Iteration Method For Solving The Integral Gas Fluid Equation

Well test method is widely used to detecting gas reservoir nowadays. By means of changing the working system of gas well and testing parameters such as output, pressure, temperature and so on to analyze the character of gas layer, well testing draw the conclusion on the different development law of gas reservoir.According to elastic unstable fluid flow theory, based on observed data of bottomhole pressure, under some mathematical treatment, Data processing of well testing gets gas layer parameters of drainage area and makes the characteristic informtion of geology, all of these will be important to the gas exploration and development. But due to the compressibility of gas significantly higher than fluid, the state equation of gas is different from fluid. Otherwise, the viscosity of gas changes with the pressure greatly, and it can't be approximate treatment as constant in fluid flow, so it is necessary to look for a simple high efficient numerical method in engineering. The relative literature directly apply the initial pressure to the integral calculation, but it can just get the solution of the first level approximation.Based on data processing of well testing in gas reservoir detecting, focus on the relationship between partial equation and integral equation, the partial differential equation is transformed into corresponding integral equation, by means of one cycle of iteration after direct computation, the second approximate solution is abtained and it is proved to be feasible in theory. Finally, we draw the conclusion that after computation of iteration it can get higher accuracy of gas reservoir detecting. The numerical examples show the effectiveness of this method and provides a new available method to data processing of well testing of well testing.