1

CHAPTER 1

Introduction

Artificial lift refers to a method that are used in hydrocarbon wells to increase the production rate

which is more that the rate that could be obtained by natural flow through the utilization of the

reservoir pressure alone. Besides that, artificial lift is also can be used when the natural drive is

not strong enough to push the hydrocarbon to the surface and are not considered economic. This

systems are designed to provide the energy to move the fluids from the bottom of the well to the

surface at a desired rate and delivery pressure. This energy support the flowing pressure available

at the bottom of the well that depends on the productivity of the reservoir.

Basically, artificial lift can be categorize into two main group which are pumping systems

and gas lifts. Both has its own purpose and advantages. Most oil fields require some type of

artificial lift at some point in time. When the gas in reservoir is depleting, gas lift may be a viable

lift method because it can be relatively low-cost well interventions. However, when a gas lift

system in inadequate, too expensive, or impossible to use, the artificial lift using pumping method

can be its alternative way. Before shows type of artificial lift and its system efficiency.

Type System Efficiency

Gas Lift 10% -30%

Foam Lift N/A

Plunger N/A

Rod Lift 45% – 60%

Progressive Cavity Pump (PCP) 50% – 75%

Electric Submersible Pumping (ESP) 35% – 60%

Hydraulic Jet 10% – 30%

Hydraulic Piston 45% – 55%

Source: Weatherford - Introduction to Artificial lift System. Refer to appendix for more detail.

For this report, we will focus more on progressive cavity pump. According to Weatherford

(2013), rotating-rod-driven Progressive cavity pumps (PCP) were developed in 1980s for oilfield

2

application. PCPs commonly used for viscous oil, horizontal wells and also for sand production

condition. PCPs usually been used for cold heavy-oil production because of their adaptability to

viscous and abrasive fluids. However, for thermal recovery, a standard PCP is not compatible

because the elastomer of the stator, which is the major components of the pump cannot withstand

fluid temperatures higher than 160°C. Figure 1.1 below, shows the components of Progressive

cavity pump.

The main components of this pump are stators, rotors and drive shaft. The pump consists

of a single helical which rotates inside a double helical elastomeric gear of the same minor diameter

and twice the pitch length which known as stator. The rotor rotates eccentrically inside the stator,

as it rotate it form a series of sealed cavity 180 degrees apart which progress from the suction to

the discharge ends of the pump. As one cavity diminishes another is created at the same rate due

to a constant non-pulsating flow. The total cross-sectional area of cavities remains the same

regardless of the position of the rotor in the stator.

Compared to other methods of artifical lift in similar applications, the PCPs is normally

the more efficient means of aritifical lift. It has low initial investment, easy to install and minimal

maintenance. PCP kinematics has provide major advantages for downhole pumping because its

provides continuous high-volume axial, can tolerates with very low inlet pressure as a vacuum

pump, has ability to compress gas as long as the seal between stator and rotor is maintained and

rotating with low-torque.

Figure 1.1 Progressive Cavity Pump [Source: Netzsch -

NEMO® Pump Components]

3

Chapter 2

Operational Principle of PCPs

2.1 Operational principle of Progressive Cavity Pump (PCP)

Progressive cavity pump is a type of positive displacement pump which transfer fluid by trapping

a fluid and discharging it a fairly constant volume. In general a progressive cavity pump (PCP)

works by transferring fluid that is trapped tight inside its cavity trough movement of the rotor, the

movement of the rotor force the fluid to move in a positive direction. Since the fluid that was

pumped does not changes its size and shape because of the tightly sealed cavities between the

stator and the rotor, this cause the oil to be transferred at a constant and predictable volume. Due

to this operational characteristic is why Progressive cavity pump (PCP) are suitable for a high

viscous oil.

In detail the operation of progressive cavity pump (PCP) depends on the rotor movement.

As the rotor started to rotate it will seals securely against the rubber stator which will result to a

set of fixed volume of cavities in between the rotor and the stator to form. As the rotor started to

Figure 2.1 Show a cross sectional look of a rotor and a stator

4

rotate again, the cavities moved which in turn will forces to the fluid to progressively being

displace.

