houston, 4 th & 5 th february 2003

23
Spring 2003 Gas Lift Workshop Spring 2003 Gas Lift Workshop Unlocking the Value in Marginal Mature Fields: Unlocking the Value in Marginal Mature Fields: “Chasing the Barrels by Field-wide “Chasing the Barrels by Field-wide Gas Lift Gas Allocation Optimisation” Gas Lift Gas Allocation Optimisation” Houston, 4 th & 5 th February 2003 PCL

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Spring 2003 Gas Lift Workshop Unlocking the Value in Marginal Mature Fields: “Chasing the Barrels by Field-wide Gas Lift Gas Allocation Optimisation”. Houston, 4 th & 5 th February 2003. 10°W. 0°E. 10°E. 60°N. Aberdeen. 50°N. Scott / Telford. UKCS Blocks 15/21a & b outer Moray Firth. - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: Houston, 4 th  & 5 th  February 2003

Spring 2003 Gas Lift WorkshopSpring 2003 Gas Lift Workshop

Unlocking the Value in Marginal Mature Fields:Unlocking the Value in Marginal Mature Fields:“Chasing the Barrels by Field-wide “Chasing the Barrels by Field-wide

Gas Lift Gas Allocation Optimisation”Gas Lift Gas Allocation Optimisation”

Houston, 4th & 5th February 2003

PCLPCL

Page 2: Houston, 4 th  & 5 th  February 2003

20 April 2023 2

IVANHOE, ROB ROY, HAMISH FIELDS - LOCATION

10^0'W 0^0'E 10^0'E

60^0

'N50

^0'N

10°W 10°E0°E

60

°N5

0°N

Aberdeen

UKCS Blocks 15/21a & bouter Moray Firth

Scott / Telford

Page 3: Houston, 4 th  & 5 th  February 2003

20 April 2023 3

IVANHOE, ROB ROY, HAMISH FIELDS - DEVELOPMENT SCHEMATIC

Page 4: Houston, 4 th  & 5 th  February 2003

20 April 2023 4

IVANHOE, ROB ROY, HAMISH FIELDS - TOP RESERVOIR

0 2km

IvanhoeRob Roy

Hamish

Page 5: Houston, 4 th  & 5 th  February 2003

20 April 2023 5

IVANHOE, ROB ROY, HAMISH FIELDS - RESERVOIR CHARACTER

Supra Piper

Mid Shale

Main Piper

GR FDC/CNL K PHI DT

Basal shale

Page 6: Houston, 4 th  & 5 th  February 2003

20 April 2023 6

IVANHOE, ROB ROY, HAMISH FIELDS - PRODUCTION HISTORY

On stream 1989

Original reserves at start-up = 88 mmbls

Original field life 10 years

Projected field life extended several times

IV/RR/H PRODUCTION COMPARISON

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2002

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op

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original Actual

Projected end of field life 2006

Current reserves estimates 187 mmbbl

Aquifer support + Water injection + Gas lift

The fields have always “over performed”

Page 7: Houston, 4 th  & 5 th  February 2003

20 April 2023 7

IVANHOE, ROB ROY, HAMISH FIELDS - GAS LIFT SYSTEM

Gas lift type & description: Continuous gas lift (gas is injected at a constant rate into the tubing) There is a common gas lift line into each subsea manifold, it is fitted with pressure & temperature transmitters located upstream the gas lift subsea choke.

Gas lift Characteristics: A system of subsea wellhead transmitters, each subsea wellhead is fitted with a flow transmitter, pressure & temperature transmitters, they can be interrogated in real time. There is also at a gas lift choke at each individual wellhead.

Page 8: Houston, 4 th  & 5 th  February 2003

20 April 2023 8

IVANHOE, ROBROY, HAMISH FIELDS - GAS LIFT SYSTEM

Why should we care about gas lift optimisation?

Have a look at the production pie in IVRRH

IVRRH Production Pie

Natural flow Gas lift flow

Page 9: Houston, 4 th  & 5 th  February 2003

20 April 2023 9

Gas lift contribution to overall production has increased from 40% at the beginning of last year to the current 55% .

