The Use of Stability Maps The Use of Stability Maps in the Design - - PowerPoint PPT Presentation

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The Use of Stability Maps The Use of Stability Maps in the Design - - PowerPoint PPT Presentation

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The Use of Stability Maps The Use of Stability Maps in the Design and Operation of in the Design and Operation of Gas- -Lift Wells Lift Wells Gas 1 and I. Guerrero Y. V. Fairuzov 1 and I. Guerrero- -Sarabia Sarabia 2 2 , , Y. V. Fairuzov

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SLIDE 1

The Use of Stability Maps The Use of Stability Maps in the Design and Operation of in the Design and Operation of Gas Gas-

  • Lift Wells

Lift Wells

  • Y. V. Fairuzov
  • Y. V. Fairuzov1

1 and I. Guerrero

and I. Guerrero-

  • Sarabia

Sarabia2

2,

, National Autonomous University of Mexico National Autonomous University of Mexico

1fairuzov@servidor.unam.mx; 2iguerreros@iingen.unam.mx

2006 ASME/API/ISO Gas-Lift Workshop, February 15-16, 2006, Houston, Texas

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SLIDE 2

Outline Outline

  • Introduction
  • Stability Maps for Continuous Flow Gas-Lift Wells
  • Comparison of Different Gas-Lift Stability Criteria
  • Stability Map Applications

Effect of Orifice Size Effect of Tubing Diameter Effect of Injection Depth Effect of Inflow Performance Selection of Stabilization Method

  • Conclusions
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SLIDE 3

Heading in a Gas Heading in a Gas-

  • Lift Well

Lift Well

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SLIDE 4

Problems caused by flow Problems caused by flow

  • scillations in gas lifted wells
  • scillations in gas lifted wells

Operational problems

– difficulties with operation of low pressure separator – compressor shutdown

Low efficiency Problems with production control Monitoring (more difficult to measure

production rates)

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SLIDE 5

Gas Gas-

  • Lift Performance Curves

Lift Performance Curves

1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 Gas Injection (MMscf/d) Production (Mb/d)

10 15 20 Wellhead Pressure (kg/cm2)

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SLIDE 6

Factors Affecting Gas Factors Affecting Gas-

  • Lift Stability

Lift Stability

1.

Fluid properties (crude oil and injected gas)

2.

Inflow performance

3.

Reservoir pressure

4.

Tubing diameter

5.

Casing diameter

6.

Orifice valve size

7.

Injection depth

8.

Injection gas rate

9.

Wellhead pressure

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SLIDE 7

Existing Techniques and Existing Techniques and Recommendations Recommendations

1.

Sizing of the injection port (pressure differential of 100-200 psi) ⇒ increased gas compression costs/pipe wall thickness

2.

Increasing the injection gas rate ⇒ inefficient operation

3.

Choking at the surface (increasing the wellhead pressure) ⇒ uneconomical production

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SLIDE 8

Existing Methods to Analyze Existing Methods to Analyze Flow Stability in Gas Flow Stability in Gas-

  • Lift Wells

Lift Wells

Sensitivity analysis based on gas-lift

stability criteria (linear stability analysis)

Transient models (non-linear stability

analysis)

Both methods - time-consuming and

tedious procedures

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SLIDE 9

Gas Gas-

  • Lift Application in

Lift Application in Offshore Oil Production Offshore Oil Production

Large–scale oil production High percentage of H2S Gas processing- onshore Long pipelines to transport lift gas Pressure variations in the gas allocation

network

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SLIDE 10

Boiling Water Reactor (BWR) Boiling Water Reactor (BWR)

Assembly Assembly Schematic Schematic

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SLIDE 11

Typical BWR Stability Map Typical BWR Stability Map

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SLIDE 12

Continuous Flow Gas Continuous Flow Gas-

  • Lift Well

Lift Well

Lift gas Oil

1 Reservoir 2 Packer 3 Tubing 4 Operating valve 5 Casing 6 Gas allocation network 7 Surface injection choke 8 Wellhead 9 Choke 10 Flowline