According to moineaus’s rule, a contact between the stator and rotor must occur to ensure

the pump operation successfulness. Traditional progressive cavity pump (PCP) usually operates

with zero clearance (when the stator and elastomer are in contact without any space). A zero

clearance between the rotor and stator ensure no internal slips and leakage. But since there is

contact between the stator and rotor, this means that there is friction, and since there is friction it

can limit the life of the pump. According to Gamboa et al (as cited in Vector and Wirth, 1995), a

contact between the stator and the rotor are not necessary to ensure fluid movement. This means

that better material such as steel and alloy can be used as the rotor without damaging the stator.

2.2 Factors affecting the operation of progressive cavity pump

When discussing the operation principle of progressive cavity pump (PCP), it is important to know

factors that can affect the operation of the pump. The operation of the progressive cavity pump can

be disrupted due to some problems caused by the rotor and stator.

2.2.1 Rotor Operation Failure

2.2.1.1 Abrasive wear

This problem occur because the chrome plating on the rotor are worn. The worn on the

chrome plating can cause the original profile of the rotor to change. This changes can

greatly affect the performance of the pump since the interference fit between the stator and

the rotor have been changed which in turn will change the cavity profile hence affecting

the flow. For cases for some serious abrasive wear where the chrome plating has worn

down revealing the base metal underneath it, a permanent damage to the elastomer might

occur.

5

2.2.1.2 Acid attack

This type of problem occurs when the crude oil pH dropped down below six (6). In

definition acidic crude oil are crude oil that possessed a considerable amount of naphthenic

acids or other acid. These acidic crude oil can strip down the plating element on the rotor.

The rough surface rotor can damaged the elastomer which in turn affect the flow and

pressure.

2.2.1.3 Fatigue Failure

When the material undergoes cyclic stress it can cause the fatigue failure to the rotor. A

fatigue failure is like a rolling snowball, it started with a small crack which will grow due

to exposure of cyclic stress. Since the movement of the rotor is in an eccentric motion any

inappropriate Installation of the rotor can cause an extra load at some part of the rotor when

turning which in turn will increase the cyclic stress. Fatigue failure may also be caused by

any reduction in the cross-sectional area of the rotor due to damage to the rotor surface.

The reduction in surface area may increase the load at that specific point and cause an extra

load.

2.2.1.4 Pitting Corrosion

Pitting corrosion occurs when the acidic fluid starting to attack the base metal of the rotor.

This only happened when the chrome plating of the rotor have been worn out

2.2.2 Stator Operation Failure

2.2.2.1 Run Dry

When there is less fluid that is pumped through the pump, it will cause the elastomer to run

dry which will cause the elastomer to be hard and brittle

6

2.2.2.2 Hysteresis

Hysteresis is caused when the elastomer are facing overpressure. When the elastomer is

facing overpressure it can affect the flow of the fluid. When less fluid flow it can cause the

elastomer to run dry and cause overheat issues which will damaged the elastomer and in

time will cause pump failure

2.2.2.3 Gas Permeation

Gas permeation occurs when the gas enters the elastomer matrix and expands due to drop

in pressure. As the gas expand it will cause blister or bubbles to form inside the elastomer.

In some serious case the gas can expand to a point where the elastomer ruptures. This is

called explosive decompression. The pressure drop that cause the gas to enter the elastomer

can be caused by events such as when the fluid level equalizing in the wellbore right after

the wellbore are shut down or it might cause by the pulling of the pump

7

Chapter 3

Major Components of PCPs

3.1 Major Components

Like any other positive displacement pumps, progressive cavity pumps (PCP) are

engineered to displace liquid with rotary motion such as gears, screws vanes or lobes. The major

system components that make up the PCP are the downhole progressive cavity pump, sucker rods

and production tubing strings and the surface driver equipment. This section will focus more on

the major components of the downhole PC pump.

Figure 2.1 Conventional Progressing Pump (PCP) cross-section device

3.2 Downhole PC pump

In progressive cavity pumps, the component that produces this rotary motion is the screw.

Core components that make up or define the progressive cavity pumps are the rotor and the stator

followed by other essential components that make up the downhole PC pump.

8

3.2.1 Rotor

The rotor is a single threaded helical screw in shape (thus the name screw pump).

It is the moving or rotating component of the progressive cavity pump made possible by

the connected universal joint and drive shaft. Some optional designs of the rotor also

include hollow rotors which provide higher operating speeds, longer service life and silent

low-vibration option. Normally it is made out of steel (ie. Chromed plated alloy steel)

which provides resistance to abrasion and wear depending on the type of manufacturer.