This percentage was reduced to approximately 40% after the well intervention in IJ57 (re-perforations) and the new well drilled last year. It has increased again and will continue as the fields mature and water cut levels increase.

IVRRH Production: Natural flow vs Gas lift flow

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IVANHOE, ROBROY, HAMISH FIELDS - GAS LIFT SYSTEM

Page 10: Houston, 4 th  & 5 th  February 2003

20 April 2023 10

IVANHOE, ROBROY, HAMISH FIELDS - GAS LIFT SYSTEM

One key aspect of a gas lift system is the interaction between wells in the gathering network as back-pressure from additional gas in the flowline adversely affects production from all the other connected wells.

The ‘optimal’ gas lift injection rate generally determined from a single-well analysis method has limited validity in analysing a production network of gas lifted wells.

The oil production loss due to back-pressure effect in IVRRH gas lift system was estimated to be approximately 1,000 bbls/d.

Therefore the need for a system approach to gas lift allocation optimisation based on a model that would optimise field-wide gas lift allocation.

Page 11: Houston, 4 th  & 5 th  February 2003

20 April 2023 11

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

GAP is a network analysis program that models the production gathering network from sandface through to the separator(s).

The production system is simplified by combining the responses at each node until the entire system is represented by a single optimised performance curve

Page 12: Houston, 4 th  & 5 th  February 2003

20 April 2023 12

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

Define system components: tank or reservoir, wells, joints, pipelines, separators...

Draw the system schematic: graphically link components, e.g. pipeline connections

Page 13: Houston, 4 th  & 5 th  February 2003

20 April 2023 13

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

Page 14: Houston, 4 th  & 5 th  February 2003

20 April 2023 14

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

Generate & validate well performance: An automatic procedure allows GAP to control Prosper for generation of lift curve solutions.

Allocate lift gas: It is the calculation procedure used to assign gas to gas lifted wells and calculate production rates and pressures throughout the system.

Production optimisation: It consists of finding the optimum volume of lift gas to inject to each well. GAP allocates gas increments until all gas is allocated or maximum production is achieved.

Page 15: Houston, 4 th  & 5 th  February 2003

20 April 2023 15

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

Gap uses three methods of optimisation:

Production: This option maximises the oil production rate, and GAP calculates the maximum rate that can be achieved for a specified volume of lift gas available.

Revenues: This option optimises the revenues generated by sales of oil & gas produced after taking into account the costs of processing water and injection gas.

Start-up scenario: This option optimises the amount of free gas produced, it will be used to rank wells in order of gas production in situations of limited lift gas supply.

Page 16: Houston, 4 th  & 5 th  February 2003

20 April 2023 16

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

Once the system is defined (all wells with valid IPR & VLP data and all pipelines calibrated), the model solves the network system for pressure and rates at various nodes by either:

Network Solver option: It finds pressure and flow distributions in the network given fixed separator pressures. The gas allocation is set manually to each well and the model performs network calculations

Network Optimiser option: It optimises the returns of oil produced, revenues or gas produced. Let the model calculate the optimum amount of gas injected to each well to maximise production

