Computational Study On Wellbore Pressure And Killing Engineering In Deep Water Wells

The ocean contains rich oil and gas resources, according to the forecast, deep sea areas have the best future growth prospects in China’s oil and gas areas. If gas kick happens during deep water drilling, the gas in annular will rise along the annulus and choke line, which will results in blowout. Thus it is necessary to do some research on the wellbore pressure and well control parametersBased on the conventional well killing methods and the particularity of the deepwater condition, this paper describes phenomenon of heat transfer between the annulus and formation, and establishes the model of wellbore temperature prediction. Considering the effect of long choke line, this paper simulated the well-killing process of driller’s method and engineer’s method and the pressure change rules during well-killing. The author programmed the deep water wellbore pressure and well-killing calculation software. The software can calculate the temperature field, annulus pressure field and well-killing parameters. With the software, this paper conducts sample calculation on X well of the South China Sea. First of all, during normal drilling process, this paper calculated the wellbore temperature field and the annulus temperature field. And this paper gained the temperature curve, and the effects of different factors on temperature field. Then in the process of gas kick, this paper calculated the annulus pressure field and gas-liquid two-phase flow parameters in the annular and get gas-liquid two-phase annular flow curves. Finally, during the well-killing process, respectively, for deepwater engineer’s method and deepwater driller’s method, this paper calculated the well-killing parameters, and got the casing pressure and riser pressure curves change rules, and studied the relevant parameters on the well killing effect of pressures in the process.Considering the specific circumstance of deepwater well-killing, this paper calculated the wellbore pressure and well-killing parameters such as fluid density, well-killing time of engineer’s method and driller’s method. And we can see how the casing pressure and riser pressure change during the process of well-killing.After the comparison of two methods, we come to the conclusion that if gas kick happens and it is possible to get well-killing fluid in a short time, the engineer’s method is better.