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Copyright 2009, Society of Petroleum Engineers Inc.

This paper was prepared for presentation at the 2009 SPE Production Operations. Symposium held 4 -8 April 2009 in Oklahoma City, Oklahoma, USA.

This paper was selected for presentation by an SPE Program Committee following review of information contained in a proposal submitted by the author(s). Contents of the paper, aspresented, have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material, as presented, does not necessarily reflect any positionof the Society of Petroleum Engineers, its officers, or members. Papers presented at SPE meetings are subject to publication review by Editorial Committees of the Society of PetroleumEngineers. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of the Society of Petroleum Engineers is prohibited.Permission to reproduce in print is restricted to a proposal of not more than 300 words; illustrations may not be copied. The proposal must contain conspicuous acknowledgment of whereand by whom the paper was presented. Write Librarian, SPE, P.O. Box 833836, Richardson, TX 75083-3836, U.S.A., fax 01-972-952-9435.

AbstractThe need for better understanding of sucker rod pumping

process is heavily required. Many problems are still under

investigation such as determination of the fluid level fromsurface, selection of the optimum pump size and the

required pump setting depth to maximize the pumping

rate in a particular well. The main purposes of this studyare to investigate effects of fluid level over pump, pump

size, and pump setting depth on the sucker rod

performance. These goals are achieved using the Artificial

Sucker Rod Pump (ASRP) design simulator with actualfield data.

The results show that applying good fluid level from the

surface and increasing the plunger stroke consequentlyincrease the resultant pumping flow rate. Furthermore,

good fluid level yields high pump intake pressure andresults in a good pump fillage, which increases the pump

efficiency. In addition, the analysis of the effect of pumpsize on rod stress shows that the increase of pump size

increases the rod stress and increases the pump flow rate.

Therefore, the plunger size must be selected according to

both the required flow rate and the allowable sucker rod

stress. With respect to the effect of the pump setting depthon the performance of the sucker rod pump, the increase

of the pump setting depth reduces the pump flow rate and

increases the rod stress. Actual Egyptian field data is used

for the purpose of achieving this simulation investigationof the above-mention effects.

1. Introduction and Literature ReviewThe energy crisis confronting the world now has made the

optimum selection and operating of the oil field

production equipment to be a must. This is certainly verytrue of oil field pumping units, especially for the

developed/depleted wells. It is imperative to size the

pumping unit according to the well conditions as accurateas possible. In the mean time, it is equally important to

operate the pumping unit within its optimum rate to avoid

the costly downtime due to breakdown. This meansobtaining a better understanding of the important factors

affecting the pump performance such as the influence of

the fluid level from surface, the effect of pump size and

pump setting depth on both the pump flow rate and the

rod stress of the sucker rod as an artificial lift method.

The purpose of the artificial lift is to maintain a reduced

bottom-hole pressure so that the producing formation can

provide the desired flow rate of reservoir fluids. There aremany artificial lift systems1-6 currently applicable in the

petroleum industry. These systems include: (1) Sucker

rod pumping (Beam pumping), (2) Gas lift, (3) Electrical

submersible pumping, (4) Hydraulic (Piston and Jet)pumping, (5) Plunger (Free-piston) lift, and (6) other

methods such as: Ball-pump and Gas-actuated pump. Thebeam pumping system3 is the most popular artificial lift

system all over the world.The sucker rod pumping

system1,3,5,6consists mainly of five parts including (1) Thesubsurface sucker rod-driven pump, (2) The sucker rod

string, (3) The surface pumping equipment, (4) The power

transmission unit, and (5) The prime mover. The pump1consists simply of a working barrel (or linear) suspended

on the tubing; the plunger is moved up and down inside

this barrel by the sucker rod string. At the surface, the unit

and prime mover provide the oscillating motion to the

sucker rod string and then to the subsurface pump. Suckerrods are available in different sizes including the

following standard sizes 5/8, 3/4, 7/8, 1.0, and 17/8 // in

diameter. Two valves are installed at the bottom of theworking barrel. These valves are (a) standing valve (SV):

it is a stationary ball-and-seat valve, and (b) travelling

valve (TV): it is located in the plunger.

