Research On Early Warning Of Fluid Accumulation In Gas Wells Based On Flow Pattern Conversion

In the process of gas well exploitation,the formation energy is gradually reduced,which leads to the gradual decline of the liquid carrying capacity of gas well,and finally the phenomenon of liquid loading will occur,or even production halt.Liquid loading will greatly increase the production cost of gas wells and seriously affect economic benefits.Therefore,it is very necessary for gas well production to forewarn the generation of liquid in time and analyze the risk degree of gas well production.Experts and scholars at home and abroad have carried out long-term research on the calculation of critical gas velocity,and put forward different calculation methods of critical gas velocity.However,different methods have their application scope,so it is necessary to compare and modify the existing model.In this paper,the transition of flow pattern is used as the early-warning judgment of effusion.For the high gas-liquid ratio,the annular flow agitation flow is used as the judgment basis for liquid loading;for the low gas-liquid ratio,the slug flow agitation flow is used as the judgment basis for liquid loading.This paper analyzes the principle of fluid accumulation in gas wells and the changes of liquid film and liquid drop during the flow pattern conversion,and clarifies the relationship between the flow pattern conversion and liquid loading.Finally,the calculation method of critical gas velocity of gas well is determined,and based on this calculation method,the forewarning program of liquid loading is compiled.By running the program,the influences of well angle,liquid production,gas production,temperature pressure and wellbore inner diameter on critical gas velocity of gas well are analyzed.This paper takes the influence of liquid drop as the main factor,combined with the data of liquid loading in the field,and uses the software model to calculate and analyze.It is found that the common location of liquid loading is the well section with the wellhead,the bottom of the well,and the well section with the sharp change of the well angle.The calculation method of critical gas velocity and the forewarning program of gas well liquid loading based on this method are of certain guiding significance for timely warning the situation of liquid loading in wellbore and guiding the use of drainage gas production measures.