A Rod Pumping System for California Lift Requirements

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SPEm~~mm-=SPE 11747A Rod Pumping System for California Lift Requirementsby H.C. Tait, Ahtiond Supply Co., Arn?co, Inc.

Copyright 19S3Society of Petroleum Engmeere of AlMEThis paper was presented at tha 1963 California Regional Meeting held m Vantura, California. M@rch23-25, 1983. The material is subjecl to correcfinnby the author. Permission 10copy is restr icted to an abstract of not more thsn 300 words. Wrile SPE, 6200 North Central Expressway, Drawar 64706,Dallss, TX 75206.

ASSTRACTArtificial lift requirementsin California Accepting these Statistics aa reasonablyollflelds cover a full range of demanding operating accurate, we can make some aeeumptionsrelative toand environmental conditions. These extend from artificial lift on the part of Californiatypical demanda of lifting depth and volume, to operators: they are very familiarwith the suckeratypical requirements of heavy crude, thermal rod pumping system, both its advantages andenhancement and the unique environmental limitations; they indicatea significantpreferencerestrictions of our urban sites and offshorefields. fol: this lift method; and, they must be concernedwi~h the edverse effect on operatingcosts of thehtgher than average repatr frequencyof their liftA new rod pumping system has been developed systems.which deala with these requirenent~.Performanceresults to date confirm reducedpower consumption An extensive developmentproject conductedand improvedpumping performance.Combined with the by a California basad design group, aj.med atcompact equipment atze, these characteriettcs developing an lmprovsd rod pumping system, hasappear to offer benefits to Californiaoperatora. attempted to address the operating cost factors as

INTRODUCTION well as the application limitations which are aconcern of operators in the local oilfields.Artificial lift playa a vary afgnificant A primary objectiveof this project was torole in California production operation. One develop a lift system capable of improvedoverallsource reporting industrystatistical , indicates psrformence as a means of reducingoperatingcosts.that 92% of Californiawells are produced by some In achieving this objective, the dasigneraform of artificial lift. This compares to the U.S. drastically changed the configuration of theaverage of 70% pumping unit, resulting in a compact, low profilepackage ideally suited to the aestheticallyTM? same eource estimatesthat 85 to 90% sensitive urban sites and tightly spaced offshoreof U.S. wells on arttflciallift uae the sucker rod applicationsin Californiaproducingfields.pumping method. Csltfornia operators appear tofollow this nattonal Inclination with 90% of new The product of this developmentprogram Isartificial lift tnstallationaduring 1981 reported Identified as the National LIFTRONIC Pumpingas rod pumping systems. 1 system, aa illustrated in Figure 1. Installationsare currently in operation on four CaliforniaThe significance of artificial lift in producing oilwells. They are proving to offerCalifornia operations is fuither emphasizedby one measurable reduction in overall lifting costtsandadditional statistic.Thie reports that 106 repairs improved pumping performance. The compact surfaceper 100 wells on artificial lift were made in equipment is also being recognizedas a realiaticCalifornia operations during 1981 as comparedto answer to the requirement for low visiblityandthe U.S. average of 77 repairs per 100 wells. 1 minimum space in many producingetaas.

Referencesand illustrationsat end of paper.

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2 A ROD PUMPING SYSTEM FOR CALIFORNIA LIFT REQUIREMENTS SPE 11

SYSTBM DESIGN AND EQUIPMENTA full review of the design conceptsandresulting equipment of the LIFTRONIC system hasbeen presented in an earlier SPE paper.2 A briefreview here will be beneficialin describingthepotentialbenefite for Californiaapplications.

Design ConceptsIn addressing the prime developmentobjective of improved overall performance,threemajor design areas were considered; downholepumping efficiency, mechanical equipment design,and operating control of the system.A long stroke pumping actfon, operating ata low cycle rate, was identifiedas most beneficialfor improved downholeefflctency.A minimum strokelength of thirty feet, operating in the threestroke per minute range, wae selected for thedesign. This stroking motion contributes toimproved volumetric efficiencyin the pump throughhigher compression ratio and fewer valve actions.The low cycle rate reduceswear rate and dynamicloading on all downhole components.To further contribute to high operatingefficiency, the mechanical design called forsimplicity, with the most direct drive mechanismpoesible to tranemit stroking power to the rodstring. Uniform counterbalance effect throughoutthe stroke was also desirable for efficientoperation. The resultingdesign met these criteriaand provided an extremly compact machine to serve