Maintaining the required bottom-hole pressure is the basis

for the design procedure of any artificial lift installation

regardless of the type of lift installed. All methods2, 3

ofthe design of a sucker rod pumping system confirmed that

the fluid level over the pump and the setting depth of the

pump represent two of the minimum mainly required

SPE 120681

Effects of Subsurface Pump Size and Setting Depth on Performance ofSucker Rod Artificial LiftA Simulation ApproachShedid A. Shedid, Texas A&M University at Qatar

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2 SPE 120681

information to start the design procedure. Han et al7

showed that the setting depth of the subsurface pump is an

important predetermined parameter for the process ofpump design, while assuming 100 % pump fillage and a

pumped off conditions. These conditions may not be

consistent with the operated well conditions.

Although sucker rod pumping has been widely applied in

the oil industry as one of the most popular artificial liftmethod, it still has many questions seeking satisfactory

answers. These questions may include what are the

optimum pump setting depth and the plunger sizeproviding the maximum pumping rate for a specific

producing well?, what is the required fluid depth over the

pump in the annulus during pumping?, and what is the

influence of rod stress on the selection of the pump size,

and consequently on the resultant flow rate?.

Actual field data of some Egyptian oil fields including:

Aman, North East, and Meleiha are used to achieve this

study. In addition, this study investigates mainly the

effects of fluid over pump, pump size, and pump settingdepth on the sucker rod pump performance.

2. Sucker Rod Pumping Analysis

The analysis of the sucker rod pump has been performed

using the Artificial Sucker Rod Pump (ASRP) design

software called LOADCAL. LOADCAL8 is a design

calculation program for conventional-Mark II-RM- andair balance units. This program uses API-RP-11L

procedure and is based on developing a set of graphs for

the desired unit geometry and pumping conditions byusing a wave equation program. Through the development

of this design software, the wave equation and simulationtechniques are used to mimic pumping conditions andcalculate the loads and displacements.

Three selections are available while using the LOADCALprogram8. These selections include: (1) APIROD:

Predicts pumping unit loadings for standard API rod

strings, (2) SBAR: Predicts pumping unit loadings with

non-standard rod strings and/or sinker bars at the bottomof the string, and (3) TMAX: Determines production and

pumping unit loads for a given maximum torque (A

standard API rod string is assumed). Another set ofselections are also used for the development of the

LOADCAL program and can be used for loading

calculations. These sets involve: (1) Conventional, (2)Mark II, (3) RM Unit, and (4) Air Balance. This current

study has been achieved using the following twoselections, which satisfy the needs for the selected well

and pump conditions under investigation: (1) APIROD,

and (2) Mark II. It is important to indicate the differencebetween the pump depth and the fluid level over pump.

The pump depth refers to the distance from surface to

pump (ft). The fluid level refers to the distance fromsurface to fluid level in the producing well (ft).

The output of the LOADCAL program8 contains thefollowing information: (1) Torque, (2) Peak polished rod

load (PPRL), (3) Minimum polished rod load (MPRL),

(4) The required counterbalance effect (CBE) in pounds,

(5) Pumping speed in stroke per minute, (6) Polished rodhorsepower (PRHP), (7) The production at 100 %

efficiency in barrels per day, and (7) The production at 80

% efficiency in barrels per day. For the purpose of

achievement this simulation investigation study, the peak

polished rod load (% Goodman diagram) and theproduction at 80 % efficiency are used since all of the

other output parameters are kept constant as inputs.

With respect to the selection of the pump size, the pumpdisplacement3 for given plungers size and for given

combination of pumping speed and stroke can be

determined from the following equation:

xNKxSPD P= (1)

Where

PD = Total pump displacement, B/D

K = A pump constant, depending upon the plunger sizeand given by K = 0.1484 AP.

AP = Cross-sectional area of the pump plunger, sq. inch

SP = effective plunger stroke, inch

N = Pumping speed, spm.

The volumetric pump efficiency (EV) can be determinedby:

PDQEV /= (2)

Where

Q = Actual production rate at the surface, B/D

The volumetric pump efficiency (EV) is influenced by

pump slippage and produced fluid properties such as gas

constant, foaming characteristics, and fluid shrinkagefactor.

With respect to the stress of the rod string, the maximum

anticipated stress of a tapered rod string has not to exceed

the safe allowable working stress (usually 30,000 psi).

