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Coil Tubing Drilling (CTD) Kuparuk Field, North Slope, Alaska

Coil Tubing Drilling (CTD) Kuparuk Field, North Slope, Alaska. 2012 US Canada Research Forum Dan Venhaus. What is CTD?. 2” drill “pipe” on a continuous spool Drill with surface pressure Internal electric line to “talk” to drilling tools and directional control

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Coil Tubing Drilling (CTD) Kuparuk Field, North Slope, Alaska

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  1. Coil Tubing Drilling (CTD) Kuparuk Field, North Slope, Alaska 2012 US Canada Research Forum Dan Venhaus

  2. What is CTD? • 2” drill “pipe” on a continuous spool • Drill with surface pressure • Internal electric line to “talk” to drilling tools and directional control • Use existing 3-1/2” wellbore to drill horizontal sidetracks • Small design - few logging tools available • Flexible • Higher doglegs, tighter turns • Less “push” 5°/100’ dogleg 45°/100’ dogleg

  3. CTD Drilling Rig Rig Module Mud Module Mud Pits Mud Pumps Power Pack

  4. D C B A 2 miles Kuparuk BackgroundField Development • 6 Billion STBOOIP • 2 main reservoir sands • A & C • Differing permeability • Commingled production • Direct N/S line drive development • 160 acre well spacing • ~1:1 producer/injector ratio

  5. KWS Top Kuparuk Time Structure KRU 3D North Kuparuk BackgroundFaulting & Structural Complexity • Structure • SE-plunging anticline with 1000’ of relief • Single OWC on east flank • Significant reservoir faulting • Faulting more pervasive than imagined at discovery and early development • Controls reservoir compartmentalization • Fault Behavior = • Primary Uncertainty ~5 miles

  6. Kuparuk CTD Evolution 2006: Slimhole resistivity April 2011: 165 CTD laterals 206,773’ drilled Aug. 2004:1st lined multi-lat 1998: CTD BHAs downsized 2009: Ribsteer 1998 2011 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2005:1st quad-lat; KWS 3D seismic Jan. 2010: WK 3D survey 1998-2004: single-laterals May 2009: Dedicated, purpose-built rig

  7. CTD Liner Flow-by Whipstock Slotted Liner Kuparuk CTD Evolution • What we used to drill… • Single lateral • Single window • Simple completions Production Tubing

  8. Kuparuk CTD Evolution 8 horizontal laterals 12900’ of total hole drilled and cased Chemical tracer installed to monitor flow

  9. Increase pressure/ fluid compressibility 1000’ Challenges and SolutionsHigh differential pressure • Challenge: Compartmentalized fault blocks with high differential pressures • Solution(s): • Managed pressure drilling • Shut in and back flow wells Fault-bounded amplitude 5035psi 4672psi 1052psi 1220psi 4221psi 5310psi Initial reservoir pressure = 3200 psi

  10. 2000’ Challenges and SolutionsLimited length • Challenge: lateral length limited to ~3000’ • Solution(s): • Agitator • Ribsteer vs. bent motor • Well design and planning • Result: • Recently completed 4200’ horizontal lateral (World record 2” coiled tubing) motor ribsteer

  11. Summary • Highly developed technique for challenged oil • Requires existing wellbores & infrastructure • Niche tool to develop small pockets of oil • Technology has come a long way but……. • Alaska development over a 20-year period • Significant investment in people & technology • Dedicated team of 18 engineers & geoscientists support rig • Technology only used in Alaska  small R&D market for vendors • The Challenges: • 2012 Per Well cost ~7.5 mm$ (60% increase since 2009 start) • Older wells & aging infrastructure • Maintaining production results • Oil rates typically in 100’s of barrels per day per well

  12. Questions?

  13. Target TypesStandoff fromswept area 13000’MD 12000’MD 11000’MD “parent” well log OWC 6550’ ~1200’ standoff from parent drilled in non-pay portion of reservoir Pay Watercut of parent: 90% Watercut post-CTD sidetrack: 50%

  14. 1500’ Target TypesAdd length to increase rate Sealing fault Throw: ~60-90’ N

  15. Challenges and SolutionsUnstable shale • Challenge: Geosteering in complex reservoir with unstable interbedded shale • Solution(s): • Managed pressure drilling • Well design to avoid shale intervals • Expedient plugbacks Base permafrost D C B A

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