Leading The Way In Rod Pump Technology The petroleum industry is dominated by rod pumping. Low downhole

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2 Leading The Way In Rod Pump Technology The petroleum industry is dominated by rod pumping. Low downhole maintenance costs and long term reliability make rod pumps the world s primary choice for artificial lift. Ultra-long stroke pumping units have recently emerged as the newest improvement in rod pump technology. They afford higher effeciencies and lifting capacities, as well as reduced downhole wear and fatigue. Ultra-long stroke hydraulic rod pumping units offer unparalleled advantages over their mechanical counterparts, such as lower capital costs and greater flexibility. Hydraulic Rod Pumps, International (HRPI) leads this industry with a selection of reliable, full-featured ultra-long stroke pumping units. Ultra-long stroke above ground cylinder, with no stuffing box 2

3 Long-stroke subsurface hydraulic cylinders installed below grade (above) in Beverly Hills, California, operated by dual well power units (opposite page). Cutaway of API bolt type flange subsurface well head (left). Leading The Way In Cylinder Design HRPI combines sound engineering principals with innovative concepts to develop cylinder designs capable of adapting to virtually any application. A wide range of cylinder sizes and styles gives you more flexibility with higher lifting capacities, longer stroke lengths, lower profiles and reduced capital costs. A residential developer in Long Beach, California chose a dual-well hydraulic power unit (above) to operate two low profile subsurface hydraulic cylinders, providing unobstructed ocean views for a new housing project. 3

4 Torch Operating Company pumps highly deviated wells with dual well power units and long stroke subsurface cylinders. Leading The Way In Flexibility HRPI delivers ultra-long stroke rod pumping benefits to areas where it was previously impractical or impossible. By combining different power units with various cylinder and well-head styles, we offer several proven solutions to fit your unique application. Ultra-long stroke (above ground or low profile) hydraulic cylinders, single or dual-well power units, nitrogen counter-balanced power units and computer control afford incomparable versatility. Leading edge software provides unmatched power and flexibility, giving you more control over your producing fields. Low-profile cylinders and power units allow rod pumping in height restricted locations. 4

5 Leading The Way In Efficiency A commitment to research and development is the heart of our mission. HRPI sets new standards in electrical savings, equipment longevity, manpower efficiency and return on capital investment. Field proven equipment delivers excellent run-time performance to keep your field operating efficeintly. Single-well nitrogen counter-balanced power units (left) cut electricity bills by as much as 30% when compared to convential beam units. Dual well power units (above) offer electrical efficiencies similar to conventional beam units while maximizing return on capital investments. 5

6 Rugged on-board operator interface terminals (left) allow operators access to vital system parameters such as strokes per minute, stroke length, hydraulic pressure and pumping status. Multiple security levels help prevent un-authorized personnel from tampering with pumping conditions.the operator interface terminal provides field personnel access to all rudimentary system parameters. For advanced program features, Windows software (see below) is provided with each unit at no extra cost. Remotely accessing pumping units can be done from virtually anywhere in the world. Windows 95 and Windows CE platforms are both fully supported, offering users a wide range of interface tools. Cellular and radio modems, satellite telephones and hard-wire telephone lines can be used in any combination, including multi-drop networks. Leading The Way In Computer Technology Advanced computer programs monitor each system to keep them running smoothly, even under adverse conditions. Sticking pumps, pounding fluid, gas lock and even rod parts are all handled by our highly refined software package. HYDRAULIC ROD PUMPS exclusive ESCORT software (above) guides you through the system. The intuitive user interface keeps you current on operating conditions and allows you to access and control the system via remote telemetry... From anywhere in the world. Rugged programmable logic controllers (right) manage complicated tasks with an emphasis towards safety, efficiency and longevity of equipment. 6

7 Leading The Way In Quality Every detail is taken into consideration throughout the design process. All systems are engineered for maximum reliability. The end result is a rugged, compact, powerful pumping unit built to perform. All equipment is assembled and tested in house under strict quality control guidelines. Only components that have passed demanding field tests are used. This assures that your equipment performs properly the first time, all the time. 7

