| With the rapid development of economy and people’s material living standards, the demand of human for natural gas and oil continue to increase in the recent years. There are abundant storage and extensive distribution in low permeability reservoirs. The low permeability reservoirs will be the main fossil resources to be developed for a considerably long period of time. So it has profound significance to study on low permeability reservoirs development for the sustainable development of petroleum industry. The low permeability reservoirs differ in terms of theory of fluid flow in porous medium, microscopic flow mechanism, flow characteristics and development pattern compared with moderate and high permeability reservoirs. The main difference is that there exists nonlinear seepage. Based on such theoretical knowledge as fluid mechanics in porous medium, reservoir engineering, modern mathematics and computer programming, the flash black oil mathematical model was established assuming that stock-tank liquid component and gas component can exist in both liquid phase and gas phase under reservoir conditions. Beginning with the law of nonlinear seepage of low permeability reservoirs, the flash black oil mathematical was extended with the consideration of the character of nonlinear seepage in low permeability reservoirs. A set of theory and methods of flash black oil simulator with the consideration of the character of nonlinear seepage in low permeability reservoirs was established. Through this research in the dissertation, main results are obtained as follows:(1)Assuming that stock-tank liquid component and gas component can exist in both liquid phase and gas phase under reservoir conditions, the flash black oil mathematical model which includes the basic assumptions, mathematical equations, the initial conditions and boundary conditions was established. The flash black oil mathematical was extended with the consideration of the character of nonlinear seepage in low permeability reservoirs. The pseudo start pressure gradient model and nonlinear seepage model considering the influence of nonlinear section of nonlinear seepage curve were established.(2)According to differential equation discretization method, the mathematical model was discretized with finite difference method and corresponding numerical model was obtained. After the linearization processing of numerical model the coefficient matrix and matrix element were obtained and the linear equations were solved.(3)The method to solve the oil saturation and gas saturation was proposed considering that stock-tank liquid component and gas component can exist in both liquid phase and gas phase under reservoir conditions. The approach of passing bubble point and passing dew point was derived. The well processing method was proposed.(4) Based on modern software engineering the numerical simulator was developed with Fortran95programming language with the modularization design.(5)The simulation results comparison between the simulator and general commercial reservoir simulator were used in ideal models of low permeability reservoir and gas condensate reservoir.The results verify the correctness of simulator. (6)The simulator was used to simulate the ideal model of low permeability reservoir. The results comparison between the Darcy model, pseudo start pressure gradient model and nonlinear seepage model were studied on the effect of the development indexes and the distribution of pressure and saturation.(7)The simulator was applied in Y123well region. The history matching and the research on reasonable well pattern were completed and the well adjustment plan was determined.The developed simulator is independent intellectual property rights. The pseudo start pressure gradient model and nonlinear seepage model with the consideration of the character of nonlinear seepage in low permeability reservoirs were integrated with conventional Darcy mode in simulator to lay the foundation for the engineering applications of simulator. |
PDF Full Text Request