chapter 13 deviation controlnew

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1、Chapter13THEPROBLEMOFDEVIATIONANDDOGLEGGINGINROTARYBOREHOLESINTRODUCTIONDeviationindrillingoperationsisnotanewproblem.Thediamondcoredrillwasinventedin1865andwidelyusedasacabletooldrillinminingoperations.ThefirstevidenceofconcernaboutholedeviationwastheinventionbyNolteninGermanyin1874of

2、theuseofhydrofluoricacidtoetchandpredictholedeviation.LateraSouthAfricanminernamedMacGeorgeinventedtheclinostattopredictbothdeviationanddirection.Theclinostatconsistingofamagneticneedleandaplumbimmersedingelatinwasloweredintotheholeandthegelatinwasallowedtoset.Theinstrumentwasthenbroug

3、httothesurfaceanddeviationanddirectionwerereaddirectly.AtameetingofminingengineersinLondonin1885MacGeorgepresenteddataillustratingdeviationsof75ftin100footmineshafts.ThePetroleumIndustrydidnotbecomeawareoftheproblemuntiltheSeminole,Oklahoma,boomofthemiddle1920's.Townlotspacingwasthepri

4、maryfactorcontributingtotheexperienceoftheindustry.Thereareactualrecordedincidentsofoffsetwellsdrillingintoeachother,drillingwellsdrillingintoproducingwells,tworigsdrillingthesamehole,andthewellsinthegeometriccenterofthestructurecominginlowormissingthefieldcompletely.Itwascommondrillin

5、gpracticeatthattimetouseonlylargedrillpipewithnodrillcollarsandallavailableweightsinceweightindicatorswerenotavailable.Engineersandtheindustryingeneralmadeaconcentratedefforttosolvethecrookedholeproblem.Asaresult,mostofthepracticescommonlyusedtodayinanefforttocorrectandcontroldeviation

6、wereconceived,experimentedwithandadoptedinthe1920's,50yearsago.Themosteffectivepracticesadoptedandstillusedtodayweretheuseofdrillcollarsforweightandrigidity,theuseofstabilizersatvariouspointsinthestringtocontroldeviationandproviderigidity,andthepracticeoffanningbottomtoreduceangle.Thef

7、irsttwohavemadetheindustrymillionsofdollars;thepracticeoffanningbottomhascosttheindustrymillionsofdollars.Forwhateverreason,earlyresearchersweresuccessfulintheirefforts.WellssurveyedinthegreaterSeminole,OklahomaareawithandwithoutstraightholepracticesproducedtheresultsinTable13-1.Thed