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9 Introduction: Hydraulic Rod Pumps, International (HRPI) manufactures several types of hydraulically actuated sucker rod pumping units for use on oil and gas wells. The most common type of HRP (Hydraulic Rod Pump) currently used throughout the world is an above-ground type, with a tower-mounted hydraulic cylinder (typically possessing a 120 stroke length), and is actuated with a non-counterbalanced power unit. For purposes of this discussion, the following associations are made between the stroke length of the unit and the category of pumping unit; short stroke=120, long stroke=240 and ultra-long stroke=336. While HRPI offers a broad spectrum of pumping unit solutions, this discussion is focused only on comparing the differences between long (or ultra-long) stroke HRP units and short stroke and walking beam pumping units. Overview of Long and Ultra-Long Stroke HRP Technology and it s Advantages: Rod pump technology has evolved only slightly in the last three decades with one exception: Long stroke and ultra-long stroke HRP pumping units. The necessity to maximize economical efficiencies of rod-pumped oil and gas wells has created a high demand for longer stroke lengths, as most other elements of the rod-pumped well present little room for improvement. The benefits of long and ultra-long stroke pumping units includes increased production rates, reduced bottomhole equipment wear, decreased rod string fatigue, minimized tubing wear in both vertical and directional wells and lower occurrences of bottomhole pump gas locking. These benefits are discussed below in an overview of applied long stroke and ultra-long stroke pumping technology. Technology Background: The vast majority of oil & gas wells in the world are pumped with sucker rods and plunger-type bottomhole pumps. Most employ the use of a mechanical drive beam pumping unit, which includes an eccentric crank and crank arms to deliver smooth acceleration & deceleration during stroke reversals. This affords a smooth power delivery while converting rotary motion to linear stroking motion, actuating the bottomhole pump. Most bottomhole pumps lift the produced fluid during the upstroke and reload the pump barrel during the downstroke, which creates a wide load differential when comparing the upstroke to the downstroke. Heavy counterbalance weights are used not only to overcome the weight of the rod string but also to even out the load differential, creating a more even power demand throughout the entire pumping cycle. Higher Efficiencies with Longer Stroke Lengths: Long stroke and ultra-long stroke HRP pumping units perform with higher volumetric pump efficiencies than shorter stroke length pumping units, due to the surface stroke length to rod stretch ratio. This advantage applies to the total amount of stretch caused by the load differentials (between minimum and maximum polished rod loads), which occurs as a result of lifting the plunger and the weight of the rod string. When the upstroke begins, the rod string stretches before the bottomhole plunger begins to lift fluid, which results in a loss of the gross stroke length (measured at surface). The rod string then contracts during the downstroke (when the plunger/fluid load is absent) and re-stretches with each upstroke. The length of this stretch divided by the gross stroke length is the loss of efficiency in a calculated straight percentage. For example, a pumping unit with a 120 stroke length actuates a rod string that stretches 12 each time it upstrokes loses 10% efficiency due to stretch. Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved

10 To compare using a longer stroke length on the same well, a 240 stroke unit lifts the identical rod string and plunger load. The rod string still stretches 12 every time it is loaded during the upstroke. The longer stroke unit delivers twice the stroke length (240 at surface). This equates to a 5% efficiency loss (when compared to using a 120 stroke length), attributable only to rod string stretch. The rod stretch related loss of efficiency becomes increasingly greater on deeper wells, wells with large pump plungers and wells that have rod stretch as a result of rod and tubing friction (such as directional wells). In summary, the longer stroke pumping unit can deliver 5% more production with the same inches per minute traveling speed as the short stroke unit, by spending more time lifting the plunger, as opposed to stretching the rod string. Reducing Bottomhole Equipment Wear Referring to the above comparative example, the longer stroke HRP pumping unit is slowed to onehalf the number of cycles (strokes) per minute, to produce the same volume as the shorter (120 ) stroke unit. With the well now running at one-half the SPM (strokes per minute), the traveling and standing valves in the bottomhole pump are now cycled only half as often as before. The valves in a bottomhole pump are often the primary cause of pulling jobs due to low pump efficiency, attributable to cyclical wear. These types of failures are largely relative to the number of cycles, as opposed to the amount of fluid pumped. This is due to the type of valves deployed in pumps, which are subjected to a metal-to-metal impact each and every time the valves close. By reducing the number of cycles per minute by 50%, the pump life expectancy is theoretically doubled by using the long stroke unit. Reducing Rod String Fatigue Despite delivering smooth power to the rod string during reversals, the mechanical beam pumping unit s sinusoidal acceleration and deceleration causes unwarranted fatigue on the rod string. The acceleration during the beginning of the downstroke on a beam pumping unit often drops the upper portion of the rod string downward faster than the middle or lower rod string will fall, causing rod string compression. This can be caused by a number reasons, including (but not limited to); Fluid resistance against the plunger (from fluid viscosity or gas locking). Rod friction (caused by lateral side loading of the rods against the tubing). Hydraulic resistance of fluid passing around rod couplings and rod guides. Attempting to downstroke faster than the rods will fall in fluid. Conversely, the acceleration during the beginning of the upstroke causes higher than ideal peak stresses on the rod string by quickly accelerating a mass (the rod string). In addition, it has been documented that tremendous peak stresses directly above the pump (at the bottom of the rod string) can also be much greater than predicted and/or expected from the surface when larger bottomhole pump sizes are used. This is caused by resistance against the plunger imposed by fluid friction (attempting to accelerate around rod couplings) during the acceleration phase of the upstroke, and often leads to unexplained or misdiagnosed rod body failures above the pump. These abnormal loads imposed on the rod string typically manifest themselves in the form of measurable dynamic waveforms, and appear (in graphical form) as a sine wave component within a dynamometer card. It is often referred to as the rubber-band effect, as it is based on a rod string s modulus of elasticity and can be described as a weight hanging on rubber-band (where the rod string and plunger comprise the weight and the rod string is the rubber-band). The energy created by the abnormal loads repeatedly stretches and contracts (diminishing in magnitude with each cycle) until the energy is dissipated. Rod string fatigue and subsequent premature failure occurs when the rod string is loaded and unloaded cyclically under abnormal (or extreme) loads. The predicted metallurgical life expectancy of a sucker rod string is based on the absence of compression loads (as well as other detrimental environmental factors) and is theoretically infinite providing safe Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved

