure on reservoir performance parameters. . The three -dimension and three -phasemathematical model of water, oil and gas are established, which takes micro seepage mechanism into account. The difference method is used to get numerical equations, the equations are solved by conjugating pretreatment grads orthomin method, at the same time the influences of grid refinement and dead node elimination on coefficient matrix are discussed, the methods to calculating development indexes are put forward. According to the solving method, the computer program is compiled and completed.Compared with classical reservoir simulation, the most important advantage of macro reservoir simulation based on micro seepage mechanism is that the oil and water relative permeability changes because of different micro throat and hole distribution features in reservoir are taken into account. By this improvement, the distributing rules and form of remaining oil in reservoir pore can be described clearly. It become a reality that black oil mathematical model could provide decision making explanations for profile controlling, water plugging, chemical flooding and other enhanced oil recovery(EOR) methods. In addition, the model has other merits, for example, adopting different relative permeability curves in different formation, the new way to refine grid and to eliminate dead node, dealing with the changes of permeability and oil viscosity in different development period. The following parameters can be gained through analyzing simulation result: sweep efficiency, remaining oil reserves abundance, recoverable reserves abundance, controlling reserves by single well, recoverable controlling reserves by single well, water-flooded area, and so on. At last, the model is tested by one reservoir block in Sheng-Li petroliferous area, the different relative permeability curves in different parts of reservoir are worked out by network model and the method to deal with permeability is discussed. The results are analyzed, the merits mentioned are also tested. The analyzing resu...