3.2.2 Stator

The stator on the other hand has an internal shape of a double helix. It serves as the

stationary major component of progressive cavity pump. The stator houses the rotor and

produces the cavities needed for the displacement of fluid. The pitch length of the stator is

manufactured twice that of the rotor (ie. 1:2 profile elements, one lobe on the rotor and two

lobes in the stator). According to the inventor’s original theory, René Moineau, any

combination is possible so long as the stator has one or more lobe than the rotor. Normally

it is formed from an elastomeric material of which fits the rotor with an interference fit (ie.

Natural rubber, Buna nitrile, Viton etc.) this is also dependent on the type of manufacturer.

3.2.3 Universal joint (U-joint)

Figure 3.1 Universal Joint/ Cardan Joint

9

A universal joint is a pair of hinges connected to each other with an orientation of

90O. It is a joint or a coupling that connects 2 rigid rods together while at the same time

allowing it to “bend” in any direction (permitting some degree of misalignment) while

rotating thus introducing mechanical flexibility to the equipment. It is a connection made

between the rotor (output shaft) and the drive shaft (input shaft) of a pump. The rods are

connected by a cross shaft that transfers the power delivered by the power source to the

rotor. U-joint plays an important role in progressive cavity pumps as the rotor rotates in a

hypocloid form of motion or off-center motion (thus the alternative name eccentric screw

pump). Apart from off-center motion, the U-joint also introduces easier disconnection for

repairs or alterations thus reducing cost when damages occur.

3.2.4 Suction Casing

Suction casing houses the stator and rotor. Its main purpose is to protect the

external layer of the stator and prevents external water absorption or abrasion. The

housing is usually made from stainless steel, iron, bronze, titanium or other forms of

alloy.

3.2.5 Drive Shaft

PCPs requires torque to rotate the rotor thus a drive shaft is installed. Drive shafts

are a mechanical component used for transferring torque by connection of different

components in a drive train that cannot be connected directly due to distance or the need

for relative movement between them. At the same time, due to torque, drive shafts are

also subject to torsion and shear stress that is equivalent to the input torque and the load.

As a result, drive shafts are manufactured to be strong enough to bear heavy stress at the

same time avoiding excess additional weight as it would in turn increase inertia. Usually

drive shafts would usually incorporate one or more joints and couplings to allow

variations in the driving and driven components.

10

3.3 Sucker Rods and production tubing

Sucker rods are steel rods usually between 25 and 30 feet in length and threaded at both

ends. They are usually applied in the wellbore to join together surface and downhole components.

Usually fitted for piston type pumps in an oil well, PCP pumps also rely on sucker rods to transfer

torsional an axial loads from the surface drive system down to the bottomhole PCP. Production

tubing on the other hand are mostly the typical ones used in other oil and gas production operations.

3.4 Surface Drive Equipment

Surface drive system is essential as it delivers torque required at the rods and aids in safely

rotating the polished at the desired speed. Apart from that it prevents produced fluid from escaping

the system. The system is located safely at the surface where it is easily manageable and contained.

All surface equipment systems include a wellhead drive unit (drive head), a stuffing box,

power transmission equipment and a prime mover. Wellhead drive units facilitate proper alignment

of the drive on the wellhead which aids in preventing the stuffing box from leakages at the same

time gives enough strength to carry heavier drive heads and motors. Its main importance is to

support the axial rod-string load. Power transmission equipment on the other hand is used to

transmit power (power and speed) from a prime mover to the rod. This equipment usually consists

of a speed reduction or torque transfer system that allows a prime mover to operate at an increased

speed but at the same time lower torque than that of the rod. Lastly is the prime mover which

serves as the energy provider to driver the surface equipment and ultimately the rod string and

downhole pump.

11

Figure 3.2 Progressing Cavity Pump (PCP) system components

12

CHAPTER 4

ADVANTAGES AND DISADVANTAGES OF PCPs

4.1 Advantages

The progressive cavity pumps have some unique characteristics compared to other artificial lifts

that are used for oil field. One of the unique characteristics of this pump is their higher efficiencies

compared to other artificial lifts which is 55 to 70% efficiency. This pump is an extremely versatile

pump the can be used in many different pumping applications. Thus it can achieve higher

efficiency.