11 tension loads are not exceeded (according to the modified Goodman diagram). Whenever abnormal outside forces are introduced (such as compression, corrosion or stress risers), the modified Goodman diagram no longer applies (as the results become unpredictable) and rod string life expectancy is cut drastically shorter. The imposition of abnormal dynamic loads generated by accelerating and decelerating the rod string can drastically decrease the life expectancy of rod strings by exceeding the safe metallurgical load limits under tension (during the upstroke) or compression (during the downstroke). The negative effects of these adverse loads are also magnified when operating in hostile conditions. Varying pump loads (due to fluid level fluctuations), fluid viscosity changes, well bore deviations, sudden speed changes (such as sticking pumps), temperature changes, the presence of corrosives, the fluctuating presence of gas, tubing movement, etc. all serve to adversely affect the metallurgical stability and life expectancy of sucker rods. Long stroke and ultra-long stroke HRP pumping units were conceived out of a clear understanding of current beam unit and rod string dynamics (and drawbacks), as well as what ideal dynamics for rod and tubing strings should be like. Long stroke hydraulic and mechanical pumping units (such as the Rotoflex) have the same designated purpose: To provide longer, smoother, strokes with linear traveling speeds. Linear traveling speeds drastically reduce the dynamic wave-form load conditions (rubber-band effect) by accelerating to a slower fixed rate and holding a constant rate for the majority of the stroke. This reduces the magnitude of the momentumreversal-generated energy and allows it to dissipate quickly, drastically reducing rod compression and acceleration-generated higher stresses. Minimizing Rod and Tubing Wear Rod compression causes several different problems, one of which is rod fatigue and subsequent premature failure. The second problem is two-fold: Rod and tubing wear. Most cases of rod string compression cause the rods to buckle inside the tubing. This lateral movement creates unnecessary contact between the rods and tubing, which results in tubing and rod wear. Tubing wear is often more prominent (and more costly to repair) because it results in tubing string pressure failures (splits). Rod body wear is often overlooked as an indicator of possible string compression and is usually not properly evaluated during a workover unless extreme wear is present. The worn condition is also commonly dismissed as acceptable wear since the lower portion of the rod string is less likely to fail (where rods are not subjected to high stresses). The effects of rod string compression are expensive and unnecessary, and can be greatly reduced when long stroke units are utilized. Long stroke and ultra-long stroke HRP pumping units reduce rod and tubing wear by two methods. The first is explained above, by reducing acceleration and maximum speeds, and by using a fixed traveling speed. The second is by distributing wear patterns over larger areas (or longer distances). Most rod strings are screwed together with rod couplings. The coupling has a higher profile (larger OD) than the rod body, which forces it to contact the tubing before the body of the rod makes contact. This forces any side loads to be distributed with a high concentration of force on a very small area (the length of the coupling only). This concentrated lateral force travels up and down the tubing only the distance of the stroke length, creating a wear pattern inside the tubing string. The longer the stroke length, the larger the area (or longer linear distance) the wear pattern can be distributed. With a 120 stroke length and rod couplings evenly spaced every 30 feet, the tubing experiences only a 120 long wear pattern from the coupling traveling inside. This leaves 240 of unswept distance in the tubing, or 66.6% of the tubing unworn by coupling contact. A long stroke unit (240 ) will effectively distribute the wear over twice the area (distance), leaving only 33.3% of the tubing unworn. This wear pattern enhancement greatly extends the life of the tubing, reducing costly tubing string failures. Reduced Gas Locking Problems Gas locking occurs when the traveling valve (inside the bottomhole plunger) fails to open to reload the pump, due to the absence (or deficiency) of fluid below the plunger (in the pump barrel). The traveling Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved

12 valve relies on the presence of fluid below the plunger to provide pressure during the downstroke to force the valve open. Wells that produce moderate to high concentrations of gas (or liquids able to form gas under low pressures) are likely to have gas-locking problems. This includes steam flood, CO2 flood and wells that operate at or near a pumped-off condition. Gas locking can be reduced by spacing the pump plunger close to tapping down with each stroke (a condition where the plunger mechanically hits the bottom of stroke) however, this does not eliminate it or prevent it. The practice of spacing pumps very close to tapping down creates a higher likelihood of damaging either the bottomhole pump, pump shoe (seating ring), standing valve, or standing valve retrieval (on-off) tool. In addition, the practice of tapping a pump down can severely damage to the rod string due to the extreme state of compression. Spacing a plunger close to tap down is done to reduce the un-swept area below the plunger, effectively increasing the pump s compression ratio. The compression ratio of a pump dictates how much pressure can be built up below the plunger to assist in opening the traveling valve. Longer strokes and larger pump diameters also increase the pump compression ratios and help to reduce gas-locking problems. Long and ultra-long stroke pumping units help increase well productivity by reducing the frequency and likelihood of gas locking, thereby helping wells remain pumped down longer (reducing annulus back pressure against the formation). Summary: The benefits of long and ultra-long stroke HRP units have only been briefly discussed here and have focused solely on the downhole aspects for operational comparisons. Long and ultra-long stroke HRP units provide substantial long-term cost savings (as compared to short-stroke hydraulic and beam pumping units), by actuating the rods in a manner close to the ideal model for sucker rod pumping dynamics. Long stroke and ultra-long stroke HRP units can deliver superior efficiencies, reduced rod and tubing wear, longer bottomhole pump runs and higher production rates than short stroke hydraulic and beam pumping units. Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved

13 Direct Mounted HRP Cylinders Direct mounted above ground cylinders are the simplest and most cost-effective models of all HRP type cylinders. Standard size models offer peak polished rod load capacities from 12,364 to 42,390 pounds, with stroke lengths up to 336 inches. These cylinders are mounted directly to the wellhead, which eliminates the stuffing box. PPRL Cylinder Load Capacities 45,000 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5, Hydraulic Pressure The cylinder includes an integral polished rod, with a double-sided (back-to-back) high-pressure seal section. Cylinders are rated for operating pressures on the hydraulic side of up to 5,000 psig and 2,500 psig on the production string. Installation typically requires no changes to the well head, no special tools, and only minimal ancillary equipment. Handling and installation time is similar to that of a beam unit, where make up of the bridle, horse head, carrier bar, clamp and stuffing box are replaced. Bottomhole pumps are spaced with pony rods (if necessary). To install, the assembly is picked up, attached to the rod string, extended (stretched), lowered into place and the lower cylinder head is tightened onto the pumping tee Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved.

14 Subsurface HRP Cylinders Subsurface cylinders are designed to fit inside the well casing, eliminating overhead clearance requirements. These cylinders install inside the tubing string and remain submerged in the production fluids while operating. Standard size models offer peak polished rod load capacities from 12,364 to 42,390 pounds, with stroke lengths up to 336 inches. These cylinders are mounted inside the wellhead, which eliminates the stuffing box. PPRL Cylinder Load Capacities 45,000 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5, Hydraulic Pressure The cylinder includes an integral polished rod, with a double-sided (back-to-back) high-pressure seal section. Cylinders are rated for operating pressures on the hydraulic side of up to 5,000 psig and 2,500 psig on the production string. Unbalanced external cylinder collapse ratings are a minimum 1,500 psig, and up to 5,000 psig (while pressure balanced internally). Installation requires minor modification of the wellhead. Required ancillary equipment includes special custom "made to order" flanges, lifting tools / crossovers and a single casing joint. Continued on page 2 Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved.

