Enhancement of the Economics and Safety of PMCD Operations
Enhancement of the Economics and Safety of PMCD Operations
Enhancement of the Economics and Safety of PMCD Operations
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Managed Pressure DrillingApplication Answers<strong>Enhancement</strong> <strong>of</strong> <strong>the</strong> <strong>Economics</strong> <strong>and</strong><strong>Safety</strong> <strong>of</strong> <strong>PMCD</strong> <strong>Operations</strong>ChallengePressurized mud-cap drilling (<strong>PMCD</strong>), one <strong>of</strong> a number <strong>of</strong> discrete variants <strong>of</strong> managed pressure drilling(MPD), allows drilling to continue during conditions <strong>of</strong> severe or total fluid losses in highly depleted orcavernous formations. A characteristic <strong>of</strong> this technique is <strong>the</strong> need to kill <strong>the</strong> well before pulling <strong>the</strong>bottomhole assembly (BHA) out <strong>of</strong> <strong>the</strong> hole, <strong>of</strong>ten a lengthy <strong>and</strong> expensive process, especially if severaltrips are required. The challenge is to provide a means <strong>of</strong> tripping pipe without <strong>the</strong> need to kill <strong>the</strong> well,<strong>the</strong>reby improving both <strong>the</strong> safety <strong>and</strong> <strong>the</strong> economic aspects <strong>of</strong> <strong>the</strong> operation.Use <strong>of</strong> <strong>the</strong> downhole deployment valve (DDV ® ) tooleliminates <strong>the</strong> need for killing <strong>the</strong> well to make trips <strong>and</strong>allows safe <strong>and</strong> efficient installation <strong>of</strong> anirregularly shaped BHA.ConstraintsWhen drilling wells using <strong>PMCD</strong> techniques, inmany cases wells which had been undrillableuntil <strong>the</strong> advent <strong>of</strong> this technology, severalconsiderations must be examined:• While losses <strong>of</strong> sacrificial drilling fluids (typicallywater or sea water) are understood, <strong>the</strong> loss <strong>of</strong><strong>the</strong> annular viscous mud cap will occur whentripping pipe <strong>and</strong> this occurrence can be anextreme economic disadvantage.• A rotating control device (RCD) is required toseal around <strong>the</strong> tubular to allow fluid injectionunder pressure.• Adequate sources <strong>of</strong>well control fluids mustbe maintained. During<strong>of</strong>fshore operations, <strong>the</strong>sacrificial fluid is normally seawater, but water supplies in onshoreoperations may be inadequate, resulting inexcessive fluid costs.• The need to kill <strong>the</strong> well prior to pulling pipeshould be eliminated in order to improve <strong>the</strong>economics <strong>of</strong> <strong>the</strong> process.• The need for snubbing operations must beeliminated, if possible, to improve personnel<strong>and</strong> operational safety, as well as to optimizeoverall economics.© 2008-2010 Wea<strong>the</strong>rford. All rights reserved.
Managed Pressure DrillingFeatures, Advantages <strong>and</strong> Benefits• The DDV ® tool performs <strong>the</strong> function <strong>of</strong>a downhole lubricator, enabling <strong>the</strong> safeinstallation <strong>of</strong> long <strong>and</strong> complex assemblies into,<strong>and</strong> retrieval from, <strong>the</strong> well.• Using <strong>the</strong> DDV tool saves <strong>the</strong> time requiredto kill <strong>the</strong> well <strong>and</strong> maintains <strong>the</strong> well duringtripping. This improvement trims operational time<strong>and</strong> reduces <strong>the</strong> use <strong>of</strong> kill fluid, benefiting welleconomics.• When tripping out <strong>of</strong> <strong>the</strong> hole, <strong>the</strong> pipe is pulledwith stripping techniques while using an RCD toa point above <strong>the</strong> DDV tool, but below <strong>the</strong> pipelight point. The valve is <strong>the</strong>n closed <strong>and</strong> testedby bleeding <strong>of</strong>f above <strong>the</strong> valve. The surfacepressure is brought to zero <strong>and</strong> <strong>the</strong> pipe trippedat conventional rates under fully safe operatingconditions.