Application of Fine Pressure-controlled Drilling Technology to Tarim Gasfield

So far,more and more complicated problems may often occur during drilling some deeper and complex formations,including well kick,lost circulation,toxic-gas leakage,sticking and too long trip time.So,this paper presents the working principles of fine pressure-controlled drilling technology and some relevant facilities at first;and then sums up some features including capturing bottomhole pressure,realizing an automatic control of wellhead pressure and a continue cycle,and controlling accuracy by pressure;thirdly illustrates its application to many horizontal wells for Ordovician carbonate reservoir in central Tarim area;at last draws some conclusions that this technology can (1) solve such downhole accidents as well kick and lost circulation under a narrow pressure window,(2) reduce drilling cost,and (3) realize overbalanced drilling,nearbalanced drilling and underbalanced drilling.