These pumps are the most beneficial pump. This pump is beneficial compared to other is

because the cost for this pump is lower compared to others. This pump is having lower capital

cost. The construction of this pump is simple. The start-up cost of this is reduced due to the

compact surface drive units of this pump. Due to lower cost and simple construction, thus more

pumps can be installed and more oil can be recovered. This makes the oil recovery percentage

become higher. Besides that, this pumps running at low cost. This is because the overall efficiency

of 70% which is significantly higher than alternative lift methods. This will reduces the cost per

barrel of the recovered fluid. If the efficiency is very low, the cost per barrel of recovered fluid

will be higher.

The simple construction consists of only one moving part downhole and has no standing

or traveling valves to block. The pump handles gas and solids without blocking and is more

resistant to abrasive wear. This progressive cavity pump is also low and unobtrusive profile of the

quiet running surface drive head makes this pump ideal for the environmentally sensitive areas.

Besides that, this pump also avoids the spills of the fluid to happen. This is done by using the art

Leak Detection Stuffing Boxes. This help to protect the environment from spills.

13

The reading of the progressive cavity pump is very accurate compared to the other types

of pumps. This is because the low pulsation the progressive cavity pump offers very exact

metering. Thus, no additional valve will be required in order to obtain the exact reading.

By using this pump, there will be no backflow into the pump. When the application stopped, the

progressive cavity pump closes like a slider. Thus, there will no backflow returns to the pump.

Since there is no backflow into the pump, the flow rate is increasing always proportional to the

speed. Thus, the optimal efficiency of this pump extends over a very wide range.

The progressive cavity pump is suitable for high pressure. This pump can achieve a

pressure increase of up to 80 bars. The higher pressures are desirable for moving product greater

distances and for applications involving extrusions.

This pump is used when the pumping application is not suited to a centrifugal pump. This is applied

especially when the liquid has a higher viscosity or higher thickness than water. This progressive

cavity pump is different with the centrifugal pumps. Centrifugal pumps become very mechanical

and volumetrically inefficient when the viscosity of liquid goes up, thus make the flow goes down

and the power consumption goes up, but this goes opposite with the progressive cavity pump. If

using the progressive cavity pump, the mechanical efficiency and volumetric efficiency goes up

when the viscosity increase, lower power and higher flow.

Therefore, this pump is ideal for liquids with higher viscosities. This pump will maintain

the same flow no matter what the viscosity of the liquid is. If there is a pumping application where

the flow of liquid need to be constant but the liquid viscosity is variable and will change, then this

pump should be used.

This pump is an ideal pump to be used when the application requires a varied flow. This pump has

a precise flow per revolution of the pump. Thus, it is easy to regulate the pump flow by just

regulating the pump speed. Nowadays, the modern pump speed controllers are well suited with

this progressive cavity pumps.

The progressive cavity pump is also suitable to be used when the suction conditions of the

pumping applications are not ideal. This pump requires much lower Net Positive Suction Head

(NPSH) as compared to a centrifugal pump. This is because the internal pump velocity is lower.

14

A progressive cavity pump can pump when the pressure as low as 28” of mercury (Hg) but the

centrifugal pump cannot. This pump is very suitable to be used with the difficult applications which

the centrifugal pump cannot be used. This pump also is easily to be filled.

This pump is also ideal for the applications where the liquid is sheer sensitive again due to

the lower internal velocity. This pump is very good to be used when pumping oil and water

mixtures to separation devices. This pump will not change the oil droplets compared to the

centrifugal pump which will emulsify the oil and make oil droplets very small. The separation

devices work much better when the oil droplets are larger. Thus, the progressive cavity pump is

very suitable for this application in order to increase or maintain the performance of the separator

devices.

Moreover, the progressive cavity pump is best applied when the liquid contains abrasive

solids. This progressive cavity pump can pump solids very well compared to other types of positive

displacement pumps which cannot pump solids very well. The other types than progressive cavity

pump cannot pump solids very well or for long is because their close tolerances and all metal

designs. Most of the centrifugal pump will simply wear out when solids are present in the liquid.

This could make them clog. This progressive cavity pump is designed to last longer than all other

pumps on abrasive applications. For the abrasive application, the pump is designed with the rotor

and stator is the heart of the pump. The internal velocity of the liquids travels through the pump is

much lower than other types of pumps

This is because the flow travels in the progressive cavity pump is different than other types

of the pumps. The flow travels axially through the progressive cavity pump and it is not travelling

around the outside of casing in a high speed circle like the flow that travel in other pumps. The

abrasive particles are flow in a parallel to the pumping surfaces at low speeds, thus not abrading

the pump. Besides that, in the progressive cavity pump consists of a rubber stator. If a particle

contact with this rubber stator, the stator has some flexibility to move and not abrade. This makes

the pump last longer than metal parts in other types of pumps on abrasive applications.