15 continued from page 1 Handling and installation time is slightly more than that of a beam unit, where make up of the bridle, horse head, carrier bar, clamp and stuffing box are eliminated. Installation: The tubing string is landed on the existing wellhead flange with a single joint of casing at surface, crossed over to the tubing string (at the bottom end). Prior to installation, a new double thick API bolt type flange is threaded onto the casing joint (at the top). A crossover / lifting tool is threaded into the top of the double thick flange, and the entire assembly is picked up, attached to the tubing string and lowered into place. This new double thick tubing landing flange (with casing joint) is then secured to the wellhead. The lifting crossover remains installed when a rod table, rod BOP and/or pumping tee are used. The bottomhole pump is run in the hole through the new double thick flange and casing joint, along with the rod string. The well is then spaced with pony rods. The lifting crossover / rod table assembly is also removed from the wellhead while the bottomhole pump is being spaced. A flange is then installed on the upper cylinder head and the cylinder assembly is picked up in collapsed state, attached to the rod string, raised (extended or stretched) and lowered into place. Insert pumps can be stabbed into the pump shoe (seating ring) by lowering the cylinder assembly below the hang-on point. This is accomplished by un-threading the cylinder flange (upwardly), or leaving the flange loose before the cylinder is picked up. The cylinder-to-flange thread connection is a tapered casing thread, threaded from the top (larger end of taper at the bottom). The cylinder is then lowered through the casing joint (below the hang-on point), while the cylinder flange rests on the double thick tubing flange. Removal of the cylinder from the wellhead requires unseating insert pumps or pulling tubing style plungers out of (or above) the pump barrel. When the plunger diameter is larger than the tubing ID, an oversized tubing joint is required above the pump barrel to allow pulling the plunger out of (above) the barrel. Design Considerations: Use of these cylinders requires ample clearance between the outside diameter of the single joint of casing (oversized production tubing string joint), and the inside diameter of the existing casing (annulus). A minimum clearance of.125" should be used, to provide ample installation clearance, as well as clearance for casing gas and/or liquid flow. The following chart outlines recommended minimum casing sizes for evaluating subsurface cylinder installations. Cylinder Surface Joint Existing Casing* Diameter (Tubing String) (Annulus) /2" - 9.5# 5-1/2" - 23# /2" - 17# 7" - 23# /8" - 24# 8-5/8" - 49# 4.0 7" - 38# 8-5/8" - 36# /8" - 39# 9-5/8" - 47# *Existing casing, minimum ID or equivalent Tubing and rod rotation: Tubing rotators are available through our alliance partner (RPS Canada) for all sizes and styles of wellheads, including subsurface cylinders. Rod rotators are not available or compatible with direct mounted or subsurface HRPI cylinders however, all of our hydraulic cylinders allow the rod string to freely rotate within the tubing string. This is a product of the piston resting on hydraulic fluid (while suspended by pressure). When tubing rotators are combined with any type of HRPI cylinder, the tubing string can deliver friction-induced torque to the rod string, especially in deviated or directional wells. This same rotary torque can be harnessed and used to positively rotate the rod string (as well as the cylinder's piston and the integral polished rod) by using a free-sliding linear guide inside the tubing string, which guarantees the rods are being rotated at the same speed as the tubing. Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved.