The maximum stress at the top of the entire rod string

(also called Peak Polished Rod Load, PPRL) can beexperimentally measured or calculated as follows:

Top

Max

A

W

toptheatStress =

(3)

Where

WMax= Maximum weight of the rod string, lb

ATop = Cross-sectional area of the top rod string section,

sq. inch. The maximum stress5of the rod string depends

mainly on the grade of the used rod. For API Grade C

rods, the maximum allowable stress is given by:

SA= (22,500 + 0.5625 Smin) x S. F (4)

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SPE 120681 3

And for API Grade D rods, the maximum allowable stress

is given by:

SA= (28,750 + 0.5625 Smin) x S. F (5)

Where

Smin= Minimum rod stress (either calculated or measured)

S F = Service Factor (S F = 1.0 for API Grades C and D)

3. Results and Discussions

The flow rate (at 80 % pump efficiency) and stress

load for sucker rods (Norrris, N97) versus fluid over

the pump have been estimated for the well and pump

conditions, listed in Tables 1 and 2. These

conditions represent a wider range than actual and

currently used conditions in the Egyptian oil fields.

The flow rate (at 80 % pump efficiency) is

calculated considering the plunger/barrel slippageeffect, well fluid properties and the shrinkage factor.

The rod stress of the sucker rod pump is alsocalculated as a percentage of Goodman diagram

considering Artificial Service Factor (ASF) to be

unity.

3.1. Effects of Fluid Level from Surface andFluid over Pump

Seven different fluid levels from surface are used to

investigate this effect, as shown in Figs. 1 to 5.The

influences of fluid level on required power,maximum load, net production, maximum torque,

and rod loading are shown in Figs. 1 to 5,

respectively. The results indicated that an increase in

net production occurs with a decrease in fluid level

from surface (or increase of fluid over pump). Three

different fluid levels over the pump are used to

investigate the influence of fluid over pump on

pump flow rate and rod stress. These fluid levels are:

(1) Zero ft (pump is set at the same fluid level), (2)

500 ft above the pump and (3) 1,500 ft above the

pump. Using well and pump conditions listed in

Table 2 and for pump setting depth equals 5,500 ft,both the pump rate (at 80 % efficiency) and the rod

stress (% of Goodman diagram) are calculated using

the LOADCAL program. One-hundred-eight runs

are performed and the results are tabulated as shown

in Table 3. Another set of 108 runs is made but for

pump setting depth of 5,900 ft, Table 4. The results

indicated that the increase of fluid over pump

increase the attained flow rate for different stroke

lengths and different stroke per minutes. Results

concerning the investigation of this effect are shown

in Tables 3and 4. These results indicate an increase

of the pump flow rate when the fluid level over

pump increases. The good fluid level over the pumpreduces the rod stretch and consequently increases

the effective plunger stroke. This consequently leads

to an increase in the pump flow rate due to the

resulting high pump intake pressure. In addition, the

increase of fluid level leads to a reduction in sucker

rod stress, due to the buoyancy effect. A conclusion

can be drawn that the increase of fluid level leads to

an increase of pump flow rate and a decrease of rod

stress, for different values of stroke length, pump

speed, and pump setting depth.

3.2. Effect of Pump Size

Four different pump sizes are selected to study this

effect on the artificial sucker rod pump performance.

These pump sizes include: 2.5, 2.25, 2.0, and 1.75

inch. For each pump size, Nine runs are made fordifferent values of stroke length (112, 128, and 144

inch). Therefore, the total number of performed runs

is thirty-six for each fluid level. Two other sets (each

of 36 runs) are made for other two fluid levels of

500 and 1,500 ft respectively. Results are tabulated

in Tables 3 for pump setting depth of 5,500 ft and in

Table 4 for pump setting depth of 5,900 ft. There is

an optimum pump-bore, which provides effective

stroke travel and maintains moderate speed of

operation. Larger plunger provides unnecessarily

high load upon equipment while smaller plunger

leads to high pumping speed and increasesacceleration (inertial) effects. Equation 2 is usually

used to select the most suitable pump size based on

the actual production rate at the surface and the

pump displacement. The main drawback of this

equation is that it does not consider the effect of

increasing the flow rate on the rod stress. Therefore,

the current study generates satisfactory results for

filling this gap, treating this lack, and overcoming

this drawback of equation 2. The results of this

study, tabulated in Tables 3 and 4, indicate that

using larger pump size increases the flow rate and

also increases the sucker rod stress. Then, Using asmaller sucker rod size can reduce the rod stress of

the sucker rod pump without reducing the well flow

rate. The application of this beneficial conclusion is

expected to reduce the rod parted phenomena and

the downhole pump failures.