15

4.2 Disadvantages

Disadvantages Explanations

Elastomers swell in

stator

Elastomer swell happens when the stator is affected by the

production fluids or chemical reactions and temperature. When the

stator is in contact with high API gravity oil and incompatible

chemicals, the stator is said to be in chemical swell. Thermal swell

happens when the temperature increases, causing the elastomer to

expand.

Figure 1: Chemical and thermal swells

Pump stator may

undergo damage if

pumped dry

When the pump is pumped dry, the elastomer will become hard and

brittle, eventually cracked. This usually happens when lack of fluids

entering the pump; causing temperature build-up and eventually

expanding the elastomer.

Pump off control is

difficult

Pump off can be defined as the lack of fluids entering the pump. This

occurs mainly because of plugged pump intake, poor inflow or

production rates exceed the inflow.

Low pump speed Generally, the pump speed is set at most 500 RPM because speed

exceeds the maximum will cause problems to the sucker rod and

surface equipment. Such problems as fatigue failures and vibration.

Gas permeation

Gas permeation occurs when gas enters the elastomer matrix and

expands due to a pressure drop. This usually happens during pulling

16

of pump or shut down. The expanding of elastomer matrix

sometimes called as explosive decompression.

Figure 2: Explosive decompression

Short life span of

stator and rotor

Abrasive wear occurs between the stator and rotor. This usually

caused by rubbing velocity, which in time will reduce the life span

of rotor and stator. Besides that, frequent change of the stator and

rotor will increase the operating cost of the pump. Thus

Figure 3: Abrasive wear of the rotor

Limited to relative

shallw wells

The pump is limited to the shallow depth well (approximately 5000

ft. – 6000ft.) due to its limitations. Torsional or fatigue failures

placed on the rod strings and temperature limitations are some

limitations why it is not used in deeper wells.

Limited to viscous

fluids

When gas enters the pump, it will decrease the efficiency of the

pump. This is because the gas occupies the pump cavity, thereby

further compression must be done to discharge the gas from the

cavity.

17

Limited temperature

capability

The pump is limited to a well temperature of about 100oC to 180oC

with the use of special elastomers. If the temperature goes beyond

the range, thermal swell will happens.

Limited production

rates

Due to the operating principle of the pump, the maximum production

rate is about 800 m3/d (approximately 5.040 bbls/d) in a large

diameter pumps while lower rate for a small diameter pump.

18

Chapter 5

Conclusion

For the past several decades, artificial lift has referred to the traditional method of downhole

pumping. The revolution of technology has broaden the uses of artificial lift. Today, artificial lift

is no longer limited referred as a methods applied in the wellbore only, but instead also used

throughout the production system to lift the production fluid to their final destination. There two

types of artificial lift that has been used quite some time which are gas lift and pumping system.

The progressing cavity pump (PCP) has been used as fluid transfer pump for many years.

It represents a widely used type of pump predominantly used for the transport of highly viscous

and non-lubricating fluid in petroleum industry. The use of progressing cavity pumps as a means

of artificial lift has numerous advantages over other artificial lift methods.

Through years of research and development in PCPs design, the production and lift

capabilities are expanding to cover a wide range of applications. With various elastomeric

materials available, a wide range of well fluids can be handled efficiently using the progressing

cavity pump. The ability to pump abrasive fluids lends itself well to many of the viscous sand

laden crudes found throughout the world. With present lift capabilities from 4000 feet and

capacities to 1000 BPD, the progressing cavity pump is ever expanding and becoming a viable

alternative for wells utilizing artificial lift. The most common PCPs design is one of a single helical

rotor rotating eccentrically inside a double threaded helical elastomeric stator of twice the pitch

length. The number of seal lines determines the pressure capabilities of the pump is one of the

determining factors of the slip experienced within the pump.

19

Reference

API Spec. 11B, Specification for Sucker Rods. 1990. Washington, DC: API.

API Spec. 5CT, Specification for Casing and Tubing. 1990. Washington, DC: API.