• When running in <strong>the</strong> hole with an irregularlyshaped BHA, <strong>the</strong> BHA is tripped normally to <strong>the</strong>DDV tool depth. The mud cap is reestablished,as needed, <strong>and</strong> <strong>the</strong> casing pressured to equalizeacross <strong>the</strong> valve. The valve is <strong>the</strong>n opened <strong>and</strong><strong>the</strong> BHA run to bottom in “pipe heavy” conditionswhile using st<strong>and</strong>ard stripping techniques.• Thus, both tripping out <strong>of</strong> <strong>and</strong> into <strong>the</strong> hole ismuch faster <strong>and</strong> safer with resultant economicimprovements.• BHAs <strong>and</strong> tubular materials are h<strong>and</strong>led atsurface with conventional techniques, enhancingboth personnel <strong>and</strong> operational safety.• Running or pulling <strong>of</strong> <strong>the</strong> pipe below <strong>the</strong> DDVtool is done in “pipe heavy” conditions, <strong>the</strong>rebyallowing all such operations to be performed withconventional stripping methods—<strong>the</strong> need forsnubbing is eliminated.• By eliminating <strong>the</strong> need for killing operations <strong>and</strong>pumping well control fluids to allow pipe tripping,a beneficial economic impact can be made interms <strong>of</strong> reducing fluid costs <strong>and</strong> <strong>the</strong> expense<strong>of</strong> maintenance on <strong>the</strong> pumping equipmentnormally associated with <strong>PMCD</strong> operations.Operational Outline• Install <strong>the</strong> DDV tool as an integral part <strong>of</strong> <strong>the</strong>casing, setting immediately above <strong>the</strong> problemzones, <strong>and</strong> cement in place with st<strong>and</strong>ardmethods.• Run cleanout string; drill out cement <strong>and</strong> floatshoe.• Leave <strong>the</strong> DDV tool in <strong>the</strong> open position <strong>and</strong> drillahead until <strong>the</strong> need for <strong>PMCD</strong> is established.• Establish <strong>PMCD</strong> conditions <strong>and</strong> drill ahead untila trip out <strong>of</strong> <strong>the</strong> hole is needed.• Using st<strong>and</strong>ard stripping methods, pull <strong>the</strong> BHAto a point above <strong>the</strong> DDV tool.• Close <strong>the</strong> DDV tool by applying pressure to<strong>the</strong> closing line <strong>and</strong> <strong>the</strong>n test <strong>the</strong> DDV tool bybleeding <strong>of</strong>f above it.• Bleed <strong>of</strong>f surface pressure <strong>and</strong> trip <strong>the</strong> drill stringat st<strong>and</strong>ard trip speeds.• Change <strong>the</strong> BHA, as necessary, <strong>and</strong> run innormally to a point directly above <strong>the</strong> DDV tool.• Establish mud cap, as needed, <strong>and</strong> pressure up<strong>the</strong> casing <strong>and</strong> pipe to equalize across <strong>the</strong> DDVtool, <strong>and</strong> <strong>the</strong>n pump through it.• Apply pressure to <strong>the</strong> opening line to open <strong>the</strong>DDV tool; run <strong>the</strong> BHA to bottom <strong>and</strong> continueoperations.3© 2008-2010 Wea<strong>the</strong>rford. All rights reserved.
Managed Pressure DrillingSecure Drilling SM services: <strong>of</strong>fering an alternative to conventional drilling methodswhen drilling hazards, formation damage <strong>and</strong> speed are <strong>of</strong> particular concern.Our Secure Drilling services incorporate several drilling techniques—including air,managed pressure <strong>and</strong> underbalanced drilling—<strong>and</strong> associated technologies tooptimize drilling performance, minimize formation damage <strong>and</strong> mitigate hazards.The no-snub, no-kill answer.wea<strong>the</strong>rford.comWea<strong>the</strong>rford products <strong>and</strong> services are subject to <strong>the</strong> Company’s st<strong>and</strong>ard terms <strong>and</strong> conditions, available on requestor at wea<strong>the</strong>rford.com. For more information contact an authorized Wea<strong>the</strong>rford representative. Unless notedo<strong>the</strong>rwise, trademarks <strong>and</strong> service marks herein are <strong>the</strong> property <strong>of</strong> Wea<strong>the</strong>rford. Specifications are subject to changewithout notice. Wea<strong>the</strong>rford sells its products <strong>and</strong> services in accordance with <strong>the</strong> terms <strong>and</strong> conditions set forth in <strong>the</strong>applicable contract between Wea<strong>the</strong>rford <strong>and</strong> <strong>the</strong> client.© 2008-2010 Wea<strong>the</strong>rford. All rights reserved. 5807.01