More sizes of pumps are also investigated and

graphically plotted in Figs. 6 to 10. The influence of

pump diameter on surface maximum load, power

required, existing maximum torque, rod loading, and

average pumping speed, are shown respectively in

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4 SPE 120681

Figs. 6 to 10. The results indicated that the minmum

maximum surface load is attained when pumpdiameter of 1.50-in is used and the increase of pump

size increases to maximum load and decreases the

power required.

3.3. Effect of Pump Setting Depth

Two different pump setting depths (5,500 and 5,900ft) are considered for studying this effect on sucker

rod pump performance. For each selected pump

depth, 108 runs are performed considering different

fluid levels (Zero, 500, and 1,500 ft), different pump

sizes (2.5, 2.25, 2.0, and 1.75 inch), different strokelengths (112, 128, and 144 inch), and different pump

speeds (6, 8, and 10 spm). The results of using pump

depth equal to 5,500 ft is listed in Table 3, while the

results of pump depth equals 5,900 ft is shown in

Table 3. The increment of pump setting depthcauses an increment of the length of sucker rod

string. This increment of pump setting depth yields

an increase of the rod stretch and decreases the

effective stroke length. Consequently, the increase of

pump setting depth leads to a decrease in the

resulting flow rate. This conclusion can be obtained

from a comparison the results of Tables 3 and 4.

The reduction in flow rate can be attributed to the

increase of sucker rod stress due to the increase of

rod weight and the resulting increase of friction (due

to the increase of the number of rod connections).

4. Field Applications

Three wells are selected from three different

Egyptian oil fields, including North East, Aman, and

Meleiha, to be used as field applications of this

study, Table 1. These selected wells and their pump

conditions are then used to define the applied range

of well and pump conditions, as shown in Table 2.

In addition to studying the effects of fluid level over

pump, pump size, and pump setting depth on the

performance of the sucker rod performance, the

obtained output of this study can be used effectivelyfor: (a) mechanical evaluation of the pump

performance, and (b) determination the importance

of considering the pump fillage and friction effects.

With respect to well NE-20, North East Field, the

calculated flow rate is 611 B/D while the measuredone is 540 BOPD with 36 Mcf/D gas. This deviation

is mainly attributed to the existence of gas since the

used design method (API-RP-11L) assumes 100 %

pump filling. For the well A-21, Aman oil Field, the

calculated flow rate is 293 B/D while the measured

one is 105 BOPD and 1.0 BWPD. Therefore, this

well is expected to bear some mechanical problemsand the well operating conditions should be re-

evaluated. For the well M-1, Meleiha oil Field, the

calculated flow rate is 315 BOPD with 27.4 Mcf/D

gas while the measured liquid flow rate is 550 B/D.

The difference is attributed to the existence of the

fluid pound. Table 1 listed all the used field data,

the program results of flow rate and rod stress (%

Goodman diagram) and comment on the results.

5. Conclusions

This simulation study was undertaken usig actualfield data to investigate the effects of fluid level

from surface, pump diameter, and pump setting

depth on the performance of sucker rod pump

performance. The following conclusions are

attained:1. The pump flow rate increases with the increment

of the fluid level over the pump while the pump

rod stress decreases, for fixed values of pump

speed, stroke length, and pump size of the

sucker rod pump.

2. The increase of pump size increases the flowrate and decreases the rod stress. Therefore, the

plunger size of the pump has to be selected to

gain the desired flow rate and to avoid the

overload stress condition. This conclusion is

valid for different conditions of fluid level,

pump setting depth, and stroke length.3. The decrease of pump setting depth increases the

pump flow rate and decreases the rod stress. The

increase of the resulting flow rate is mainly

attributed to the increase of pump intake

pressure while the reduction of the resultingstress is mainly attributed to the reduction in

length and weight of the sucker rod.

