Mechanical Analysis Of The Production String In Natural Gas Well

With the rapid development of the global economy and the increasing awareness of environmental protection,the demand for natural gas is increasing day by day.More and more natural gas wells have been put into production.Well temperature and pressure will change after the gas well is put into production.On the one hand,it caused the annular protection liquid to be heated and expand,which resulted in the annulus pressure;On the other hand,it caused the change of the length and the stress of the protuction string,which caused the failure of the column.This seriously affected the safe and stable production of gas wells.Therefore,it is very important to predict the wellbore temperature and pressure distribution accurately,and to understand the annular pressure and the stress of the string.The main contents of this paper are:Based on the theory of fluid mechanics and heat transfer,the temperature and pressure calculation model is established by using mass conservation,energy conservation and momentum theorem;Through the differential iteration,the temperature and pressure coupling calculation program is compiled,and calculated.The calculation results show that the higher the production,the greater the wellbore pressure drop and the higher the wellhead temperature.The annular pressure at home and abroad is analyzed,and the mechanism is analyzed.Based on the effect of thermal expansion and pressure bulging effects,the annulus pressure calculation model was established.The calculation results show that the increase of temperature and pressure is the main cause of the annulus pressure in the production process.The higher the production,the higher the wellhead temperature and the greater the pressure of the annulus.Analyzing the mechanical of the production string in natural gas well,the calculation model of additional axial force and elongation of oil pipe and production casing is established.Combining the temperature and pressure distribution model,the annulus pressure calculation model and the mechanical analysis model of production string,the C# software is used to develop the mechanical analysis software of the natural gas well production string.The calculation and analysis of site example are carried out.