well performance and artifical lift rev 3

INTRODUCTION TO WELL PERFORMANCE

& ARTIFICIAL LIFT

November 2001

by Russ Gilbert & Justin Gilmour

= $$$$$

the well

What is a well?Why is it important ?

WHY BOTHER WITH WELL PERFORMANCE ?

• Basic Well Configuration

• Reservoir Inflow Performance

• Tubing Outflow Performance

• Improving Well Performance

INTRODUCTION TO WELL PERFORMANCE

CONCEPTS COVERED

BASIC WELL CONFIGURATIONXMAS TREE

Hydrocarbon Flow

CASING

TUBING OUFLOW

PERFORATIONS

RESERVOIR

RESERVOIR INFLOW

Gas Export

Oil Export= $$$$

Separator

RESERVOIR INFLOW

oil rate

PRESSURE DROP

Reservoir pressure(Pres)

Inflow Performance Principle:

Pre

ssu

re

As pressure drop increases rate increases!

Can we model this principle?

pres

sure

BHP

Pres

ΔP ΔP

Wellbore Damage (Skin)

BHPBottomhole pressure

(BHP)

Higher Pressure(Driving Force)

RESERVOIR INFLOWMathematical Model

Flow Rate (Q) varies with: - Inflow Pressure Drop? (ΔP)- Thickness of the Reservoir? (h)- Permeability of the Reservoir Sand? (k)- Phase of the Moon? (x)- Skin Damage around the Well? (S)- Reservoir Pressure? (Pres)- Fluid Viscosity? (µ)- Hours of Sunshine? (y)- Wellbore Radius (rw)

pres

sure

BHP

Pres

ΔP

BHP

ΔP

Q = f ?

RESERVOIR INFLOWMathematical Model

Various inflow equations are used to model reservoir inflow in software such as Prosper

Flow Rate (Q) varies with: - Inflow Pressure Drop? (ΔP)- Thickness of the Reservoir? (h)- Permeability of the Reservoir Sand? (k)- Phase of the Moon? (x)- Skin Damage around the Well? (S)- Reservoir Pressure? (Pres)- Fluid Viscosity? (µ)- Hours of Sunshine? (y)- Wellbore Radius (rw)

pres

sure

BHP

Pres

ΔP

BHP

ΔP

Q = fK h ΔP rw

µ S

TUBING OUTFLOW

Tubing Performance Principle:

pres

sure

oil rate

PRESSURE LOSS

Higher Pressure(Driving Force)

Lower Pressure

BHP

WHP

As rate increases pressure loss increases!

Can we model this principle?

Bottomhole pressure(BHP)

Well Head pressure(WHP)

TUBING OUTFLOW

BHP

WHP

Mathematical Model

Flow Rate (Q) varies with: - Fluid Weight/Type? (ρ)- Friction Losses - Fluid Viscosity? (μ)- Friction Losses - Tubing Length? (L)- Phase of the Moon? (x)- Friction Losses - Tubing diameter ? (d)- Friction Losses - Tubing roughness ? (f)- Hours of Sunshine? (y)- Well Head Pressure? (WHP)

Q = f ?

Note: The acceleration term (velocity increasing due to gas expansion) has been assumed to be negligible for this presentation.

TUBING OUTFLOW

BHP

WHP

Mathematical Model

Flow Rate (Q) varies with: - Fluid Weight/Type? (ρ)- Friction Losses - Fluid Viscosity? (μ)- Friction Losses - Tubing Length? (L)- Phase of the Moon? (x)- Friction Losses - Tubing diameter ? (d)- Friction Losses - Tubing roughness ? (f)- Hours of Sunshine? (y)- Well Head Pressure? (WHP)

Various correlations are used to model tubing outflow in software such as Prosper

Q = f1

Fluid Weight . Friction Losses . Wellhead Pressure

Note: The acceleration term (velocity increasing due to gas expansion) has been assumed to be negligible for this presentation.

