Research On Temperature And Pressure Coupling And Downhole Throttling Of Wellbore Under Injection And Production Conditions

The well of high temperature and high pressure of reservoir temperature is higher,and heat exchange occurs between shaft and formation with high temperature energy carried by fluid in production,which causes annular pressure of shaft and affects shaft safety;Different injection parameters have different effects on temperature and annular pressure of shaft during inject of CO₂,and the distribution of temperature and pressure is different after stabilization;Throttle can effectively prevent natural gas water from being distributed and increase production efficiency of gas well.Therefore,the paper mainly studies the injection and production conditions of high temperature and high pressure of gas well and the distribution of temperature and pressure in the process of underground restriction,which provides data reference for the design of shaft structure.The main research contents are as follows:Considering the interaction between fluid physical parameters and shaft temperature and pressure and the coupling effect of temperature and pressure,a shaft temperature prediction model for high temperature and high pressure of gas well is established.The shaft temperature distribution map is obtained,and the influence of production rate,production time and geothermal gradient on shaft temperature is analyzed.Based on typical shaft structure,a shaft temperature and pressure coupling calculation model is established to obtain multi-annular air pressure.Force distribution diagram is used to analyze the influence of production,production time and ground temperature gradient on annulus pressure.By analyzing the variation of physical parameters of CO₂ fluid with temperature and pressure,a prediction model of temperature in CO₂ injection shaft is established.The influence of different injection parameters on shaft temperature and pressure is quantitatively studied by making programs with MATLAB.Mathematical models of temperature and pressure drop are established by studying throttling process mechanism,and the law of temperature and pressure change in throttling wells is analyzed by simulation software.The Studies have shown that the effect of production time on the temperature and pressure of the wellbore is mainly concentrated in the initial stage.The temperature and pressure increase after the production time exceeds 40 days is less than 5%;When the output is between 0 and500,000 cubic meter per day,the increase in the temperature and The pressure of the wellbore is large,and then the production is continued to increase,and the increase in temperature and pressure is less than 3%;the influence of the geothermal gradient on the temperature and pressure is linear.The pressure,time,temperature,and velocity of the injected CO2 will affect the wellbore temperature and pressure.During the downhole throttling process,the temperature and pressure in the throttle are rapidly reduced;the temperature and pressure after throttling are significantly reduced.