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Beam Pumping Workshop Houston, Texas October 4 - 7, 2005 Long & Slow vs. Short & Fast Norman W. Hein, Jr., P. E. – President & Managing Director Oil &

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Presentation on theme: "Beam Pumping Workshop Houston, Texas October 4 - 7, 2005 Long & Slow vs. Short & Fast Norman W. Hein, Jr., P. E. – President & Managing Director Oil &"— Presentation transcript:

1 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.

2 Oct , Beam Pumping Workshop - ©OGOS2 Let’s Vote How should pumping units be operated? Long & Slow? Short & Fast?

3 Oct , Beam Pumping Workshop - ©OGOS3 Is There a Preference? YES!

4 Oct , Beam Pumping Workshop - ©OGOS4 Content Speed Background –Acceleration Factor –Theoretical Max Speed Pumping Unit Rating –API Spec –Lufkin Recommendation Gear Box Pumping Unit Fatigue Effects Well Design Examples

5 Oct , Beam Pumping Workshop - ©OGOS5 Speed Background

6 Oct , Beam Pumping Workshop - ©OGOS6 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.

7 Oct , Beam Pumping Workshop - ©OGOS7 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 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 = –But seldom is well straight –Typically pumping other than fresh water

8 Oct , Beam Pumping Workshop - ©OGOS8 SPM vs. S PR (fpm)

9 Oct , Beam Pumping Workshop - ©OGOS9 Speed Background (con’t) Gipson & Swaim recommended for design: < C < 0.3 (Shallow wells) > 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.

10 Oct , Beam Pumping Workshop - ©OGOS10 Pumping Unit Rating API Spec 11E “Pumping Units” covers –Gear Reducer (Box) –Unit Structure Gear Reducer performance based on AGMA Standard Originally based on 20 SPM for all gear reducers IN 1981, API revised reducer rating for 456 & larger units

11 Oct , Beam Pumping Workshop - ©OGOS11 Pumping Unit Rating (con’t) API larger unit speed rating: Peak Torque Rating (in-lbs)SPM 456, , , ,280, ,824, ,560,00011

12 Oct , Beam Pumping Workshop - ©OGOS12 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 D4025.1D D5740.4D D8055.8D D D D160115D D228160D D *assumes prime mover speed of 870 rpm

13 Oct , Beam Pumping Workshop - ©OGOS13 Pumping Unit Rating w/Structure Pumping Unit Size Max. SPMPU SizeMax. SPM C (305) C C (305) C C C C C C C C C C C C C C C C C C C C C C

14 Oct , Beam Pumping Workshop - ©OGOS14 Pumping Unit Rating w/Structure Pumping Unit SizeMax. SPMPU SizeMax. SPM M M M M M M M M M M M M M M M M M M

15 Oct , Beam Pumping Workshop - ©OGOS15 Pumping Unit Rating w/Structure Pumping Unit SizeMax. SPMPU SizeMax. SPM A A A A A A A A A A A A A A A A

16 Oct , Beam Pumping Workshop - ©OGOS16 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.

17 Oct , Beam Pumping Workshop - ©OGOS17 Fatigue Effects (F. V. Lawrence)

18 Oct , Beam Pumping Workshop - ©OGOS18 Fatigue Effects (Con’t)

19 Oct , Beam Pumping Workshop - ©OGOS19 Fatigue Effects (Con’t) API RP 11BR discusses Modified Goodman Diagram (MGD) –Based on R. R. Moore fatigue (1920s) –Assumed 10 Million Cycles life (10spm*24hr/day) = 23 months ~2 years) 1993 Hein & Hermanson published SPE “New Look at Sucker Rod Fatigue Life” –Provided history of development of MGD –RP 11BR MGD conservative –Non-linear approach (Gerber Parabolic Relation) may be more appropriate Overloaded rods (~125%) 50,000,000 Cycles (10spm *24hr/day = 115 months ~10 years)

20 Oct , Beam Pumping Workshop - ©OGOS20 Fatigue Effects (con’t) API RP 11L “Design Calculations for Sucker Rod Pumping Systems: PPRL = Wrf + [(F1/Skr) * Skr] MPRL = Wrf – [(F2/Skr) * Skr] PT = (2T/S 2 kr) * Skr * S/2 * Ta

21 Oct , Beam Pumping Workshop - ©OGOS21 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.

22 Oct , Beam Pumping Workshop - ©OGOS22 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

23 Oct , Beam Pumping Workshop - ©OGOS23 Well Design Example One main criteria for rod string design is to match pump displacement to well production capacity. PD = * S * N * D 2 WC/0.85 < PD < WC/0.65 OR PD = ~120% to ~150% * WC

24 Oct , Beam Pumping Workshop - ©OGOS24 Well Design Example Used Beam Pump Program Assumed Well: H=L= 5000’ 4940’ D = 1.5” 65 - D grade rods G = sinker bars

25 Oct , Beam Pumping Workshop - ©OGOS25 Well Example – results summary SNFo/SKRN/No'SpPDSVTVPPRLMPRLPTprHPpr ,9924, ,3364, ,8503, ,0024, ,3584, ,8013, ,0015, ,3894, ,8254, ,6625, ,0645, ,5674,

26 Oct , Beam Pumping Workshop - ©OGOS26 Well Example (constant production) SNFo/SkrN/No'SpPDPPRLMPRLLoad RangePTprHPpr ,3364,1907, ,3584,4466, ,3894,6606, ,3044,8976, ,1805,0526, ,0645,1695,

27 Oct , Beam Pumping Workshop - ©OGOS27 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 10,000,000 cycles not represent current rod manufacturing and well optimization. 50,000,000 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.

28 Oct , Beam Pumping Workshop - ©OGOS28 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.

29 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

30 Oct , Beam Pumping Workshop - ©OGOS30


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