16 Single & Dual Well Power Units (non-counterbalanced) HRPI non-counterbalanced power units are designed to deliver reliable hydraulic power to the wellhead in a very cost-effective package. Designed with the ability to power two wells with one electric motor, they provide more work for the investment than all other HRP power units in the industry. Non-counterbalanced power units convert electrical energy into linear motion, with no energy recovery or load counterbalancing means. Flow schematic: Hydraulic oil is drawn from an atmospheric reservoir, then pressurized up to (demand-sensitive) operating pressures and directed to the wellhead cylinder by a three-position, four-way (four-port) directional control valve. The oil pressure (and flow) lift the piston and the attached polished rod load. When the piston has reached a desired point during the upstroke, the directional control valve re-directs the pump and cylinder flow back to the reservoir. The hydraulic cylinder s return flow rate is controlled by an adjustable throttle valve. This throttle valve is only effective during the downstroke, as a check valve is installed in parallel with the throttle valve, allowing fluid to bypass the throttle unrestricted during the upstroke. Upstroke flow rate is governed only by the hydraulic pump displacement, which can be configured either as a fixed displacement or variable displacement type pump. All hydraulic systems include integrated cooling and return flow filtration to keep the hydraulic oil within safe operating temperature ranges, and to keep the oil clean. Single vs. Dual: The single well configuration is a dual well power unit, operating in single well mode. Dual well operation is accomplished by alternately stroking each well, so that both wells remain out of phase. One well strokes upward while the other well strokes downward. Independent strokes per minute rates are achieved by ratio cycling, which is managed by the on-board PLC (Programmable Logic Controller). Other considerations: Non-counterbalanced power units are typically not compatible with internal combustion engine prime movers, due to the heavy cyclic load fluctuations imposed by a powered upstroke. Each hydraulic power unit is sized for each individual application. When properly designed, it affords excess capability for speed increases to help accommodate changing well conditions and operator demands. Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved.

17 Single Well Power Units (nitrogen-counterbalanced) Overview: HRPI nitrogen-counterbalanced power units are designed to deliver reliable hydraulic power to the wellhead in a very energy efficient package. Designed to power one well with one electric motor, they provide higher electrical efficiencies than beam units and other HRP power units. Nitrogen-counterbalanced power units convert electrical energy into linear motion, with a load counterbalancing nitrogen-gas spring (accumulator). Flow schematic: Hydraulic oil is drawn from an atmospheric reservoir, then pressurized up to (demand-sensitive) operating pressures and directed to the wellhead cylinder by a directional control valve. The oil pressure then lifts the piston and the attached polished rod load. A hydraulic motor is also close-coupled to the pump, which consumes nitrogen-pressurized oil. The nitrogenpowered oil assists the pump (via the hydraulic motor), which reduces the net horsepower required to lift the cylinder load. A small displacement hydraulic pump is also close coupled to the larger pump and motor, which pre-charges the accumulator with oil at startup and momentarily during normal operation to replenish any oil lost though hydraulic motor and cylinder piston ring leakage. When the piston has reached the desired endpoint during the upstroke, the directional control valve directs the pump flow to the accumulator, which recharges the accumulator. The hydraulic motor is driven by the oil in the cylinder (during the downstroke), which reduces the horsepower required to re-charge the accumulator with the large pump. The oil returning from the hydraulic cylinder at the wellhead is flow controlled by two devices: The pressure-load on the large pump (recharging the accumulator during this phase) and the electric motor s resistance against overrunning (RPM) together prevent the cylinder from falling at an uncontrolled rate. All hydraulic systems include integrated cooling and return flow filtration to keep the hydraulic oil within safe operating temperature ranges, and to keep the oil clean. The circuit design of the nitrogencounterbalanced system precludes dual well configurations, as the motor, pump(s) and accumulator are all under constant use. Strokes per minute rates are managed by the on-board PLC Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved.

18 (Programmable Logic Controller). Other considerations: Nitrogen-counterbalanced power units are compatible with internal combustion engine prime movers, due to the stable load fluctuations of the balanced up and down stroke. Every hydraulic power unit is sized for each individual application. When properly designed, it affords excess capability for speed increases to help accommodate changing well conditions and operator demands. Safety Functions: In addition to monitoring pressures, temperature, amperage and oil levels, several hydromechanical devices are integrated to protect personnel and the hydraulic system. This includes automatic shut-off valves on the accumulator and cylinder, as well as well automatic system bleeddown valves. Nitrogen Storage: HRPI began developing nitrogen-powered systems in 1987 and has leveraged that experience in designing a trouble-free nitrogen- counterbalance system. While all nitrogen-charged accumulators consume nitrogen at some level, we designed our system with ample storage capacities and flexible manifold circuitry to allow manual or automated adjustment of system pressures on the fly, without using an off-line charge bottles. up and downstroke speeds (fixed). When deploying HRPI pumping units in highly deviated wells, heavy crude oil, or wells with rod string compression, it is best to use the variable displacement model so that the rod string can be lowered more slowly than the upstroke speed. While this practice consumes more electrical energy, it affords other cost-saving advantages that may outweigh the added electrical costs. For most applications however, fixed displacement models provide a more attractive price range and more than satisfactory results, especially when comparing a beam unit with the ultra-long stroke length and the higher efficiency nitrogen counterbalanced unit. Variable and Fixed Speed Models: Nitrogen-counterbalanced power units are available in two different configurations: Variable displacement and fixed displacement. The distinct difference between the two different models is the ability to independently adjust the upstroke speed and the downstroke speed (variable), and matched Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved.

