Researches On Well Killing And Control Rules In Deepwater Drilling

Well killing is a necessary means for well control when a kick was encounteredduring deepwater drilling. There are basically two conventional methods employed toundertake well killing operations, which are the Driller’s Method and theWait-and-Weight Method. Although the principle and procedures of well killing arealmost the same for both the land and deepwater drilling, the control rules of wellkilling in deepwater drilling is rather different from that of well killing in land drillingdue to the different borehole structure and geometry, layout of the BOP and choke lines,gas kick migration behavior along wellbore, environment conditions, etc. This paper hasmade an attempt to systematic study the controlling rules of well killing in deepwaterdrilling and has built a control model which was the most conforms to guide the wellkilling construction accurately and reduce the well control risk.Based on the summary of the well killing process and control rules throughconventional Land Driller’s Method and Wait-and-Weight Method, a control model wasestablished to characteristics of long choke line, temperature distribution of well and gascompressibility. The equations of each moment relevant parameters in well when a kickencountered was formed.In order to find the different control rules, the deepwater well killing model andconventional land well killing model were compared and analyzed, and got the wellkilling in deepwater drilling need more precise and accurate wellhead pressure control,especially for the control of construction time and standpipe pressure. The well killingpressure control in deepwater drilling was more difficult than conventional land drilling.The effect of relevant factors for control and process of well killing in deepwaterdrilling was analyzed. The relationship of each changing parameters used by chart wasdisplayed. The conclusions could be gotten that lower rate of flow, lager inner of chokeline, lower overflow and lower bottom hole pressure were benefit to well pressurecontrol.