6. Recommendations

1. The results of this study recommend using 2.25//

pump size because these pumps are moresuitable for flow rate range of 500 to 600 BPD

with stroke length range of 8 to 10 inch and fluid

level over pump > 500 ft.

2. The results proves that the 2.5// pumps have tobe installed to produce more than 600 BPD,

although higher rod stress (more than 70 % of

Goodman diagram with artificial service factor =

1.0) is encountered. This application has to be

limited to the only required special cases.

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SPE 120681 5

3. In order to avoid the rod partition and to reducethe spare parts, the following recommendationscan be applied: (a) the Electrical Submersible

Pump (ESP) could replace the 2.5// sucker rod

pump after a detailed reservoir analysis of

well/pump conditions, and (b) the 2.5// pumps

could be installed in wells producing more than

600 BPD and having a high value of water cut.

4. The advantages of using 1.75// pump sizeinstead of 2.0// are not so evident to justify their

application for lower flow rates in the future.

Nomenclature

ASRP Artificial Sucker Rod Pump

AP Cross-sectional area of the pump plunger,

sq.

inch

ATop Cross-sectional area of the top rod string

section, sq. inch

CBE Required Counterbalance Effect

K Pump constant, depending upon the plunger

size and given by K = 0.1484 AP.

EV The volumetric pump efficiency

MPRL Minimum Polished Rod Load

N Pumping speed, spm.

PD Total pump displacement, B/D

PPRL Peak Polished Rod Load

PRHP Polished Rod Horsepower

Q Actual production rate at the surface, B/D

SA Maximum allowable stress, psi

Smin Minimum rod stress (either calculated or

measured)

S F Service Factor (S F = 1.0 for API Grades C

and D)

SP Effective plunger stroke, inch

WMax Maximum weight of the rod string, lb

Subscripts

P Plunger

Min Minimum

V Volumetric

References

1. Nind, T. E. W. :Principles of Oil WellProduction: McGraw-Hill Book Company,

Second Edition, New York, Chapter 9, 1981, P.

240-58.

2. Gibbs, S. G., Predicting the Behavior of a

Sucker Rod Pumping System, SPE ReprintSeries, No. 12, published by the Society of

Petroleum Engineers of AIME, Edition of 1975,

pp. 13-22..

3. Brown, K. E., Overview of Artificial LiftSystems, Journal of Petroleum Technology,

October, 1982, pp.2384-96.

4. Guirados, C.; Sandoval, J. Rivas, O. andTroconis, H., Production Optimization of

Sucker Rod Pumping Wells Producing Viscous

oil in Boscan Field, Venezuela, SPE 29536,

The Production Operation Symposium,

Oklahoma City, Ok, 1995.5. Hirschfeldt, M., Martinez, P., and Distel, F.

Artificial Lift Systems Overview and Evolution

in a Mature Basin: Case Study of Golfo San

Jorge, SPE 108054, the 2007 SPE Latin

American and Caribbean Petroleum EngineeringConference, Buenos, Argentina, 15-18 April,

2007.

6. Ghareeb, M., Shedid, S. A., Ibrahim, M.,Simulation Investigations for Enhanced

Performance of Beam Pumping System for DeepHigh Volume Wells, SPE 108284, the 2007

International Oil Conference and Exhibition inMexico, Veracruz, Mexico, 2730 June, 2007.

7. Han, D., Wiggins, M., and Menzie, D., AnApproach to the Optimum Design of Sucker-

Rod Pumping Systems, SPE 29535, presented

at the Production Operation Symposium held in

Oklahoma City, OK, USA, 2-4 April, 1995, pp.

855-866.

8. Instructions for the use of LOADCAL (IBMVersion)-Internal Edition: Lufkin Industries,

Inc., Texas, 1998, USA.

9. Clegg, J. D., Improved Sucker Rod Design

Calculations Southwestern Petroleum ShortCourse, 1988.