TUBING OUTFLOWFluid Weight/Type

0 5000 10000 15000 200000

1000

2000

3000

4000

5000

6000

VLP (TUBING) CURVES ( 20 Nov 01 16:11)

Liquid Rate (STB/day)

Pre

ssur

e (

psig

)

FluidOilFlow TubingTypeProducer

Lift NoneCompCased HoleCorrlnHagedorn Brown

Bottom Measured Depth 10000.0(feet)Bottom True Vertical Depth 10000.0(feet)

Variables1:Water Cut (percent)2:First Node Pressure (psig)3:Tubing/Pipe Diameter (inches)

1 2 30=0 0=50.0 0=1.99

1=50.000 1=200.0 1=2.752=90.000 2=400.0 2=3.83

3=4.89

002

102

202

Mixture

All Wtr

50/50

All Oil

Tubing Length=10,000ft; Tubing Diameter=4 1/2”OD;WHP=50psig

TUBING OUTFLOWFriction Losses

Tubing Length=10,000ft; All Oil; WHP=50psig

0 5000 10000 15000 200000

1000

2000

3000

4000

5000

6000



Pre

ssur

e (

psig

)





1 2 30=0 0=50.0 0=1.99

1=50.000 1=200.0 1=2.752=90.000 2=400.0 2=3.83

3=4.89

000

001

002

003

Tubing OD

2 3/8”

4 1/2”

5 1/2”

3 1/2”

TUBING OUTFLOWWell Head Pressure

0 5000 10000 15000 200000

1000

2000

3000

4000

5000

6000



Pre

ssur

e (

psig

)





1 2 30=0 0=50.0 0=1.99

1=50.000 1=200.0 1=2.752=90.000 2=400.0 2=3.83

3=4.89

002

012

022

Tubing Length=10,000ft; All Oil; Tubing Diameter=4 1/2”

Well Head Pressure

400 psig

200 psig

50 psig

THE OIL RATE

Determined for specific fluid, specific tubing & specific reservoir by intersection of the reservoir inflow & tubing outflow curves

oil rate

pres

sure

from tubing outflow

surface pressure - WHP

from reservoir inflow

reservoir pressure - Pres

THE OIL RATE

0 5000 10000 15000 200000

1000

2000

3000

4000

5000

6000

Inflow v Outflow Curves ( 20 Nov 01 17:04)


Pre

ssur

e (

psig

)



First Node Pressure 50.0(psig)Bottom Measured Depth 10000.0(feet)

Bottom True Vertical Depth 10000.0(feet)

IPR PI EntryRes Temp200.0 (degrees F)Res Pres 3000.0 (psig)

Variables1:Reservoir Pressure (psig)

1 2 30=3000.01=4000.02=5000.0

2

2

IPR Curve

VLP Curve

Tubing Length=10,000ft; All Oil; Tubing Diameter=4 1/2”; WHP=50psig, Pres=5000psig, k.h=10000mdft, rw=8.5”, Wellbore Skin=5

Reservoir Pressure

5000 psig

Initial Conditions

6500 bopd

THE OIL RATEPressure Depletion

0 5000 10000 15000 200000

1000

2000

3000

4000

5000

6000



Pre

ssur

e (

psig

)







1 2 30=3000.01=4000.02=5000.0

0

0

1

1

2

2

IPR Curve

VLP CurveReservoir Pressure

5000 psig

4000 psig

3000 psig

6500 bopd2500 bopd

Tubing Length=10,000ft; All Oil; Tubing Diameter=4 1/2”; WHP=50psig, Pres=depleting, k.h=10000mdft, rw=8.5”, Wellbore Skin=5

THE OIL RATEPressure Depletion & %Water Increase

Tubing Length=10,000ft; %wtr increasing; Tubing Diameter=4 1/2”; WHP=50psig, Pres=depleting, k.h=10000mdft, rw=8.5”, Wellbore Skin=5

0 5000 10000 15000 200000

1000

2000

3000

4000

5000

6000



Pre

ssur

e (

psig

)







1 2 30=3000.01=4000.02=5000.0

0

0

1

1

2

2

IPR Curve

VLP CurveReservoir Pressure

5000 psig

4000 psig

3000 psig

%Water

100%

50% (Now)

0%Now 4500 psig

3000 bfpd

THE OIL RATEPressure Depletion & %Water Increase

What can we do to stop oil rate falling ?