California applicationrequirements.The concept for the operatingcontrolwasto constantly monitor operating parameterswhichinfluence overall performance,with the ability tobe ~esponsive to changing conditionsto maintaindesired performance. A mfcropocessor basedelectronic control system was selected to provide

this capability.Equipment and Operation

Figure 2 schematically illustrates theinstallation arrangement of surface and subsurfaceequipment for the LIFTRONIC systern. Majorcomponents include the pumping unit, an operatingcontrol, and the subsurfacewell equipment.Pumping Unit

The pumping unit for this system is a fullyenclosed machine containing two contoured drums(cams) mounted on a common shaft, two load carryingchains (well and counterweight), and two chainidlers. A doublereduction planetarygear reduceris externally mounted on the housing.A fatl-safebrake mounts on the gear reducer. Power istransmitted from an electric motor to the gearraducer through a belt drive.

The use of high strengthchains to carrythe well and counterweightloads accounts for theextremely compact design of the pumping unit. To

achieve a low profile Installation,counterweight.sare suspended in a fifty foot dcaeed hole adjacent to the well. The complpumpi~ unit mounts directly on the wellcounterweightholes.In operation, the load carrying chainswrapped and unwrapped on the contoured cams

effect the strok%ng motton. During the upstrowith the cam rotating in a clockwisedirec(Figure 2), the wellside chaia i?rapsupon iteelsmoothly increase the working diameter on the creaching maximun dimension at the top strreversal.Meanwhile, as the wellside chain wr%tself to maximum working diameter,counterweight chain unwrapa to lowercounterweights, until no chain ramains wrappethe cam at the top reversal.At the optimum point in the strevereal, as determined by the microproceeaothe operating control, moto r power is shut oThis permits cam rotationto respond to the app

loads of the eystem.The imbalanceof these loresulting from differences in the working ra(moment a~ms), brings about the stroke reversAgain under a~ntrol of the microprocessor,mopower is reapplied to complete the downstroke.Figure 3 sl!ows the unit with the coremoved to illustrate the difference in worradii of the chains at the top reversal. A simbut reverse Imbalance of loads occurs at the boetroke reversal.

OperatingControlThe LIFTRONIC operating control tmodular solid-state electronic panel mounted

weather-tight enclosure. It provides all maand automatic control of the operation ofpumping unit. The modular construction ofcontrol panel facilitates servicing by moreplacement, as opposed to electronic citroubleshooting.A cciputermodule, operating in conjuncwith the other control modules within the paprovides intelligence to the control systeperform the followingfunctions:1. Control motor power during strokereversals.2. Monitor operatingparametersandautomaticallyshut-downthe unit if apotentiallyhazardousconditiondevelo3. Automaticallyrestart the unit If theconditton clears.4. Shut-down the unit in avent of a*pump-offcondition,and restartfollowingan adjustable off-time,5. Feed output data to an XT plotter fordynamometercard print-out.

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SPZ 11747 H. C. TAIT-.- ---

APPLICATIONFurther inscription of these centrol Table 1 identifiesbasic specificationsffunctions is covered in the earlier papar.2A the current LIFTRONIC model. Table 2 tabulatsignificant control funtion contributingto enooth nominal pump diaplacenents and depth limits freversals and conservation of power ie the motor various pump boree at a range of pumping speads.control during reversals.

The applic~tion range for this curreAs the pumping unit neara the end of either model generally Kits well conditions requiringthe upstroke or downstroke, the control senses API 228 or API 320 beam pumping unit. A computstroke position plus other operatingparemetera, application design program has been devaloped fand shuts off motor power through solld atate the system in conjunction vith the NABcircuitry to bagin the stroke reversal*While power Corporation. In addition to providing applicatiis off, motor polarity is reversed through design, this also permits analy~is of pradictcontractorswithin the control panel. When the performance of the new system VS. a beam unmotor raaches the synchronous speed range in the installation.reversed direction, power is reappliedthrough alow voltage control.This sequenceprovides emooth Planned developmentof this new lift syetreversals and minimizes current and torque aplkes includes one smaller size, and two higher capaciwhen power ia applied. sizes. The objectivewill be to cover the broadaThe integralpump-off control functionadds possible range of pumping conditions, from moderato high volume lifting requirements,and deptheto the overall performance o f the eyatem by the limlts of sucker rod capacity.quarding againet unnecessary power consumptionor

