Research And Application Of Whole-Process Underbalanced Drilling Through Adoption Of Down-Hole Isolation Method

As an advanced reservoir protection technology, Underbalanced drilling technique hasmade a deep effect on application,and promoted gradually. On present techcicalconditions,snubbing, logging and running in completion tube are overbalance when inunderbalanced drilling,which kill the effct.So the conception"whole- processunderbalanced drilling"was mentioned in china, its core technology is no-killingoperation.The main contents are as follows: underbalanced drilling, no-killing strippingunder pressure,no-killing coring under pressure, no-killing logging under pressure, nokillingrunning in completion tube under pressure.It can be realized by two methods: snubbing and down-hole isolation.This papercontrasts and analysises two methods,and determines to reasearch and application ofDetermining overall scheme of the project,researching process of the technology,fieldtesting in two wells,completing development of downhole isolation system.This paperdiscusses as follows:conceptions advanges,conditions,extents,methods,details and so on,itis a favorable foundation for this techniqueï¼›To analyze and calculate the depth ofDDV,and give two formulas,to analyze no-killing pressure concrol principle and thetechnical measures of no-killing operations and"whole- process underbalanced drilling",Compile the rules of techniqueï¼›To analyze the log under pressure technique,to develop thewellhead setup between two unitsï¼›To analyze and research downhole isolation systemwith independent intellectual property,completing the two whole-process underbalanceddrilling field testing, Forming the technology of whole-process underbalanced drilling by the adoption of down-hole isolation method,to pratice and inspect the technique from fieletesting.