简介：Deepwatersedimentsarepronetolosscirculationindrillingduetoalowoverburdengradient.Howtopredictthemagnitudeofleak-offpressuremoreaccuratelyisanimportantissueintheprotectionofdrillingsafetyandthereductionofdrillingcostindeepwater.Startingfromthemechanicalpropertiesofashallowformationandbasedonthebasictheoryofrock-soilmechanics,thestressdistributionaroundaboreholewasanalyzed.Itwasfoundthattherockorsoilonaboreholeisintheplasticyieldstatebeforetheeffectivetensilestressisgenerated,andtheeffectivetangentialandverticalstressesincreaseasthedrillingfluiddensityincreases;thus,tensilefailurewillnotoccurontheboreholewall.Basedontheresultsofstresscalculation,twomechanismsandleak-offpressurepredictionmodelsforshallowsedimentsindeepwaterdrillingwereputforward,andthecalculatedvaluesofthesemodelswerecomparedwiththemeasuredvalueofshallowleak-offpressureinactualdrilling.TheresultsshowthattheMHPS(minimumhorizontalprinciplestress)modelandtheFIF(fracturinginformation)modelcanpredictthelowerandupperlimitsofleak-offpressure.ThePLC(permeablelostcirculation)modelcancomprehensivelyanalyzethefactorsinfluencingpermeableleakageandprovideatheoreticalbasisforleak-offpreventionandpluggingindeepwaterdrilling.

简介：Decreasingtherisksandgeohazardsassociatedwithdrillingengineeringinhigh-temperaturehigh-pressure(HTHP)geologicsettingsbeginswiththeimplementationofpre-drillingpredictiontechniques(PPTs).ToimprovetheaccuracyofgeopressurepredictioninHTHPhydrocarbonreservoirsoffshoreHainanIsland,wemadeacomprehensivesummaryofcurrentPPTstoidentifyexistingproblemsandchallengesbyanalyzingtheglobaldistributionofHTHPhydrocarbonreservoirs,theresearchstatusofPPTs,andthegeologicsettinganditsHTHPformationmechanism.OurresearchresultsindicatethattheHTHPformationmechanisminthestudyareaiscausedbymultiplefactors,includingrapidloading,diapirintrusions,hydrocarbongeneration,andthethermalexpansionofporefluids.Duetothismulti-factorinteraction,acloudofHTHPhydrocarbonreservoirshasdevelopedintheYing-QiongBasin,butonlytraditionalPPTshavebeenimplemented,basedontheassumptionofconditionsthatdonotconformtotheactualgeologicenvironment,e.g.,Bellotti’slawandEaton’slaw.Inthispaper,wefocusontheseissues,identifysomechallengesandsolutions,andcallforfurtherPPTresearchtoaddressthedrawbacksofpreviousworksandmeetthechallengesassociatedwiththedeepwatertechnologygap.Inthisway,wehopetocontributetotheimprovedaccuracyofgeopressurepredictionpriortodrillingandprovidesupportforfutureHTHPdrillingoffshoreHainanIsland.