Selection of Artificial Lift Types

SELECTION OF ARTIFICIAL LIFT SELECTION OF ARTIFICIAL LIFT TYPESTYPES

AP Aung Kyaw

PAB2094

WELL COMPLETION AND

PRODUCTION

Well Completion and Production, PAB 2094

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1. Inflow and Outflow Performance

2. Review on artificial lift technique

3. Selection of artificial lift criteria

4. Rod pumps, electric submersible pumps, hydraulic

pumps, progressive cavity pumps, gas lift

5. Well performance analysis

LECTURE CONTENTSLECTURE CONTENTS


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Inflow and Outflow

Performance• INFLOW PREFORMANCE RELATIONSHIPS:

• Straight Line (PI):

• PI = Q / (PR – Pwf)Pwf = PR – Q / PI

• Vogel Relationship:

• Qo/Qomax = 1 – 0.2 (Pwf/PR) – 0.8 (Pwf/PR)2


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Inflow and Outflow

Performance Straight line vs. Vogel – Graphically


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Inflow and Outflow

Performance INFLOW AND OUTFLOW PERFORMANCE

SURFACE PRESSUREAt Wellhead

PRODUCED FLOWRATE

WELL OUTFLOWRELATIONSHIP

• If Pwf > Po, the well will flow naturally• (~10% of wells by number)

• If Pwf ≤ Po, the well will require Artificial Lift • (~90%)

Pwf

BOTTOM HOLEPRESSURE

Po

Reservoir Pressure- Pr WELL INFLOW (IPR)

Available PAvailable Pwfwf as function of the flow rate as function of the flow rate

Pwf


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Inflow and Outflow

Performance OUTFLOW PREFORMANCE

RELATIONSHIP:

Po = Ph + Pfr + Pwh

Where, Ph = Hydrostatic pressure

Pfr = Pressure drop due to friction losses

Pwh = Wellhead Pressure


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Introduction

Artificial lift - Any method used to raise oil to the surface

through a well after reservoir pressure has declined to the

point at which the well no longer produces by means of

natural energy.

It may prove necessary from the beginning of production for oil

wells when the reservoir does not have enough energy to

lift the fluid to the surface process facilities or when the

productivity index is inadequate.

The most common of artificial lift are: rod pumps, electrical

submersible pumps, hydraulic pumps, progressive cavity

pumps, Gas Lift.


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Gas Lift

ESP’s

PC Pumps

Hydraulic Pumps

Rod pump

ARTIFICIAL LIFT METHODS


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Review on artificial lift Technique

The most popular forms of artificial lift are illustrated in the figure below.

Fig.2 The most popular types of artificial lift


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Review on artificial lift technique

Rod Pump – A down-hole plunger is moved up and down by a rod

connected to an engine at the surface. The plunger movement

displaces produced fluid into the tubing via a pump consisting of

suitably arranged traveling and standing valves mounted within a pump

barrel.

Electric Submersible Pump (ESP) – employs a down-hole

centrifugal pump driven by a three phase, electric motor supplied

with electric power via a cable run from the surface penetrates the

wellhead and is strapped to the outside of the tubing.


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Review on artificial lift technique

Hydraulic Pump uses a high pressure power fluid to:

Drive a down-hole turbine or positive displacement pump

(or)

Flow through a venturi or jet, creating a low pressure area

which produces an increased drawdown and inflow from the

reservoir.

• Progressing Cavity Pump (PCP) – employs a helical, metal

rotor rotating inside an elastomeric, double helical stator.

The rotating action is supplied by down-hole electric motor or by

rotating rods.


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Selection of artificial Lift

Factors influencing the preferred form of artificial lift –

Well and Reservoir Characteristics

Field Location

Operational Problems

Economics

Implementation on Artificial Lift Selection Techniques

Long Term Reservoir Performance and Facility Constraints


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Rod Pump Pumps

The first type of artificial lift introduced to oil field; most widely used for the following reasons

Low cost

Mechanical simplicity

Easy installation and operation

Rod pumps can lift

o moderate volumes (1000 bfpd) from shallow depths (7,000 ft)

o Small volumes (200 bfpd) from greater depths (14,000 ft)


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Rod Pump Pumps

The surface equipment for a rod pump is illustrated in the following figure.

Prime mover – electric motor or gas engine

Gear Reducer – reduces the speed from low torque high rpm to high torque low rpm

Polished rod and sucker rods – connection between pumping unit and down-hole pump.

Polished rod moves up and down through a stuffing box which seals against the polished rod and prevents surface leaks.

Pumping Unit


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Rod Pump Pumps

The surface equipment for a rod pump

Fig.3


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Rod Pump

• Sucker Rods: 25 ft long, circular steel rods, outer diameter between

0.5 in and 1.125 in, threaded male connection or pin is machined at

each end, joined together by use of a double box coupling.

• Smaller diameter is to be installed at the lower part, larger diameter

at the upper part.

Sucker rods are joined together by a coupling


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Rod Pump Pumps

Plunger Pump

• located near perforations at the bottom of the sucker rods string

• consists of a hollow plunger with circular sealing rings mounted on the outside circumference

• moves inside a pump barrel which is either inserted into the tubing or is part of the tubing

Standing Valve – mounted at the bottom of pump barrel

Traveling Valve – installed at the top of plunger

Standing and Traveling valves contain a ball and seat assembly which closes the passage in the plunger and the pump inlet.


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Rod Pump d

Rod pump operation


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Electrical Submersible Pump(ESP)

-Electric submersible pumps are used as

an artificial lift method to produce from

150 to 60,000 bfpd.

