Alternative drilling

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1、FM5-484/NAVFACP-1065/AFMAN32-1072PartThree.SpecialConsiderationsChapter9AlternativeWellConstruction9-1.Fundamentals.Underspecialconditions,methodsotherthantherotaryanddown-holehammermaybemoreexpedientforwelldrilling.Conditionsfavoringlessstandardmethodsinclu

2、dethefollowing:Availabilityoflocal,nonstandarddrillingequipmentandqualifiedpersonnel.Ashallowaquiferthatcanbedevelopedquicklywithoutmobilizationdelays.Availabilityofunskilledpersonnelonly.Requirementsforasmallwatersupply.9-2.JettedWells.Inthejettingmethod,yo

3、udigaboreholeusingahighvelocitystreamofwater.Thestreamloosensthesoilandwashesthefineparticlesupandoutoftheborehole.Thejettingmethodisparticularlysuccessfulinsandysoilswhenthewatertableisclosetothesurface.Jettingissimpleanddependable,andyouusehandtoolsrathert

4、hanbulkydrillingequipment.Twojettingproceduresareavailablewashinginacasingorsinkingaself-jettingwellpoint.Withthejettingmethod,youcansamplethegeneralcharacterofaformationbyexaminingthecuttingsbroughttothesurfaceinthereturnflow.a.Equipment.(1)Swivel.Thewaters

5、wivelmustbeabletocarrytheweightofthedrillpipeandmustsustainthemaximumpressuredeliveredbythepump.Figure9-1showsaconnectionthatyoumayuseatthetopofsmall-diameterjettingpipesinplaceofaswivel.(2)DriveWeight.Thisisweightyoudroponthepipetohelppenetrateclayeyorsemif

6、irmsoil.(3)JettingFluid.Wateriscommonlyusedinjetting,butafluidwithgreaterviscosityandweightmaybepreparedwithclayorcommercialbentonite.However,aheavierfluidtendstosealtheboreholewall,preventingwaterpenetration.Inthejettingprocess,fluidisledfromtheboreholetoap

7、itwherecuttingssettletothebottom.Thejettingpumpthenrecirculatesthisfluid.UndercertainconditionsintheArctic,steamisusedtoconstructjettedwells.9-1FM5-484/NAVFACP-1065/AFMAN32-1072(4)Hoist.Youneedahoisttohandlethedrillpipeandcasing.Youmayusehand-operatedequipme

8、ntsuchasatripodwithtackle.Ifavailable,youshoulduseapercussion-typedrillingrigwithapowerhoist(Figure9-2).(5)Pump.Apumpwithsuitablehoseconnectionabletodeliver50to100GPMat50psiisadequate.Thequantit