unwanted equipment damage during a pumped off CaliforniaApplicationscondition.The specific interest here is in tThe dynamometer capability is aleo capabilities of thie new pumping system in dealisignificant in that this data is readilyavailable with the artificiallift requirementso f Californfor diagnostic anelysia of performance through operations. Downhole pumping conditions to considintegral components in the system. The XY plotter should include high temperature and heawy ocan trace position plotted againet polished rod artificial Ifft, highly deviatedwells and even tload, motor speed or motor current.A futura option plafn vanilla wells which present no specifwill permit transmissionof thesa data to a remote pumpiug problems. Another application requiremmonitoring point. relates to the various restrictionson the surfinstallationwhich apply to many producing fieldsWell Equipment High Temperature

Tha low profile installationof the pumpingunit requires a replacement for the conventional In thermal recovery operation, artificetuffing box. This wellhead seal aqsembly Is lift equipmant capable of withstanding the hiachemctically illustrh:.eh in Figure 2. It ia operating temperature must be selected. Coin ailed on the wellhead and extends approximately venttonal rod pumping systemshave generallybeforty feet into the well. The tubing string is found successful in these applications,requirsuspended on the outer jacket of this aasembly. only replacement of stuffingbox packing with hiThe sucker rod atring is attached to the polished temperatureelements.rod in the assembly. The LIFTRONIC stuffingbox configuration

A dual seal arrangementia used to provide con8tderably changed,as descr5bed above, and woureliable containmentof well fluidswithin the flow be the moat critical element for high temperatstream. A stationaryseal at the lower end of t he operation. One installation of this system Isassembly packs-off against the travelingpol%shed operation on a steam cycledwell in Western Canarod. A traveling seal is carried on the piston After curing an initial problem of inc~~tablwhich connects the polished rod to the well-side materials, the subsurface stuffing hchain, and seals in a polished tube. Both scale are performed without problem at operating and steamspring-loaded and self-adjusting for eealing temperature. The high temperaturepacking usedreliability. Automatic purging of any leakage rated to tolerate the 600F injected stabove the stationary saal ia accomplishedby the temperature.atroktng piston to contain leakagewithtn the flowstream. i?luid flow from the tubing moves up the This well is equippedwith a poltshedannular area between the polished tube and outerjacket to the flow line connection. blowout preventer(BOP). The rame close on a emospool locatad between the well-side chain atraveling piston in the wellhead seal assembConventional steal or fiberglass sucker Thts permits manual shut-inwith the rod stringrods may be used. API insert or tubing type pumps the extreme upstroke position. A mandrel tare adaptable to the long stroke application,or hanger for the wellhead seal assembly Is beepecial configuration or accessor%eamay be used developed to permit pulling the well throto achieve mximum pump performance. tiuitableBOP equipment.

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4 A ROD PUMPING SYSTEM FOR CALIFORNIA LIFT REQUIREMENTS SPE 1

Heavy OilSucker rod pumping of unheated heavy oilmay be hampered by an inadequaterate of rod fallon the downstoke, and incompletepump fillingonthe upstroke. A reduced cycle rate haa been themost common means of dealingwith the problem ofrod fall. This mey also contributeto improvedpumpfilling.The etroking motion of the LIFTRONICpumping unit appaara to be well suited to thisapplication. In thie deeign, the unit developa anearly constant polished rod velocity throughoutthe stroke. This, in combinationwith the low cyclerate, reduces peak valocity of the rod stringaigntficantly as compared to the constantlychanging velocity and higher peak imposed by thebeam type unit. Further, the reduced valve cylcles,plus the higher compressionratio developed by thalong etroke, contribute to improved pumpdiaplacament efficiency, even in the presence ofgas or steam in the pump. An installationof thiseyetem on high water cut haavy oil productioninthe San Joaquin Valley haa demonstratedsubstantialimprovement in net oil productionas compared tothe previous baam pumping system.

Deviated WellsWear on the rod string and tubing iagenerally accelerated in rod pumping Installationson highly deviated wells. The low cycle ra


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SPE 11747 H. C. TAIT

CONCLUSIONSExperience to date with operatinginstallations of the LIFTRONIC Pumping System hasdemonstrated that performance characteriatice ofthe system are meeting the original designobjectives of the developmentproject.Measurable reductions in power consumption

have been recorded. Production records indicateimproved downhole pumping performance in t3t@SS0enhanced production,unheated heavy crude and lightoil production. Installations in environmentallysensitSveareas are being considered.