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Table 1- Well and Pump Data of Three Egyptian Oil Fields

Field North East Aman Meleiha

Well Number North East-20 Aman-21 Meleiha-1Pump type Lufkin Mark II Lufkin Mark II Lufkin Mark II

Stroke length 144 inch 144 inch 144 inch

Pump diameter 2.25 inch 2 inch 2.25 inch

Pump intake 5,600 ft 5,625 ft 5,785 ft

Oil API 40 degree 40 degree 40 degree

Water sp. gravity 1.05 1.05 1.05

Oil production rate 540 BOPD 105 BOPD 315 BOPD

Water prod. Rate 0.0 BWPD 1.0 BWPD 0.0 BWPD

Gas production rate 36 Mcf/d 0.0 Mcf/d 27.4 Mcf/d

Surface temperature 70 oF 70 oF 70 oF

Bottom-hole temp. 180 oF 180 oF 180 oF

Pump efficiency 97 % 100 % 77 %

LOADCAL. Results

Flow Rate 611 B/D 293 B/D 550 B/D

Rod Stress 58.3 % 46.9 % 57.3 %

Comment Fluid pound exists ------- Fluid pound exists

Table 2 Applied Well and Pump Conditions

Type of surface unit Lufkin Mark II

Stroke/minute 6, 8, and 10.

Water cut 0 % and 50 %

Well head pressure 50 psi and 100 psi

Produced crude oil API 40 degree

Pump plunger size 2.5//, 2.25//, 2.0//and 1.75//

Pump setting depth 5,500 ft for runs in Table 3 and

5,900 ft for runs in Table 4

Type of rod string Norris 97 (high tensile-strength rod)

Produced crude oil specific gravity 0.82

Sucker rod string configuration size 87 ( 1//+ 7/8//)

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SPE 120681 7

Table 3- Calculated Values of Pump Flow Rate and String Load for

Different Pump Sizes, Fluid Level over Pump, Stroke Length,

and Stroke per Minute (Pump Setting Depth = 5,500 ft).

Operating Conditions

Pump Depth = 5,500 ft

Well Head Pressure (WHP) = 50 to 100 psi

Fluid Pump 112 128 144

Over Size Stroke Length(in) Stroke Length(in) Stroke Length(in)

Pump Goodman 6 8 10 6 8 10 6 8 10

(ft) Diagram SPM SPM SPM SPM SPM SPM SPM SPM SPM

2.5// 296 410 532 355 486 636 412 567 739

% 57.4 57.4 62.9 53 59.6 66.3 54.6 61.6 69.6

2.25//

256 353 460 302 417 543 349 480 624

0 % 44.3 50.2 56.5 46 52.5 60 45.2 55.3 63.1

2// 213 294 362 250 344 445 287 393 507

% 38.2 44.1 50.7 40.9 47.3 53.7 43.5 60.6 66.7

1.75 171 235 302 200 273 350 226 311 396

% 34.1 39.8 44.9 36.8 43.1 48 39.4 46.3 51

2.5// 307 422 549 364 501 652 421 579 756

% 48.3 54.3 60.2 49.9 56.5 63.6 51.5 58.7 66.9

2.25// 262 361 471 306 425 553 443 487 632

500 % 41.7 47.6 54.3 43.8 50.3 57.7 46.4 53.4 60.6

2// 217 299 367 254 348 449 291 396 512

% 36.8 42.6 45.7 39.5 45.8 51.7 42.1 49 54.7

1.75 174 237 305 202 275 353 230 313 401

% 33 38.7 43.3 36.7 41.9 46.4 38.3 45.1 49.5

2.5// 324 446 552 361 525 683 439 602 761

% 42 47.9 54.7 44.1 50.6 58 46.7 53.8 61

2.25// 274 377 489 321 439 568 368 502 647

1500 % 37.4 43.3 49.5 40.1 46.6 52.2 42.7 49.8 55.6

2// 225 306 396 262 358 459 299 407 521

% 33.9 39.6 44.5 35.6 42.9 47.7 39.2 46.1 50.7

1.75 178 243 311 207 281 359 234 319 407

% 30.5 35.4 40.1 32.8 39 43 33.9 40.3 45.3

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Table 4- Calculated Values of Pump Flow Rate and String Load for

Different Pump Sizes, Fluid Level over Pump, Stroke Lengths,

and Stroke per Minute (Pump Setting Depth = 5,900 ft).