Cholet, H. (1997). Progressing Cavity Pumps retrieved from http://books.google.com /books?id

=e2v2YYqe4gwC&printsec=frontcover&dq=progressive+cavity+pump&hl=en&sa=X&ei=3n2

DUpGWHOeCyAGenIGwCw&ved=0CEoQ6AEwAA#v=onepage&q=progressive%20cavity%2

0pump&f=false

Colfax Corporation. (n.d.). Progressing Cavity Pumps. Monroe, Wisconsin, USA.

Gamboa, J. Gonzalez, P. Iglesias, J. & Olivet, A. (2003). Understanding the Performance of

Progressive Cavity Pump With A Metallic Stator. Symposium conducted at the Proceeding Of The

20th Pump User Symposium.

General Guidelines for Failure Analysis of Downhole Progressing Cavity Pumps. Retrieved on

November 5, 2013 from: www.oilproduction.net/cms/files/KenSaveth_Failure_analysis.pdf

Lange, J. and Strawn, J. 2006. Prime Movers. In Petroleum Engineering Handbook, Ch. 8.

Richardson, Texas: SPE.

Nelik, D., & Champlin, S. (2008, July). Focus on Fundementals (Part Four): Progressive Cavity

Pumps. Retrieved from Pumps&Systems: http://www.pump-zone.com/topics/pumps/progressing-

cavity/focus-fundamentals-part-four-progressive-cavity-pumps

PEH: Progressing Cavity Pumping System. Retrieved on November 5, 2013 from:

http://petrowiki.org/PEH%3AProgressing_Cavity_Pumping_Systems

Progressing Cavity Pump from KNOLL. Retrieved on November 5, 2013 from: http://blog.mx-

pumps.com/

Progressing Cavity Pump (PCP) System. Retrieved on November 5, 2013 from:

http://petrowiki.org/Progressing_cavity_pump_%28PCP%29_systems?rel=1

20

Stuart L. S. (May, 2006). Artificial Lift: Development Status of a Metal Progressing Cavity Pump

for Heavy-Oil and Hot-Production Wells.

Vetter, G., & Wirth, W. (n.d.). Understand Progressing Cavity Pumps Characteristics and Avoid

Abrasive Wear. Erlangen.

Weatherford (March, 2012). Weatherford: Introduction to Artificial lift System.

Wild, A. G. (n.d.). Progressing Cavity Pumps Proper Selection and Application. Robbins & Myers

Inc. Springfield. Ohio.

When To Use Progressive Cavity Pumps. Liberty Process. Retrieved on November 5, 2013 from:

http://www.libertyprocess.com/when_to_use_progressive_cavity_pumps.html

Woolsey, K. A (2010). Improving Progressing Cavity Pump Performance through Automation and

Surveillance. KUDU Industries Inc. Society of Petroleum Engineers

21

Appendices

Figure 4: Abrasive wear of the rotor

Figure 5: Elastomer swell

Figure 6: Torsional or fatigue failure

22

Gas Lift Foam Lift Plunger Rod Lift PCP ESP Hyd Jet Hyd

Piston

Max Depth 18,000 ft 22,000 ft 19,000 ft 16,000 ft 8,600 ft 15,000 ft 20,000 ft 17,000 ft

Max Volume 75,000 bpd 500 bpd 200 bpd 6,000 bpd 5,000 bpd 60,000 bpd 35,000 bpd 8,000 bpd

Max Temp 450°F 400°F 550°F 550°F 250°F 482°F 550°F 550°F

Corrosion

Handling

Good to

Excellent Excellent Excellent

Good to

Excellent Fair Good Excellent Good

Gas

Handling Excellent Excellent Excellent Fair to good Good Fair Good Fair

Solids

Handling Good Good Fair Fair to good Excellent

Sand

<40ppm Good Fair

Fluid

Gravity

(°API)

>15° >8° >15° >8° 8°<API<40° Viscosity

<400cp ≥6° >8°

Servicing Wireline or

workover rig

Capillary

Unit

Wellhead

Catcher or

Wireline

Workever or

pulling rig Wireline or workover rig Hydraulic or wireline

Prime Mover Compressor Well natural energy Gas or electric Electric Gas or Electric

Offshore Excellent Good N/A Limited Limited Excellent Excellent Good

System

Efficiency 10% -30% N/A N/A 45% – 60% 50% – 75% 35% – 60% 10% – 30%

45% –

55%

Source: Weatherford - Introduction to Artificial lift System