Additional operatingexperienceIs requiredto further verify these results and to more fullyevaluate long-term raliabllityand service life ofthe equipment in the system.

The performance and installationbenefttsof the LIFTRONIC system appear to warrant furtherevaluationby Callforntaoperatore.

REFERENCES1. Moore, S. D.: Well Servicing ExpendituresTThe $4-Billion Mark, PETROLEUM ENGINEEINTERNATIONAL,(July,1982) 29-36.2. Tait, R. C., and Hamilton, R. M.: A Rod PumpSystem To Reduce Lifting Costs, paper SpE 1preeented at SPE Production OperatSymposium, Oklahoma City, Feb. 27-Mar. 1, 19

TABLE 1LIFTRONIC SPECIFICATIONSMODEL A12-360

PUMPING UNITMAXIMUM POLISHED ROD LOAD LBNOMINAL STROKE LENGTE INPUMPING SPEED RANGE SPMGEAR REDUCERMOTOROVERALL HEIGHT INSTALLED INWEIGHT LE

COUNTERWEIGHTASSEMSLYMAXIMUM COUNTERBALANCEEFFECT LECOUNTERWEIGHTCASING DEPTH FTCOUNTERWEIGHT CASING DIAMETER INSPACING FROM WELLHEAD FT

12000360105 - 3*5DOUBLEREDUCTION PLANETARYNEMAB HIGH EFFICIENCY, 460VAC,THREE PHASE863s00

900050244

SEAL ASSEMSLYOVERALL LENGTHOUTSIDE DIAMETERPOLISHED ROD DIAMETHRPACKINGMARIMUNTEMPERATURE

STANDARDOPTIONAL

MAXIMUMPRESSURE

FT 40IN 4.625IN 1.5KEVLAR SELF ADJUSTING

F 25 0F 65 0PSI 700

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TABLE 2NOMINALPUMPDISPLACBMSNT*AND DEPTHLYMIT

PUHPBORE PUMPINGSPEED(SPM)(IN) 1.s 2.0 2.5 3*O 3.s( DISP?MEMENT6~BPD )1.25 98 130 196 2281.50 140 1S6 233 2s0 3261.75 193 257 321 3S6 4502.00 251 334 41s 502 5852.25 318 424 530 636 7422.50 393 524 655 7S6 9172.7S 475 633 792 950 11083.25 665 886 1108 1330 15503.75 885 1180 1475 1770 2065

~ AT 100%DISPLACBMBNTEFFICIENCY.NOTB:API66 ROD STR2NG1.257SRU2.75PUMPBORE.API 76ROD STRING 3.25TliRU3.75PUMPBORE.TABLE 3

PERFORMANCECOMPARISONWSLLABEAHUNIT

C-456D-265-120LIFTRONICA12-360

DEPTS(FT.)

600053504750420037503300295027001750

TABLE 4PERFORMANCECOMPARISON

HELLB%SAMUNIT

C-228-213-120CONDITIONSPUHP DEPTSPm BOREROD STRLHGSTRORELENGTSPUMPINGSPEEDMOTORSIZE

PERFOWCEAVG PRODUCTIONAVG OIL PRODUCTIONAVt3POHERCONSUMPTIONPOWERCOSTPERBARR2L

DYNAMONETZRCARD

w

42651-314API 7612011 SPM25SP

358BPD-o-1031RWB/BBL.l14$/BBL

BEAMUNIT

4218*,LAPI 763602.9SPM25BP

427BPD1S BPD.97KU8/BBL.084$/BBL

CONDITIONSPUMP DEPTE 2230PUMP BORE 2-1/4ROD STRING API 66STRORELENGTH 120PUMPINGSPEED 13.5s P h lMOTORSIZE 40EP

PERFORMANCEAVG PRODUCTION 790BEDAVG OILPRODUCTION 9 BPDAVG POWERCONSUMPTION ,454KWE/BBLPONSRCOSTPER BARREL .040GrBBL

*

LIPTRONICA12-360

23582-3/4Am 663603.1SPM25BP

840BPD19 BPD.360SHS/B.031$IBBL

DYNAMOMETERCARD


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A Rod Pumping System for California Lift Requirements

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