Operating Conditions

Pump Depth = 5,900 ft

Well Head Pressure (WHP) = 50 to 100 psi

Fluid Pump 112 128 144

Over Size Stroke Length(in) Stroke Length(in) Stroke Length(in)

Pump Goodman 6 8 10 6 8 10 6 8 10

(ft) Diagram SPM SPM SPM SPM SPM SPM SPM SPM SPM

2.5// 265 395 504 427 474 606 399 554 712

% 65 60.6 66.3 56.3 63.9 69.4 58.6 55.9 73.2

2.25// 248 334 441 294 409 525 340 474 609

0 % 47.6 53.7 59.4 49.4 55.6 63.5 51.3 57.9 67.4

2// 206 290 372 306 241 437 262 390 500

% 40.9 46.4 54.1 43.1 49 57.6 45.7 52.2 60.2

1.75 168 233 298 196 271 346 225 309 393

% 35.8 41.1 47.6 38.4 44.4 50.3 41 47.6 52.9

2.5// 294 406 522 351 488 626 406 568 729

% 51.9 65.2 63 53.8 60 67 55.6 52.7 70.9

2.25// 254 353 453 300 418 537 347 483 620

500 % 45 51 57.5 47 63.1 61.6 49 55.4 66.2

2// 212 295 380 249 345 442 286 395 505

% 39 44.2 52.6 41.6 47.5 55.2 44.1 50.7 57.8

1.75 171 236 301 199 247 349 227 312 397

% 34.6 40 45.7 37.3 43.3 48.4 39.8 46.5 50

2.5// 313 434 558 370 515 662 427 595 765

% 45.7 51.8 58.3 47.7 53.9 62.4 49.7 56.2 66.2

2.25// 266 371 477 313 434 557 360 491 636

1500 % 40.1 45.5 53.7 42.6 48.5 55.7 45.2 51.8 59.3

2// 220 305 390 257 355 452 294 404 515

% 35.8 41.2 47.6 38.5 44.5 50.3 41.1 47.8 52.9

1.75 176 241 307 204 279 355 232 317 403

% 32.2 37.3 41.8 34.9 41 44.6 37.4 44.2 47.3

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SPE 120681 9

30

35

40

45

50

55

60

65

0 1000 2000 3000 4000 5000 5950

Fluid level from surface, ft

Powerrequired,hp

Fig.1. Effect of fluid level from surface on required power.

10000

12000

14000

16000

18000

20000

22000

24000

26000

28000

30000

0 1000 2000 3000 4000 5000 5950

Fluid level from surface,ft

Peakpolishedrodloa

Fig. 2. Effect of fluid level from surface on surface maximum load.

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10 SPE 120681

Net bpd at 100% eff.

600

650

700

750

800

850

0 1000 2000 3000 4000 5000 5950

Fluid level from surface, ft

netproduction

Fig. 3. Effect of fluid level from surface on o net production at 100 % efficiency.

0

200

400

600

800

1000

1200

0 1000 2000 3000 4000 5000 5950

Fluid level from surface, ft

peaktorque,in-Ib

Fig. 4. Effect of fluid level from surface on existing maximum torque.

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SPE 120681 11

0

10

20

30

40

50

60

70

80

0 1000 2000 3000 4000 5000 5950Fluid level from surface, ft

RodLoading%

Fig. 5. Effect of fluid level from surface on rod loading.

20000

22000

24000

26000

28000

30000

2.75 2.5 2.25 2 1.75 1.5 1.25

Subsurface pump diameter, in

SurfaceMaxL

oad(lbs)

Fig. 6. Effect of subsurface pump diameter on surface maximum load.

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0

20

40

60

80

100

120

140

2.75 2.5 2.25 2 1.75 1.5 1.25

Subsurface pump diameter, in

PowerReq

uired,

Fig. 7. Effect of subsurface pump diameter on power required.

600

700

800

900

1000

2.75 2.5 2.25 2 1.75 1.5 1.25

Subsurface pump diameter, in

ExistingM

axTorque(min-lbs)

Fig. 8. Effect of subsurface pump diameter on existing maximum torque.

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40

45

50

55

60

65

70

2.75 2.5 2.25 2 1.75 1.5 1.25

Subsurface pump diameter, in

RodLoading,

%

Fig. 9. Effect of subsurface pump diameter on rod loading.

0

2

4

6

8

10

12

14

16

2.75 2.5 2.25 2 1.75 1.5 1.25

Subsurface pump diameter, in

AveragePumpingSpeed(SPM)

Fig. 10. Effect of subsurface pump diameter on averaging pumping speed.