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ROD PUMPING DEVIATED WELLS

ROD PUMPING DEVIATED WELLS. Jun Xu, Ken Nolen, Dennis Shipp, Andy Cordova, Sam Gibbs Lufkin Automation April 20, 2005. CONTENTS. Deviated Well Model What Is the Key Factors in Deviated Well Design? rod buckling rod guide and sinker bar side/drag load dog leg severity

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ROD PUMPING DEVIATED WELLS

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  1. ROD PUMPING DEVIATED WELLS Jun Xu, Ken Nolen, Dennis Shipp, Andy Cordova, Sam Gibbs Lufkin Automation April 20, 2005

  2. CONTENTS • Deviated Well Model • What Is the Key Factors in Deviated Well Design? • rod buckling • rod guide and sinker bar • side/drag load • dog leg severity • How to Design a Deviated Well? • Case 1 – Rod Pumping Design in a Deviated Well • Case 2 – Optimized Wellbore Path

  3. Deviated Well Model • Generalized 3-D Wave Equation Model (by S. Gibbs, in 1992) • vertical and deviated wells • consideration of 3-D wellbore path • consideration of side load/drag load and viscous friction • rod guide design • optimized well bore path design • SROD and DIAG

  4. x(north) y(east) r(s) ds qn mg Ff t1 F z (down) SCHEMATIC OF ROD ELEMENT IN DEVIATED WELL FORCES ON ROD ELEMENT

  5. SROD Mathematical Modeling Foundation

  6. Key Factors in Deviated Well Design • side/drag loads • dog leg severity • rod buckling • rod guide and sinker bar • well bore path • rod pumping feasibility • overloaded rod, gear box or motor • design and optimization with whole system

  7. Tubing Tubing Tubing guide guide ¾” rod 25’ ¾”rrrod guide guide Q Q Q F F F guide Drag Friction (F), Side Load (Q) bare rod friction coefficient =0.2 ratio of guide friction to bare rod friction =1.5 Q =18 lbs/rod Q = 19 lbs/rod Q = 19 lbs/rod F= 0.2X18 = 3.6 lbs/rod F = 0.2X1.5X19 = 5.7 lbs/rod F =0.2X1.5X19 = 5.7

  8. Dogleg Severity • Dogleg severity, º/100 ft, – curvature of wellbore • Dogleg severity is not directly used in calculation c A

  9. Control Drag Loads • smaller pump size • pump depth • using rod guides • design sinker bar • tubing rotation • optimized wellbore design

  10. Rod Buckling • Harmful consequences • tubing wear/leaks • rod parts • Root causes • downhole friction • faster pumping • pump-off condition • under-balanced units • unit geometry selections • any combinations Rod Buckling Downstroke Upstroke Casing Tubing Rod String Fluid Level Pump

  11. Buckling Tendency • What is buckling tendency? • buoyancy ≠ buckling • true load ≠ buckling tendency • buckling tendency • Buckling criteria: • buckling tendency ≥ Pcr

  12. Euler Loads and Measured Buckling LoadsFrom Scott W. Long, SPE 35214

  13. How to Control Rod Buckling ? • Some most practical and effective ways • good pump fillage • smaller pump • slower speed • add sinker bar • rod guide design • selecting proper pumping unit and balance the unit • optimized wellbore design

  14. Wellbore Deviation Data • Input well deviation survey • inclination • azimuth • SRPD designed wellbore • true vertical depth • horizontal departure • kick-off depth • build rate (º/100 ft) • drop rate(º/100 ft) • well bore type

  15. Example 1 of Deviated Well Design

  16. System Performance for Existing Design pump depth : 11076’ pump diameter : 1 1/2” stroke length : 216” speed : 5.48 spm rod : 3080’ (1”) (M) 2980’ (7/8”) (M) 4410’ (3/4”) (M) 600’ (7/8”) (M) 103% 115% 196 bpd 92% 112%

  17. System Performance for Improved Design pump depth : 11076’ pump diameter : 1.25” stroke length : 216” speed : 6.83 spm rod : 3080’ (1”) (W) 2980’ (7/8”) (M) 4410’ (3/4”) (M) 600’ (7/6”) (M) 92% 98% 219 bpd 83% 78%

  18. Rod Buckling 6.8 SPM Pump-off (80%) 6.8 SPM Pump-off (80%) 6.8 SPM Full Pump

  19. Example 2 of Deviated Well Design

  20. Problems for Existing Well pump depth : 6300’ tubing pump : 2 – 1/4” tubing size “ 2 -7/8” (below KOP) stroke length : 192” speed : 9.1 spm 86 rod design : 2310’ (1”) 2400’ (7/8”) 1590’ (3/4”) (16 M.G.) 85% 100% 822 bpd 92% 114%

  21. Proposed Modifications pump depth : 6300’ insert pump : 2 1/4” tubing size : 3 -1/2” (anchored 5000’) stroke length : 168” rod : 1800’ (1 -1/8” N-97) 2800’ (1” N-97) 400’ (1-5/8” grade C) 1300’ (7/8”) (N-97) 91% 80% 808 bpd 74% 86%

  22. Rod Buckling and Drag Load

  23. Optimized Wellbore Design Buildup-hold (KOP=5100’) Buildup-hold (KOP=2000’) Buildup-hold-drop (KOP=2000’)

  24. Optimized Wellbore Design

  25. Optimized Wellbore Design

  26. CONCLUSIONS • An accurate and comprehensive predictive program is the only one tool for deviated well design and simulation. • Several options can be chosen to control rod buckling, that is, good pump fillage, smaller pump, slower speed, sinker bar, rod guides, and proper pumping unit. • Smaller bore pump can be effective used to reduce side/drag load. • Optimal wellbore paths exists that will reduce side/drag load, power cost and equipment loads and on-going R&M costs.

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