Research On The Numerical Simulation Of Gas-well Flow Field With Underground Nozzle

Underground restriction with natural gas is a new research direction in exploitation craft of natural gas. Underground restriction isa craft technique of gas exloitation in order to depress wellhead pressure.control output and cancel ground calefaction attemperature.It is that the nozzle is put on an appropriate location in wellbore in order to depress pressure and avoid hydrated compound at the same time by making use of terrestrial heat which makes more current temperature after throttle than original temperature of hydrated compound formation.Gas-well flow field was numerically simulated with underground nozzle and without underground nozzle. On the base of reasonably predigesting relevant physical model, the group of equation of pressure, temperature, flux and density about well was educed by the conversation of mass, momentum and energy and logical mathematical model is set up. Without underground nozzle, we received the result for well flow field by using 4th-order Runge-Kutta iteration method, and with nozzle by using Newton iteration method. To some gas-wells which are given origi n-nal and boundary condition, we compute the program which is made by the Fortran language so that the distribution of correlative parameters of gas in wellbore are found out with well depth, and contrast the practical date with the computed results, then analyzed the difference between them in order to find out the flow rules in well. By the results, we validated the usability of this simulator and its important significance to research underground throttle.Making use of the above mathematical model, numerical value method and homologous calculation procedures, we can get the distributionof correlative parameters of fluid in wellbore, including the distributionat nozzle.But these parameters distribution is one dimensional with well depth. At nozzle where section is very various, laminar flow turn int-o turbulent flow, velocity change subsonic one into supersonic one, and Shockwave occurs at the same time, the flow state is very complicated. This complicated fluxion must be described with two dimensions or three dimensions. Here,by using CFD software (Fluent), we can simulate t-he state of fluid at nozzle and obtain the distribution of correlative parameters of fliud and some else characters. Because of the axisymmetric cylinder, we only simulate 2D state.