1 10 3 4 5 8 9 7 6 2 Lift gas Oil

1 Reservoir 2 Packer 3 Tubing 4 Operating valve 5 Casing 6 Gas allocation network 7 Surface injection choke 8 Wellhead 9 Choke 10 Flowline

1 10 3 4 5 8 9 7 6 2 Lift gas Oil

1 Reservoir 2 Packer 3 Tubing 4 Operating valve 5 Casing 6 Gas allocation network 7 Surface injection choke 8 Wellhead 9 Choke 10 Flowline

1 10 3 4 5 8 9 7 6 2 Lift gas Oil

1 Reservoir 2 Packer 3 Tubing 4 Operating valve 5 Casing 6 Gas allocation network 7 Surface injection choke 8 Wellhead 9 Choke 10 Flowline

1 10 3 4 5 8 9 7 6 2 Lift gas Oil

1 Reservoir 2 Packer 3 Tubing 4 Operating valve 5 Casing 6 Gas allocation network 7 Surface injection choke 8 Wellhead 9 Choke 10 Flowline

1 10 3 4 5 8 9 7 6 2 1 10 3 4 5 8 9 7 6 2 10 3 4 5 8 9 7 6 2

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SLIDE 13

GME Computer Program GME Computer Program (Stability Map Generator) (Stability Map Generator)

Specify Specify system system

  • perating
  • perating

conditions conditions Predict Predict steady steady-

  • state

state flow flow parameters parameters Select Select gas gas-

  • lift

lift stability stability criteria criteria Gas Gas-

  • lift well

lift well stability map stability map

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SLIDE 14

Gas Gas-

  • Lift Stability Map

Lift Stability Map

5 10 15 20 25 30 35 1 2 3 4 5 6 7 Gas Injection (MMscf/d) Wellhead Pressure (kg/cm

2)

Stability Boundary

Upper limit Lower limit Fairuzov and Guerrero, 2004

Stable Operability Boundaries Unstable Non - Operational

GME Ver. 3.0

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SLIDE 15

(psig) 1550.23 Bubble pressure (SBT/STB) 0.0 Water oil ratio (scf/STB) 291.46 Solution GOR (sp. gravity) 0.675 Gas lift gravity (sp. gravity) 0.922 Gas gravity (API) 21.4 Oil gravity (psig) 1363.5 Flowing bottomhole pressure (STB/day) 7632.0 Liquid rate (percent) 0.0 Water cut (° F) 216.9 Reservoir temperature (psig) 1543.31 Reservoir pressure

Well Well Data

Data

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SLIDE 16

Stability Map for Gas Stability Map for Gas-

  • Lift Well with Square

Lift Well with Square-

  • Edged Orifice Valve

Edged Orifice Valve

5 10 15 20 25 30 35 40 45 1 2 3 4 5 6 7 8 9 10 Gas Injection Rate (MMscf/d) Wellhead Pressure (kg/cm2) Operability Boundaries

Lower limit Upper limit

Stability Boundary Optimal Rate Non - Operational Stable Unstable

GME Ver. 3.0

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SLIDE 17

Field Data Field Data

1280 1300 1320 1340 1360 1380 1400 1420 1440 1460 1480 19-15:50 19-20:38 20-01:26 20-06:14 20-11:02 20-15:50 Day - Hour [dd-hh:mm]

BOTTOMHOLE PRESSURE [psia]

150 200 250 300 350 400

WELLHEAD PRESSURE [psia] Bottomhole pressure Wellhead pressure

5.5 MMscfd (Choke size: 2.5") 4.0 MMscfd 3.0 MMscfd 4.5 MMscfd 5.0 MMscfd 5.5 MMscfd

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SLIDE 18

Comparison of Gas Comparison of Gas-

  • Lift

Lift Stability Criteria Stability Criteria

5 10 15 20 25 30 35 1 2 3 4 5 6 7 Gas Injection (MMscf/d) Wellhead Pressure (kg/cm

2)

Stable Unstable

Field Data Stability Boundaries

Asheim, 1988 Fairuzov and Guerrero, 2004 Alhanati et al., 1993 Lower limit

Operability Boundary Non - Operational Stable Unstable

GME Ver. 3.0

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SLIDE 19

Effect of Orifice Size Effect of Orifice Size

5 10 15 20 25 30 35 1 2 3 4 5 6 7 Gas Injection (MMscf/d) Wellhead Pressure (kg/cm

2)

Stability Boundaries

0.75 in. 1.00 in. 0.50 in.

