Beam Pumping Workshop Houston Texas October 4 7
Beam Pumping Workshop Houston, Texas October 4 - 7, 2005 Long & Slow vs. Short & Fast Norman W. Hein, Jr. , P. E. – President & Managing Director Oil & Gas Optimization Specialists, Ltd. (OGOS), Midland, TX.
Let’s Vote How should pumping units be operated? • Long & Slow? • Short & Fast? Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 2
Is There a Preference? YES! Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 3
Content • Speed Background – Acceleration Factor – Theoretical Max Speed • Pumping Unit Rating – API Spec – Lufkin Recommendation • Gear Box • Pumping Unit • Fatigue Effects • Well Design Examples Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 4
Speed Background Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 5
Speed Background (con’t) • Acceleration Factor C = (S * N 2)/70, 500 • Don’t exceed free fall speed of the rods • 1962 W. H. Ritterbusch “Petroleum Production Handbook” – “Always choose a speed below that maximum practical limit permitted by free-rod fall so that the polished-rod clamp and hangar bar will not separate on the downstroke. ” – Recommended permissible speed of 70% of maximum free fall limit. Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 6
Speed Background (con’t) • 1965 Bethlehem Steel published “Pumping Unit Selection Charts” – “Normally at speeds which exceed 0. 7 of the free fall velocity, the polished rod begins to leave the carrier. ” • Lufkin in 1984 -85 catalog supported 0. 7 of free fall speed (for Conventional Unit geometries) – 10% reduction if Air Balance – 20% reduction if Mark II • If well straight and pumping fresh water, C = 0. 417 – But seldom is well straight – Typically pumping other than fresh water Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 7
SPM vs. S S (in. ) SPM @70% SPM @C=0. 3 Velocity PR (fpm) 16 42. 9 36. 4 97 24 35 29. 7 119 30 31. 3 26. 6 133 36 28. 6 24. 2 145 42 26. 5 22. 7 157 48 24. 7 21 168 54 23. 3 19. 8 178 64 21. 4 18. 2 194 74 19. 9 16. 9 208 86 18. 5 15. 7 225 100 17. 1 14. 5 242 120 15. 7 13. 3 266 144 14. 3 12. 1 291 168 13. 2 11. 2 315 192 12. 4 10. 5 336 216 11. 7 9. 9 356 240 11. 1 9. 4 376 300 Oct. 4 - 7, 2005 9. 9 8. 4 2005 Beam Pumping Workshop - ©OGOS 420 8
Speed Background (con’t) • Gipson & Swaim recommended for design: 0. 225 < C < 0. 3 (Shallow wells) • > 0. 225 optimize equipment (not too large) • < 0. 3 to stay less than free fall speed N/No’ <0. 35 (Deeper wells) • Gipson & Swaim has always recommended designing PU based on middle stroke for unit. • In real world operating situation, the free fall speed of the rods and the gear box capacity determine maximum pumping speed. Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 9
Pumping Unit Rating • API Spec 11 E “Pumping Units” covers – Gear Reducer (Box) – Unit Structure • Gear Reducer performance based on AGMA Standard 422. 02 • Originally based on 20 SPM for all gear reducers • IN 1981, API revised reducer rating for 456 & larger units Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 10
Pumping Unit Rating (con’t) API larger unit speed rating: Peak Torque Rating (in-lbs) 456, 000 Oct. 4 - 7, 2005 SPM 16 640, 000 16 912, 000 15 1, 280, 000 14 1, 824, 000 13 2, 560, 000 11 2005 Beam Pumping Workshop - ©OGOS 11
Pumping Unit Rating (con’t) • Lufkin Hi-Q Herringbone Gear Speed Reducers – Double Reduction Units – Assume operation ~1150 rpm prime mover – ~30 to 1 ratio D 40 25. 1 D 320 252 D 57 40. 4 D 456 353 D 80 55. 8 D 640 432 D 114 87. 3 D 912 441 D 160 115 D 1280 590 D 228 160 D 1824 853 D 2560 1456 *assumes prime mover speed of 870 rpm Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 12
