Study On Numerical Simulation Of Unsaturated Seepage Based On Water-gas Two-phase Flow Theory And Its Application

The research of unsaturated seepage system is important for science and engineering research in porous medium, especial in study on dynamics of groundwater, it has the prominent function for the zone of unsaturated ,which is contact the groundwater and the underground water system. The unsaturated seepage research develop from the one phase flow to two phase flow and multi-phase flow become more and more complicate as the development of research of unsaturated zone. It has important meaning for the saturate-unsaturated two phase flow study in raining in rock soil engineering and hydraulic engineering.Based on the research theory and experiment of two phase flow of water and gas in the soil gas and store field, this text deduce the differential equation of two phase of water and gas and deduce the mathematics model and the solution of two phase of water - gas . IMPES method is usually used previously , which deal with the pressured implicitly and the saturation explicitly, its convergence speed is slower and it doesn't used in complicated numerical simulated calculation. With the advance of complexity of geological calculation and the accretion of span of time and space, IMPES method become outdated .this paper put forward a new method ,which convergence speed is fast and precision is high to the coupling model of two-phase flow of water and gas-fully-implicit simultaneous solution, in which the pressure and saturation are solved implicitly. This method overcome the numerical dispersion in IMPES method , so the solution is stable positively.Based on the mathematics theory above all and the seepage theory in raining, Some aspects for saturate-unsaturated two phase flow study during raining in model constitution , methods innovation are discussed detailedly in this paper. The seepage mathematics model of saturate-unsaturated two phase seepage flow of water and gas is developed detailedly, which is soluted by finite difference method and fully-implicit simultaneous solution. We can draw conclution from the results of caculated example that using two phase seepage flow theory to research the calculate-uncalculated seepage in raining show the change of the soil seepage field and accretion theory.According to the mathematics theory of two phase flow and the theory of coalbed methane migration and production , the coupling model of two phase of gas water of coalbed methane migration and production is founded. And then the model is applied to the Qinshui basin. Using the ejection data of water and gas and observation curve of water level of TL007 well-net, history matching of gas and production is calculated and the primary parameters which affect the production of coalbed methane are rectifed an identified . This model is applied to the prediction of production potentiality of gas and water of TL007 well-net by different things ,the result is well.