Lower limit

All cases 0.50 in.

Non - Operational Stable Operability Boundaries Orifice size Unstable Upper limit

GME Ver. 3.0

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SLIDE 20

Effect of Tubing Diameter Effect of Tubing Diameter (d (dc

c=11 7/8 in.)

=11 7/8 in.)

5 10 15 20 25 30 35 1 2 3 4 5 6 7 Gas Injection (MMscf/d) Wellhead Pressure (kg/cm

2)

Stability Boundaries

7 5/8 in. 5 1/2 in. 9 5/8 in.

Lower limit

7 5/8 in. and 9 5/8 in.

Tubing diameter Unstable Stable Non - Operational Operability Boundary

GME Ver. 3.0

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SLIDE 21

Effect of Injection Depth Effect of Injection Depth

5 10 15 20 25 30 35 1 2 3 4 5 6 7 Gas Injection (MMscf/d) Wellhead Pressure (kg/cm

2)

Stability Boundaries

6174 ft. 6830 ft. 5518 ft.

Lower limit

All cases

Unstable Stable Operability Boundary Non - Operational Injection depth

GME Ver. 3.0

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SLIDE 22

Effect of Inflow Performance Effect of Inflow Performance ( (q qo

  • =7632 bpd)

=7632 bpd)

5 10 15 20 25 30 35 1 2 3 4 5 6 7 Gas Injection (MMscf/d) Wellhead Pressure (kg/cm

2)

Stability Boundaries

8.4 kg/cm 2 12.7 kg/cm 2 4.2 kg/cm 2

Lower limit

All cases

Unstable Stable Operability Boundary Non - Operational Drawdown

GME Ver. 3.0

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SLIDE 23

Selection of Stabilization Method Selection of Stabilization Method

5 10 15 20 25 30 35 1 2 3 4 5 6 7 Gas Injection (MMscf/d) Wellhead Pressure (kg/cm

2)

Design operating condition

Unstable Stability Boundaries Well stimulation Reduced choke size

Lower limit

Only for reduced choke size

Upper limit

All cases Design conditions Decreased injection depth

Stable Stable Unstable Unstable Non Non -

  • Operational

Operational

GME Ver. 3.0

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SLIDE 24

Oil Production Rate Oil Production Rate

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 1 2 3 4 5 6 7 Qgi [MMpcd] Qo [bpd] Pwh [kg/cm2] 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Stable Unstable 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 1 2 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 1 2 3 4 5 6 7 Qgi [MMpcd] Qo [bpd] Pwh [kg/cm2] 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Stable Unstable

GME Ver. 3.0

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SLIDE 25

Selection of Stabilization Method Selection of Stabilization Method

5 10 15 20 25 30 35 1 2 3 4 5 6 7 Gas Injection (MMscf/d) Wellhead Pressure (kg/cm

2)

Design operating condition

Unstable Stability Boundaries Well stimulation Reduced choke size

Lower limit

Only for reduced choke size

Upper limit

All cases Design conditions Decreased injection depth

Stable Stable Unstable Unstable Non Non -

  • Operational

Operational

GME Ver. 3.0

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SLIDE 26

Conclusions Conclusions

  • Stability maps

Stability maps can be used to compare different gas-lift stability criteria.

Existing stability criteria may significantly

underestimate the instability threshold for gas-lift wells producing from saturated reservoirs.

New criteria predict more accurately the

instability boundary

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SLIDE 27

Conclusions (cont.) Conclusions (cont.)

  • Gas-lift design:

the effect of gas-lift design parameters and

  • perating conditions on the system stability
  • Operation:

what actions should be taken to bring the system into a stable operating state with a minimum increase in operational expenditures

  • Gas-lift optimization
  • Training and education