-Effective and economical means of

lifting large volumes from great depths

-Performs at highest efficiency when

pumping liquid only

-Operating life expected 1 to 3 years

-Motor and pump rotates at 2,900 rpm

for 50 Hz power


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Electrical Submersible Pump

pumpsComponents included – High voltage electricity supply: power to drive motor

Vent box: eliminates gas travel up the cable to the switch

board

Down-hole cable: supplies power to the motor

Pump: -consists of multi-staged centrifugal pumps

-each stage consists rotating impeller and diffuser

-pumps the well fluid up to the surface

A rotary gas separator: separates free gas from well fluid

Protector or Seal: -connects pump housing to the motor

-prevents entry of well fluid into motor

Electric motor: driving force which turns the pump


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Electrical Submersible Pump

pumps


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Elect Electrical Submersible Pump

submersible pumps

ESP completion designs with gas

anchors to aid gas separation in the

casing

Vertical arrangement of gas anchors:

-makes separation of gas from liquid

-makes liquid entering into the bottom of pump


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A Advantages

submersible pumps


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Disadvantages


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Hydraulic pump

Hydraulic pump: use a high pressure power

fluid pumped from the surface

as the source of energy.

Subsurface pump: installed below working

fluid level

Power fluid: - directed to engine, and cause the

engine to reciprocate

- water, as well as oil can be used

Production fluid: directed towards the surface

by power fluid

-commingled with power fluid

or

-separate


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Hydraulic pump

Types of hydraulic pumps installation

“Open” Power Fluid System “Closed” Power Fluid System

Two Types of Power Fluid Systems: 1)Open Power Fluid System (OPF): power fluid mixes with

produced fluid and returns to the surface; separation conducted at surface

2)Closed Power Fluid System (CPF): surface power fluid does not

mix with the produced fluid


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Hydraulic pump

Advantages

Suitable for crooked and deviated wellsCan work at great depths (up to 17,000 ft)Supply of power fluid rate is controllable

No moving parts

Can handle solidsPower source is remote from the wellhead Power fluid can carry corrosion or other inhibitors Pump unit can be easily retrievable by using power fluid in reverse flow


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Hydraulic pump

Disadvantage

A similar volume of power fluid and

produced fluid is required, that is

increasing the size of the production

separators.


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Hydraulic pumps

Wells

Surface facilities for a Open Power Fluid SystemWELLS


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Hydraulic pump

Wells

Surface facilities for a Closed Power Fluid System


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Progressive Cavity Pump(PCP)

1. Used to produce viscous crude oils.

2. Electric motor and gear box mounted on

the surface.

3. Prime mover turns the strings of sucker

rods connected to the Progressing Cavity

Pump.

4. Latest Technology: Tendency of the failure

of tubing and Rods can be reduced by

placing the electric motor down the hole

(known as Progressing Cavity Electric

Submersible Pump, “PCESP”)

A well completed with artificial lift using a progressing cavity pump


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PCP

Progressing Cavity Displacement Pumps

Progressing cavity pumps are based on rotary fluid displacement. This spiral system consists of a rotor turning inside a stationary stator.


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Advantages

. Simple Design: easy to replace rotor and stator

. High Volumetric Efficiency: in absence of gas

. High energy Efficiency: acts as positive displacement pump

. Emulsions not formed due to low pumping action

. Capable of pumping viscous crude oils

Progressive cavity pump


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Progressive cavity pump

Disadvantages

• Elastomers swell in some viscous crude oils

• Problems with rotating rods increase with well depth


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Gas Lift

Gas Lift uses additional high pressure gas to supplement formation gas.

Produced fluids are lifted by reducing fluid density in wellbore to lighten the hydrostatic column, or back pressure, load on formations.


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Gas Lift as an Artificial Lift Method

Gas lift injection decreases fluid average density, thus the hydrostatic load on formations is reduced so that available reservoir energy can cause inflow, and commercial hydrocarbon volumes can be boosted or displaced to the surface.

By injecting relatively high pressure gas from the surface to a predetermined depth in the wellbore, the average specific gravity of the fluid decreases which causes a drop in the well face pressure (Pwf) generating additional draw-down which turns on increased fluid production.


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GL Equipment overview: Typical System


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Gas Lift – Advantages & Disadvantages

• Low operational and maintenance

cost

• Simplified well completions

• Flexibility – in well rates

• Typical rates go up to 35000 bpd

• Can best handle sand / gas / dev

well

• Can handle solids

• Must have a source of gas

• Requires treatment if gas is corrosive

• Possible high installation cost

• Top sides modifications to existing

platforms

• Compressor installation &

maintenance

• Well testing complexity

Advantages Disadvantages


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• Takes full advantage of the gas energy

available in the reservoir• High volume lift method• Valves may be retrieved by slick line or

tubing• Handle abrasives and sand

• Must have a gas source• Freezing and hydrates are problematic• Difficulty depleting low productivity and

low pressure wells completely

GL - Summary


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AL Methods Applicability

Condition Rod Pumps Hydraulic PumpsPCP's GL ESP'sScale fair fair/poor fair fair poorSand fair poor good very good fairParaffin poor poor good poor goodCorrossion good poor fair fair fairHigh GOR poor fair fair very good fairDeviation poor very good fair/good very good goodRate poor fair fair very good goodDepth fair very good fair good fairFlexibility very good very good good good good (with VSD)

Temperature very good good poor good good

Applicability of AL Methods


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QUIZ (4)

Write down the operating principle of following artificial lift systems.

(1)(2)

Documents

Selection of Artificial Lift Types