A Rod Pumping System for California Lift Requirements

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  • 8/7/2019 A Rod Pumping System for California Lift Requirements



    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.


  • 8/7/2019 A Rod Pumping System for California Lift Requirements



    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.


  • 8/7/2019 A Rod Pumping System for California Lift Requirements


    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 functiona