Reserch For Effect Mechanisms Of Flooding On The Empty Gas Well Killing

In recent years,the problem of well control in drilling process is becoming more complicated for the continuous expansion,development of deep,ultra-deep wells and complex strata.In the drilling process of gas wells,after drilling fluid ejection,bare eye segment is too long,there are no drilling tools or clogging in the situation also occurs,at this time well killing is known as empty well killing.In the air well killing,due to the conventional circulation channel is destroyed,can not use the general well killing means,for this kind of complex well killing work,at present,the selection of displacement method is often considered,and in the replacement method,in order to save the time and the cost,the predecessors proposed a dynamic displacement method pressure well.The main problem of dynamic displacement method is how to avoid the bad working conditions caused by the occurrence of liquid in the gas carrying liquid and the well killing liquid to the wellhead.At present,no research has clearly pointed out the specific factors of flooding,and there is no concrete analysis of the influence mechanism of flooding on air well killing.Based on the mechanism of flooding formation,the conclusion of flooding correlation experiment and the basic principle of dynamic displacement method,the viscosity,surface tension,droplet diameter,well angle,diameter of drill pipe joint and the eccentric distance of drill pipe are included in the calculation,and a new mathematical model suitable for dynamic displacement method is established.A set of calculation software based on engineering calculation function and analysis and calculation function is compiled by Matlab2017aGUI,and the calculation is carried out by using the drill pipe in the well and the drilling pipe in the well(the pipe is clogged in the well and difficult to unblock).The effects of 10 factors,such as liquid dynamic viscosity,liquid surface tension,gas density in well,pressure fluid density,casing inner diameter,drill pipe outer diameter,casing pressure,well angle,outer diameter of drill pipe joint and drill pipe eccentricity,on the displacement and gas displacement of well killing in the process of well killing are analyzed.Through the analysis and study of the influencing factors of flooding,the following conclusions are drawn.Liquid dynamic viscosity,gas density,casing pressure,well angle,diameter of drill pipe,outer diameter of drill pipe joint and eccentric distance of drill pipe promote the occurrence of the flooding;Liquid surface tension,fluid density and casing inner diameter have hindered the occurrence of flooding.