Research On Pipe Flow In The Wellbore And Seepage In The Reservoir Coupling With Heat Flow

In the exploration and exploitation of petroleum, many parameters such as oil and gas reserves, permeability in the reservoir and wellbore damage, can be known through the inversion of instant pressure at bottom hole of the well. Since temperature has much in common with pressure, research of interpretation and inversion on instant temperature at bottom hole and research on the influence and correction of temperature on pressure well test are launched in this paper. Thus, the temperature data is effectively used and deficiency of pressure well test is made up. The correct prediction of temperature profile in well bore is the important basis of oil-gas well design and dynamic analysis, it also has directive significance in many aspects of oil gas field.In this paper, the varing temperature of wellbore and formation in injection well or producing well with time is researched. The formation consists of many layers, which have different thermodynamics properties. The whole system consists of wellbore zone, thermal skin zone and formation zone. In the formation there is only horizontal thermal exchange with vertical thermal exchange ignored. In the wellbore there is only heat convection with heat conduction ignored. Wellbore and formation are connected by Ramey heat-transfer coefficient. Laplace transform is used to solve the equations, after inversion, an analytical solution of temperature in wellbore and formation is obtained and further, typical temperature well testing curves are obtained. Then the measured temperature data can be used to fit the typical temperature well testing curves. Now the measured temperature data can be qualitatively interpretated and some thermal parameters of formation can be obtained.Because steam injection changes the temperature of reservoir, so the properties of fluid in reservoir and shape of pressure curves in reservoir is changed. A pressure test model and curve fitting method in steam injection well is presented. A multi-area radial composite reservoirs model is used to classify strata. Laplace transform is used to get the analytical solution. In this paper, the correction of pressure by temperature is realized through gas equation of state. After the pressure is corrected, typical pressure well testing curves are obtained. the measured pressure data can be used to fit the typical pressure well testing curves. Some actual examples are given here and corresponding interpretation results are also given.Considering that gas temperature has obvious influence on pressure, a pressure model with thermal effect considered in gas well is established here, which gives the governing equations for pipe flow in wellbore and seepage equations of the real gas in reservoir. In seepage equation pseudo-pressure is imported,and according to boundry conditions and initial conditions, a half-analytic and half-numerical expression of bottomhole pressure of variable-flowrate gas well is obtained through superposition principle, which is the pressure boundry condition for pipe flow in wellbore.The Bottomhole pressure varies with time and producing state,and it's connected to reservoir. So pipe flow in wellbore and seepage in reservoir must be coupled,and solved iteratively. PISO(Pressure Implicit with Splitting of Operators) method is used to solve wellbore governing equations. By solving wellbore governing equations bottomhole flowrate is obtained,which is the input parameter for seepage equations in reservoir. The iteration must keep running to achieve convergence. Then distribution of temperature and pressure is obtained. The result of calculation shows that thermal effect has great influence on the early shape of the pressure well-test curve, which gives a explaination of exceptional behavior of measured pressure data in early period and will not only enrich modern welltest theory but also give a better understanding of reservoir.