Pumping Unit Rating w/Structure Pumping Unit Size C 912 -365 (305)-168 C 640 -365 (305)-168 C 456 -305 -168 C 912 -427 -144 C 320 -256 -144 C 640 -305 -120 C 228 -213 -120 C 456 -256 -100 C 160 -173 -100 C 320 -246 -86 C 114 -119 -86 C 320 -246 -74 C 114 -143 -74 Oct. 4 - 7, 2005 Max. SPM 13. 2 14. 3 15. 7 17. 1 18. 5 19. 9 PU Size C 160 -173 -64 C 80 -119 -64 C 114 -173 -54 C 57 -76 -54 C 80 -133 -48 C 40 -76 -48 C 57 -89 -42 C 40 -89 -36 C 25 -56 -36 C 25 -67 -30 C 25 -53 -30 2005 Beam Pumping Workshop - ©OGOS Max. SPM 21. 4 23. 3 24. 7 26. 5 28. 6 31. 3 13
Pumping Unit Rating w/Structure Pumping Unit Size Max. SPM PU Size Max. SPM M 1824 -427 -216 9. 3 M 320 -305 -100 13. 7 M 912 -365 -216 9. 3 M 228 -173 -100 13. 7 M 1280 -427 -192 9. 9 M 228 -246 -86 14. 8 M 456 -305 -192 9. 9 M 114 -143 -86 14. 8 M 912 -427 -168 10. 6 M 228 -200 -74 15. 9 M 456 -305 -168 10. 6 M 114 -173 -74 15. 9 M 912 -365 -144 11. 4 M 114 -173 -64 17. 1 M 320 -256 -144 11. 4 M 114 -143 -64 17. 1 M 456 -365 -120 12. 5 M 228 -213 -120 12. 5 Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 14
Pumping Unit Rating w/Structure Pumping Unit Size Max. SPM PU Size Max. SPM A 2560 -470 -240 10. 0 A 912 -427 -144 12. 9 A 912 -470 -240 10. 0 A 456 -305 -144 12. 9 A 1824 -427 -216 10. 5 A 640 -365 -120 14. 1 A 912 -427 -216 10. 5 A 320 -256 -120 14. 1 A 1824 -427 -192 11. 1 A 320 -305 -100 15. 4 A 912 -427 -192 11. 1 A 228 -173 -100 15. 4 A 1280 -305 -168 11. 9 A 160 -200 -74 17. 9 A 640 -305 -168 11. 9 A 114 -173 -64 19. 3 Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 15
Pumping Unit Rating w/Structure In real world operating situation, the free fall speed of the rods and the Pumping Unit Stroke Length determine maximum pumping speed. Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 16
Fatigue Effects (F. V. Lawrence) Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 17
Fatigue Effects (Con’t) Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 18
Fatigue Effects (Con’t) • API RP 11 BR discusses Modified Goodman Diagram (MGD) – Based on R. R. Moore fatigue (1920 s) – Assumed 10 Million Cycles life (10 spm*24 hr/day) = 23 months ~2 years) • 1993 Hein & Hermanson published SPE 26558 “New Look at Sucker Rod Fatigue Life” – Provided history of development of MGD – RP 11 BR MGD conservative – Non-linear approach (Gerber Parabolic Relation) may be more appropriate • Overloaded rods (~125%) • 50, 000 Cycles (10 spm *24 hr/day = 115 months ~10 years) Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 19
Fatigue Effects (con’t) • API RP 11 L “Design Calculations for Sucker Rod Pumping Systems: PPRL = Wrf + [(F 1/Skr) * Skr] MPRL = Wrf – [(F 2/Skr) * Skr] PT = (2 T/S 2 kr) * Skr * S/2 * Ta Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 20
6 Basic Loads & Load Range LOAD RANGE represents the load range between the peak and minimum polished rod loads. Load ranges are used in calculating max and min sucker rod stresses. Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 21
Fatigue Effects (con’t) • Load Range (PPRL – MPRL) thus effects cumulative stress (strain) damage • Smaller load range – Longer fatigue life – Less work – Less HP • Larger load range – Shorter fatigue life – More work – More HP Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 22