Page 17: Houston, 4 th  & 5 th  February 2003

20 April 2023 17

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

############################################

# RESULTS - SUMMARY REPORT FOR ALL WELLS #

############################################

System : IVRRH Production System Schematic

System type : Production

Optimisation Method : Production

Pipeline prediction : Pressure and temperature

Gas Available : 28.00 MMscf/day

Gas injected : 24.88 MMscf/day

Oil produced : 7924.46 STB/day

Gas produced : 3.47 MMscf/day

Water produced : 44432.25 STB/day

Liquid produced : 52356.72 STB/day

Name Oil

Produced

STB/day

--------------- -----------

57 3184.35

28 1367.95

31 703.44

24 666.84

40 78.20

27 1189.83

32 0.47

25 733.40

+++++++++++++++++++

+ End of report +

+++++++++++++++++++

Page 18: Houston, 4 th  & 5 th  February 2003

20 April 2023 18

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

############################################

# RESULTS - SUMMARY REPORT FOR ALL WELLS #

############################################

System : IVRRH Production System Schematic

System type : Production

Optimisation Method : Production

Pipeline prediction : Pressure and temperature

Gas Available : 28.00 MMscf/day

Gas injected : 28.00 MMscf/day

Oil produced : 8481.35 STB/day

Gas produced : 3.57 MMscf/day

Water produced : 45987.56 STB/day

Liquid produced : 54468.90 STB/day

Name Oil

Produced

STB/day

--------------- -----------

57 3997.98

28 852.86

31 1014.03

24 565.47

40 47.33

27 1240.50

32 152.31

25 610.87

+++++++++++++++++++

+ End of report +

+++++++++++++++++++

Page 19: Houston, 4 th  & 5 th  February 2003

20 April 2023 19

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

############################################

# RESULTS - SUMMARY REPORT FOR ALL WELLS #

############################################

System : IVRRH Production System Schematic

System type : Production

Optimisation Method : Production

Pipeline prediction : Pressure and temperature

Gas Available : 28.00 MMscf/day

Gas injected : 28.00 MMscf/day

Oil produced : 8836.45 STB/day

Gas produced : 3.67 MMscf/day

Water produced : 44688.90 STB/day

Liquid produced : 53525.36 STB/day

Name Oil

Produced

STB/day

--------------- -----------

57 4393.70

28 883.16

31 1092.68

24 575.84

27 1286.52

25 604.55

+++++++++++++++++++

+ End of report +

+++++++++++++++++++

Page 20: Houston, 4 th  & 5 th  February 2003

20 April 2023 20

IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

#####################################

# RESULTS - SYSTEM SUMMARY REPORT #

#####################################

System : IVRRH Production System Schematic

System type : Production

Optimisation Method : Production

Pipeline prediction : Pressure and temperature

Gas Gas Oil Gas Water Oil Gas Revenue

available injected Produced Produced Produced Gravity Gravity Generated

MMscf/day MMscf/day STB/day MMscf/day STB/day API sp. gravMM US doll

--------- --------- --------- --------- --------- --------- --------- ---------

0.00 0.00 5592.77 2.56 21791.55 33.7111 0.84

10.00 10.00 8391.19 3.48 36723.60 33.3662 0.82

15.00 11.66 8282.83 3.49 36670.50 33.3107 0.82

20.00 20.00 8706.09 3.56 42932.99 33.5149 0.81

25.00 25.00 8888.47 3.66 44481.04 33.5079 0.81

30.00 30.00 8769.06 3.65 44939.06 33.4983 0.81

35.00 30.42 8710.91 3.67 44505.83 33.4987 0.81

+++++++++++++++++++

+ End of report +

+++++++++++++++++++

Page 21: Houston, 4 th  & 5 th  February 2003

20 April 2023 21

The incremental net oil production due to gas lift gas allocation optimisation is estimated at 6% of the total production, this is approximately equivalent to 400 bbls/d.

The modelling of gas lift gas allocation on a field-wide basis has allowed us to better understand and reduce the adverse back-pressure effects within the flowlines. This has accelerated cash flow and generated profit estimated at US $ 2.5 millions for year 2001.

306 days x 400 bbl/d x 0.85 (production uptime) = 104,000 bbls/year 104,000 x 24 $/bbl = US $ 2.5 millions

Unlocking Value: IVRRH Production

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IVANHOE, ROBROY, HAMISH FIELDS - GAP MODELLING

Page 22: Houston, 4 th  & 5 th  February 2003

20 April 2023 22

GAS LIFT PRODUCTION SYSTEM MODELLING - THE FUTURE

As This example shows, a field-wide gas lift allocation optimisation can contribute

to maximise the value of marginal and mature fields up to 10% gain in oil

production, accelerate cash flow and generate profit sooner.

Page 23: Houston, 4 th  & 5 th  February 2003

20 April 2023 23

GAS LIFT PRODUCTION SYSTEM MODELLING - THE FUTURE

The key to gas lift optimisation modelling is predicting the effects of

changes, the gas lift optimisation should always be a proactive and

continuing monitoring process

( it is to do with being effective.

Effectiveness as doing the right thing, e.g. have a reliable simulation model…)

Once the monitoring process is predictable, the gas lift gas allocation

model becomes a production optimisation tool ( it

is to do with being efficient. Efficiency

as being better in what we do: optimise production…)