In Gaoshiti-Moxi structure,central Sichuan Basin,most strata from the Jurassic Ziliujing Formation to the Triassic Xujiahe Formation are strongly permeable.And drilling practice demonstrates that rapid formation of mud cake with false thickness certainly creates difficulties,for example frequent pipe sticking,long reaming segment,and time-consuming complexity treatment.So,both causes and countermeasures were analyzed for the sticking in several wells.Then,through innovations on the design of micro-reaming tool,optimization of drilling parameters and drilling-fluid performance,and development of anti-sticking technology,some novel an-ti-sticking reaming while drilling(RWD)tools were set up.Results show that(i)with a creative eccentric-type stabilizer,an eccentric micro reamer while drilling is independently developed,which may expand caliper in sticking segments with effect;(ii)to innovate the matched bending screw,to optimize bottomhole assembly(BHA)and drilling parameters,and to intensify safety measures are condu-cive to minimizing risks in sticking;and(iii)to enhance fluid performance and to control water loss are profit for alleviating the rapid formation of mud cake with false thickness in the highly permeable strata.In addition,consisting of bending screw equipped with the stabilizer+stabilizer+eccentric micro reamer,the anti-sticking RWD tools are created and applied to three wells in this structure.Ob-vious consequence has been achieved in caliper expansion or sticking prevention,resulting in the average time in anti-sticking reaming decreased by 93%per well.And the success application is referential for fast drilling in sticking segments.
Gaoshiti-Moxi structureJurassicHigh permeabilityPipe stickingComplexity control
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