石油钻采工艺2026，Vol.48Issue(4)：465-474,10.DOI:10.13639/j.odpt.202601022
低压地层定向钻井井漏环空失返后MWD无信号原因分析
Results interpretation of MWD signal dropout after total lost circulation in directional drilling in low-pressure formations
摘要
Abstract
A systematic investigation on the causes of MWD signal dropout after total lost circulation in directional drilling in low-pressure formations has yet to be fully established.Wherefore,based on the U-tube principle of drilling fluid circulation,a model was established to calculate pump pressure,flow resistance inside and outside the drillstring,and annular fluid level height under conditions of total lost circulation.A case study of a certain well in Tongchu was conducted here.The annular fluid level height was calculated from changes in pump pressures.The variation patterns of pump pressure and annular fluid level with respect to circulation rate,density,viscosity,and downhole tool flow resistance were analyzed qualitatively and quantitatively.The pressure distribution w ithin the drillstring and gas release conditions were also determined.Results indicate that after total lost circulation,the drop in annular fluid level creates a suction effect,reducing the hydrostatic pressure of the fluid column in the water eyes of the upper MWD drillstring section.This leads to a low-pressure zone approaching to zero pump pressure,sometimes even negative pressure zone,inducing dissolved gases release and producing gas columns that block the transmission of MWD drilling fluid pulse signals.This is the fundamental reason why MWD signals cannot be detected at the surface.Measures such as increasing circulation rate and viscosity,re-injecting fluid into the annulus,reducing bit nozzle diameter,or replacing turbine tools are proposed to increase internal drillstring pressure,thereby reducing the likelihood of gas column formation and improving MWD signal transmission stability.These findings provide theoretical support and practical guidance for restoring MWD signals after total lost circulation in low-pressure formations drilling operation.关键词
MWD/低压地层/定向钻井/环空失返/U型管模型/泵压/环空液面Key words
MWD/low-pressure formation/directional drilling/total lost circulation/U-tube model/pump pressure/annular fluid level分类
能源科技引用本文复制引用
侯学军,侯伟煌,姜玉峰,冯煜,申浩,姜宏,邓桥..低压地层定向钻井井漏环空失返后MWD无信号原因分析[J].石油钻采工艺,2026,48(4):465-474,10.基金项目
国家自然科学基金"智能连续油管钻井电动钻具多参数耦合力学驱动与自动控制机理研究"(编号:52274004) （编号:52274004）
重庆市自然科学基金创新发展联合基金重点项目"智能连续油管钻井电动钻具多参数振动耦合力学行为机制研究"(编号:CSTB2023NSCQ-LZX0132). （编号:CSTB2023NSCQ-LZX0132）