Was 6,500 bopd, now 1500 bopd

IMPROVING WELL PERFORMANCE

pres

sure

Oil rate can be increased by:• Shifting reservoir inflow up • Shifting tubing outflow curve down

oil rate

Tubing outflow

surface pressure - WHP

Reservoir inflow)

reservoir pressure - Pres

How Do You Do That Then ?

IMPROVING WELL PERFORMANCEShifting Reservoir Inflow Curve Up - How To

Q = fK h ΔP rw

µ S

Increase

Decrease

Increase: Kh, ΔP rw Decrease: µ S

IncreaseReservoirPressure

Re-Perf.,Acidise,Fracture,Dissolve

Heat-UpFracture,Horizontal

Well

DrillBiggerHole

IMPROVING WELL PERFORMANCEShifting Tubing Outflow Curve Down - How To

Q = f1


Reduce: Fluid Weight, Friction Losses, Wellhead Pressure

Isolate WtrProdn orAdd gas

via gas lift(aka artificial lift)

BiggerTubing

LowerSeparatorPressure

No Action:Rate = 3000bfpd

Well Will Die Soon

0 5000 10000 15000 200000

1000

2000

3000

4000

5000

6000



Pre

ssur

e (

psig

)







1 2 30=3000.01=4000.02=5000.0

0

0

1

1

2

2

IPR Curve

VLP CurveP res

5000 psig

4000 psig

3000 psig

%Water

100%

50%

0%

Shifting Reservoir Inflow Curve UpIMPROVING WELL PERFORMANCE





Well

DrillBiggerHole

Actions: (1) N/A N/A Later Re-perf N/A

4000 bfpd

0 5000 10000 15000 200000

1000

2000

3000

4000

5000

6000



Pre

ssur

e (

psig

)







1 2 30=3000.01=4000.02=5000.0

0

0

1

1

2

2

IPR Curve

VLP CurveP res

5000 psig

4000 psig

3000 psig

%Water

100%

50%

0%

50% +G/L

Shifting Tubing Outflow Curve Down

No Further Action:Rate = 4000bfpd

Well Will Still Die Soon


Reduce: Fluid Weight, Friction Losses, Wellhead Pressure

Isolate WtrProdn,

Add gasvia gas lift

BiggerTubing

LowerSeparatorPressure

Actions: (2) Add G/L N/A N/A

7500 bfpd

Shifting Reservoir Inflow Curve Up

No Further Action:Rate = 7500bfpd

Well Will Still Die, But Later

0 5000 10000 15000 200000

1000

2000

3000

4000

5000

6000



Pre

ssur

e (

psig

)







1 2 30=3000.01=4000.02=5000.0

0

0

1

1

2

2

IPR Curve

VLP CurveP res

5000 psig

4000 psig

3000 psig

%Water

100%

50%

0%

50% +G/L






Well

DrillBiggerHole

Actions: (3) N/A N/A Wtr Injector N/A N/A

10000 bfpd


Actions to improve well performancehave almost returned oil rate to initial condition

SUMMARY• Basic Well Configuration

• Reservoir Inflow Performance

• Tubing Outflow Performance

• Improving Well Performance

Q = f K h ΔP rw

µ S

Q =f1


Shifting Reservoir Inflow Curve Up

Shifting Tubing Outflow Curve Down

well performance and artifical lift rev 3

Documents

velocity increasing

drill bigger

lower separator

tubing diameter4

isolate wtr

inflow pressure

increase reservoir

bigger tubing