integrated reservoir modelling of the gannet a · pdf filegannet a historical reservoir...

Copyright of Shell U.K. Limited

Integrated reservoir modelling of the Gannet A field

1Mar 2011


CONTENTS

Introduction to Gannet A

Field history

Model build

Matching results

Key observations

2Mar 2011


GANNET A LOCATION MAP

3Mar 2011


GANNET A OVERVIEW

4Mar 2011

Deep marine turbidite sands.Upper Tay sandstone member (Eocene)

GOC: 7254 ft TVDSS – 52ft oil rim

200 MMstb oil rim200 Bscf solution gas300 Bscf free gas

40.5°API

Porosity: 32 %Permeability: 0.5 – 3.5 Darcy(1.5 D average)

Strong aquifer (N&E)

11 horizontal producers2 gas injectors


GANNET A HISTORY

5Mar 2011

Gas injection

Aquifer support

Initial

S

S N

N

Aquifer ingress from North and

East

Current


AVAILABLE SURVEILLANCE DATA

6Mar 2011

1993-2000

2000-2004

1993-2004

4D data PLTsSaturation logs

Production data

Pressures

2300

2400

2500

2600

2700

2800

2900

3000

3100

3200

3300

3400

01/01/1993

01/01/1994

01/01/1995

01/01/1996

01/01/1997

01/01/1998

01/01/1999

01/01/2000

01/01/2001

01/01/2002

01/01/2003

01/01/2004

01/01/2005

01/01/2006

01/01/2007

01/01/2008

01/01/2009

01/01/2010

01/01/2011

Pressure (psia))

Gannet A historical reservoir pressures

GANNETA02

GANNETA03

GANNETA07

GANNETA09S2

GANNETA10S1

GANNETA12

GANNETA14S1

GANNETA16

GANNETA18

GANNETA19

GANNETA20

GANNETA22

GANNETA23

Jan-93

Jan-94

Jan-95

Jan-96

Jan-97

Jan-98

Jan-99

Jan-00

Jan-01

Jan-02

Jan-03

Jan-04

Jan-05

Jan-06

Jan-07

Jan-08

Jan-09

Jan-10

Jan-11

GANNET A


MODELLING OBJECTIVES

� Growing mismatch between the modelled rate of water

encroachment and the logged producing contacts.

Modelling objectives:

� Improve the understanding of the aquifer encroachment and the

match to the 4D data.

� Better understand the current and future position of the gas cap.

� Re-assess the remaining potential of the field.

7Mar 2011


STATIC MODEL BUILD

8Mar 2011

20102005-9

EW

W E


STATIC AND DYNAMIC MODELS ITERATIONS

9Mar 2011

Static model build

Stochastic shale

distributionSimulation Production

matchProperty modelling

SimulationSaturation

logs match

Shale distribution alteration

pre-upscaling

Production, saturation logs and

water sweep match

Synthetic seismic

generation

Final match

Static & dynamic iterations

Dynamic iterations

4D surfaces

and maps match


INTEGRATION OF PRODUCTION AND 4D DATA IN THE SW

10Mar 2011

� Previous model showed more water sweep in the SW than the 4D data.

� Already no bottom aquifer influx in the previous model in this area, only

water expansion.

� Base reservoir pick challenging, picked alternative base, resulting in

less water in place.

Previous base pick Alternative base pick

EW EW


RESULTS: CUMULATIVE PRODUCTION MATCH

11Mar 2011


RESULTS: OVERALL 4D WATER SWEEP MAP MATCH

12Mar 2011

4D Data 93-042005-9 Modelled 4D synthetics 93-04

2010 Modelled 4Dsynthetics 93-04

Previous model New modelblue/ purple = water sweep

red = no water sweep


4D MATCH IN THE SOUTH EAST

13Mar 2011

4D Data

93-04

Synthetic

93-04

Good match near GA09S2 and

GA10S1 after integration of

dipmeter data.

Water Sweep

Map

Dark colours

represent water

sweep

Schematic view EW


GA19 SATURATION LOG PREDICTION MATCH

14Mar 2011

Dynamic modelQualitative saturation logs98 01 03 07 10 01 03 07 10

Saturation log acquired

in GA19 March 2010.

Model predicted

eastern water aquifer

ingress in the well up to

crest of the reservoir.


KEY OBSERVATIONS

15Mar 2011

� Mature field - plenty of surveillance.

� Integrated workflow:

� Much improved 4D match.

� Improved saturation logs match.

� Investigating potential infill wells and workovers.


ACKNOWLEDGEMENTS

16Mar 2011

� The authors would like to thank the Gannet A field partners:

Shell U.K. Limited and Esso Exploration and Production Limited

for allowing to publish.

� We would like to acknowledge other past and present Gannet A

team members for their contribution to the Gannet A modelling

project.


Q&A

17Mar 2011

integrated reservoir modelling of the gannet a · pdf filegannet a historical reservoir...

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