19 Overview: Programmable Logic Controller with Palmtop PC All HRPI power units are PLC Controlled, to afford excellent reliability, flexibility, and automation. PLC (programmable logic controller) automation is used to manage stroke time (length and position) and stroke frequencies (SPM), as well as provide several levels of safety protection. Extended features include generating hydraulic dynamometer surface cards, automatic pump-off control, extensive on-board data storage, remote telemetry and control or SCADA communication. Stroke Timing and SPM: Hydraulic cylinders (installed on the well head) require delivery of consistent and predictable stroke times (length and position), to deliver consistent actuation to the sucker rod string. The PLC delivers precision, consistent control timing to the directional control valve(s), which govern hydraulic flow patterns. Reliable stroke per minute pumping speeds are also required, to ensure stable production rates. The PLC automatically calculates SPM timing and stroke ratios (for dual well power units), based on user settings. This also creates a very simplified user interface, and speeds the process of tuning and adjusting the power unit. Stroke position can also be freely adjusted, in percentages (of a full stroke), or inch unit increments. Stroke position is also controlled and adjusted by selecting the upper or lower portion of the available stroke, in combination with the stroke length. The PLC also makes use of solid-state electronic pressure transmitters to confirm and automatically adjust the user selected stroke timer settings, to adapt to changing well conditions and hydraulic system efficiencies. Surface Hydraulic Dynamometer Cards: The PLC also includes the ability to generate surface dynamometer cards, based on hydraulic cylinder loads. While not as accurate as conventional load cell measurement, it is an invaluable trend analysis tool to assist in the optimization process. The proprietary file format includes vital hydraulic system data, which can be automatically filtered out and exported for use with most other analysis software. Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved.

20 Automatic Pump-Off Controller: The PLC also includes an automatic pumpoff controller, which compares the current dynamometer pressure data against a user-selected (and stored) sample. Slight variations in pressure data trends are also accommodated with a user defined variant factor (in percentage). This provides a reliable method of monitoring pumping conditions, while allowing for small fluctuations in changing well and hydraulic system conditions. Operator Interface Terminal Safety Functions: In addition to providing the dynamometer cards, the PLC uses continuous pressure monitoring to protect personnel and the hydraulic system, as well as bottomhole equipment. A two-tiered hydraulic pressure level setting scheme is used to provide stroke interruption (during the upstroke), and immediate system shutdown if the directional control system should malfunction. The electronic shutdown safety functions serve to complement the mechanical pressure safety valves on the hydraulic system. Supported Platforms: HRP Escort is designed for Windows 32 bit operating systems, such as 95, 98, and Windows NT. Windows CE is also supported with a scaled-down version (HRP Escort Jr.). File Management: HRP Escort provides several key features, such as exporting the dynamometer files and system log, for evaluating overall performance over long term. The proprietary dynamometer and hydraulic system data file is designed for multiple sequential samples in a single file, which are organized in chronological order. Users can easily scan or step through the samples, or jump to specific date samples. Other Key Software Features: The proprietary data and log files include many hydraulic system data points, as well as an historical listing of which users have changed key system parameters. This provides the ability to view historical speed changes (including who and when), and how the well the hydraulic system has performed over time. Downtime is also historically tracked to assist in diagnosing loss of production or to monitor field maintenance problems. Operator Interface Terminal: The optional OIT (Operator Interface) Terminal allows field personnel to monitor and/or adjust hydraulic system settings at the power unit, for cursory maintenance. Password levels are used to protect unauthorized users from changing system settings. Access to vital system settings for monitoring (unprotected access) or adjusting basic hydraulic system parameters (password required) and maintenance tasks (level 3 password) are accommodated. The more advanced graphic and data features provided by HRP ESCORT Software are not available with the OIT, as a GUI based operating system are required and are not possible with the text-based OIT. Copyright 2000, Hydraulic Rod Pumps, International. All rights reserved.