ASME/API Gas-Lift Workshop12 – 13th November 2001

Aberdeen, Scotland

Predicting Future Gas Lift Performance in a Mature

Water Flooded Field

Tony Liao & Simon Bishop, BP

Miller Field

Location of Miller Field

Miller Field Background

>Discovered in late 1982>Oil was found 4,000 meters beneath the seabed

in a water depth of 100 meters>The field lies 270km NE of Aberdeen>Estimated 240 million barrels of recoverable oil

and 480 billion cubic feet of associated gas

Miller Field Background

>Oil production commenced in May 1992 >Gas production following about two months

later>Brae field has been on production since 1983>Reservoir pressure in Miller has declined while

Brae has been produced

Objective

>Predict performance of Miller field if 4 of 9 naturaly flowing wells are converted to gas lifted

>Provide BU and partners performance data to make production management decision

Study Methodology

>Match production & injection history of Miller field

> Integrate reservoirs, wells, and surface network in a completed system

>Tune well models against well test data>Generate vertical lift performance (VLP) curves

for all naturally flowing & gas lifted wells>Generate well IPR curves>Generate well performance curves based on VLP

& IPR curves>Predict field performance under different

operation strategies and system constraints

Miller Field Schematic

23

4

5

6

1

Multi-Reservoir Model Consideration

>Pressure data showed distinct trend in each compartment

>Geological description clearly supported a multi-tank system

>Single tank Mbal model was tested but history match was not as good

Miller Multi-Reservoir Mbal Model

History Matching: Southern Tank

Simulation

Application of Integrated Model

>Forecast production from every well, every tank, and the entire reservoir

>Forecast water injection to each tank>Evaluate the impact of converting certain wells

to gas lift at a specified time

Miller Integrated Model: Production Forecast

Gas Lift Well Performance Curves

Application of the Integrated Model

0 1 2 3 4 5 6 7 85400

5500

5600

5700

5800

5900

6000

6100

6200psig

Years

Tank Pressure, Reservoir by Case

MIL_V1 ( Southern co ) MIL_V1GL ( Southern co )

Monday, April 10, 2000 - 12:14 PM

Application of Integrated Model

0 1 2 3 4 5 6 7 860

61

62

63

64

65

66

67

68

69

70

71

72

73MMSTB

Years

Tank Oil, Cumulative by Case

MIL_V1 ( Central ) MIL_V1GL ( Central )

Monday, April 10, 2000 - 12:07 PM

Conclusion

>Converting four wells from naturaly flowing to gas lifted will be beneficial for the Miller field

>Cumulative oil production incremental is 1 MMB over 4 years

>Integrated study provided Miller Business Unit with technical results required for reservoir management decision