Well Design Example • One main criteria for rod string design is to match pump displacement to well production capacity. • PD = 0. 1166 * S * N * D 2 • WC/0. 85 < PD < WC/0. 65 • OR PD = ~120% to ~150% * WC Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 23
Well Design Example • Used Beam Pump Program • Assumed Well: H=L= 5000’ TAC @ 4940’ D = 1. 5” 65 - D grade rods G = 1. 0 0 sinker bars Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 24
Well Example – results summary S N Fo/SKR N/No' Sp PD SV TV PPRL MPRL PTpr HPpr 74 7. 7 0. 2868 0. 1414 56. 0 113. 1 5852 9677 10, 992 4, 714 135. 4 4. 5 9. 8 0. 2868 0. 1800 58. 4 150. 1 5852 9677 11, 336 4, 190 147. 7 6. 0 12. 3 0. 2868 0. 2315 60. 8 200. 9 5852 9677 11, 850 3, 605 165. 2 8. 7 6. 4 0. 2467 0. 1176 67. 0 113. 2 5852 9677 11, 002 4, 914 138. 1 4. 5 8. 3 0. 2467 0. 1525 69. 2 150. 6 5852 9677 11, 358 4, 446 174. 7 6. 1 10. 6 0. 2467 0. 1947 72. 1 200. 5 5852 9677 11, 801 3, 792 196. 4 8. 5 5. 3 0. 2122 0. 0973 81. 3 113. 0 5852 9677 11, 001 5, 055 182. 0 4. 4 7. 0 0. 2122 0. 1286 82. 6 151. 7 5852 9677 11, 389 4, 660 201. 6 6. 1 9. 0 0. 2122 0. 1653 84. 7 200. 0 5852 9677 11, 825 4, 049 228. 6 8. 4 2. 9 0. 1263 0. 0532 148. 0 112. 8 5852 9677 10, 662 5, 407 268. 0 4. 5 3. 9 0. 1263 0. 0707 148. 9 150. 4 5852 9677 11, 064 5, 169 286. 7 6. 0 5. 1 0. 1263 0. 0938 149. 8 200. 9 5852 9677 11, 567 4, 821 317. 4 86 100 168 Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 25
Well Example (constant production) S N Fo/Skr N/No' Sp PD PPRL MPRL Load Range PTpr HPpr 74 9. 8 0. 2868 0. 1800 58. 4 150. 1 11, 336 4, 190 7, 146 147. 7 6. 0 86 8. 3 0. 2467 0. 1525 69. 2 150. 6 11, 358 4, 446 6, 912 174. 7 6. 1 100 7. 0 0. 2122 0. 1286 82. 6 151. 7 11, 389 4, 660 6, 729 201. 6 6. 1 120 5. 6 0. 1768 0. 1030 101. 9 149. 9 11, 304 4, 897 6, 407 229. 1 6. 0 144 4. 6 0. 1473 0. 0839 125. 2 150. 1 11, 180 5, 052 6, 128 257. 5 6. 0 168 3. 9 0. 1263 0. 0707 148. 9 150. 4 11, 064 5, 169 5, 895 286. 7 6. 0 Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 26
Summary • Long & Slow has been sold as way to reduce fatigue failures due to less cycles. • Short & fast vs. long & slow are relative terms. • Fatigue theory shows load range most important to fatigue life. • 1920’s fatigue life of 10, 000 cycles not represent current rod manufacturing and well optimization. 50, 000 cycles should be obtainable. (FF ~0. 10) • Typically for same production, same work required to lift to surface, so ~PPRL and HPpr same until very long stroke. Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 27
Summary (con’t) • As S increases MPRL increases due to dynamic effects which reduce load range. • While longer/slower may reduce load range, PTpr and required PT for unit increased. • Slowing down long S design may be problematic since efficiency reduces for smaller sheaves. • Jack shaft may be used to provide additional speed reduction, but further reduces power transmission efficiency and increases costs. • Sinker bars will provide same dynamic effect of increasing MPRL and reducing load range for shorter/faster operation. • Optimization of pumping equipment might say ‘shorter/faster’ w/ sinker bars is more operational effective. Oct. 4 - 7, 2005 Beam Pumping Workshop - ©OGOS 28
Beam Pumping Workshop Houston, Texas October 4 - 7, 2005 Long & Slow vs. Short & Fast Norman W. Hein, Jr. , P. E. – President & Managing Director Oil & Gas Optimization Specialists, Ltd. (OGOS), Midland, TX. nwhein@cox. net 432. 694. 3678
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