Shell Global Solutions Gas Coning Control and Gaslift Stabilisation in Shell Gabon By Aat Eken, Shell Global Solutions, Rijswijk NL Mike Harper, Shell

Shell Global Solutions

Shell Global Solutions

Gas Coning Control and Gaslift Stabilisation in Shell Gabon By

Aat Eken, Shell Global Solutions, Rijswijk NL

Mike Harper, Shell Gabon, Rabi

Cor Koster, Shell Gabon, Gamba

Azmi Mohd. Noor, Shell Global Solutions, Kuala Lumpur, Malaysia

Shell Global Solutions 2

ASME/API/ISO Fall 2003 Gas-Lift Workshop, 21st – 24th Oct, Kuala Lumpur

Shell Gabon

Rabi

GambaShell Gabon OfficeOil Terminal

Thin Oil Rim Dev – 46 mSome 200 + WellsHorizontal Slotted LinerNat.Prod., GL, Wtr & Gas Inj.5 Gathering StationsOne Central StationEarly 2001 Production fig.- - 90kbpd, 20% decline/yr - 2500 GOR and rising - 60% WC and rising



““Rabi Dumb Well”Rabi Dumb Well”• Wellhead measurements are all local

• Pigging and scraping for wax removal at ~2 d intervals.

• After a start-up a well needs smaller beans as time progresses

• If bean too large: well “cones gas”, seen by change of THP and THT/FLT

• If bean too small: well dies, seen by change of THP

• Operator visits well by car

• Production choke control by fixed bean (expressed in ~n*8/64th inch)



““Case for Action”Case for Action”

Problem: Thin oil rim with gas cap, causing gas break through and coning.

Declining at a rate of some 20% per year.Consequence:Consequence:

Rabi Production Performance

40

50

60

70

80

90

100

110

120

130Ja

n-00

Feb-

00

Mar

-00

Apr

-00

May

-00

Jun-

00

Jul-0

0

Aug

-00

Sep-

00

Oct

-00

Nov

-00

Dec

-00

Jan-

01

Feb-

01

Mar

-01

Apr

-01

May

-01

Jun-

01

Jul-0

1

Aug

-01

Sep-

01

Oct

-01

Nov

-01

Dec

-01

Jan-

02

Feb-

02

Mar

-02

Apr

-02

May

-02

Jun-

02

Jul-0

2

Aug

-02

Net

pro

duct

ion

rate

(b/d

)

Base R186

R187 R188

R189 R190

R191



• Automated well control via an algorithm control loop to arrest gas coning

• CAO network, providing remote monitoring and control • Provide live well data onto the SWW

• Fast track project to arrest rapid decline (20% per year)

• Technology to be maintainable • Provide the basic infrastructure to allow remote control of Rabi gathering stations

““Project Objectives”Project Objectives”



SOFSShell Oil

FoundationSoftware

Dynacon

Tern Optimiser

AC

CE

LE

RA

TE

DO

ILE

NH

AN

CE

RE

CO

VE

RY

VALUE

TIME

PAST PRESENT FUTURE

90 95 2003

SMOCShell

MultivariableOptimising

Control

World’s First Online Integrated Static Model

Smart WellController

Online Dynamic Modeling &

Optimisation

FieldWare

Delta-P

Surface/Wells/Subsurface Application / Workflow

Integration

DataMining / Artificial Intelligence / Neural Net / Expert System /

Statistical Quality Control

SmartFields

e Busin

ess

Technolo

gy Evolu

tion

Smart Technology in Shell EP



• Interchangeable trims so that standard body sizes could be deployed

• Given high GOR wells, chokes used as in the NAM fields were chosen

• Linear characteristics and high rangeability for controllability

• Easier identification of bean size equivalent for choke trim sizes

• Minimal maintenance due to the remoteness of Rabi

“Project Specifics”

Choke Valve Design & Selection

Control System

• Delta-P, Delta-T measurements for coning detection and well instability

• Leverage existing eqpt, contracts for fast tracking



JB

MULTICORECABLE I

P

PT

CHOKESIGNAL CABLE ALONG PIPELINE

VALVEFlow

Flow line length to Gathering Station1 to 5 (a 6) Km.PT

PT

WELLHEAD

TT

Gas Lift

FT FV

DCS

operator

operator

FIBRE OPTIC CABLE

PI SERVER

GAMBA Programmer

SG LAN NETWORK

Central Station

5x Gathering Station

+/-70x Wells

TT

Shell Wide Web

CAO forCAO for Rabi Smart WellsRabi Smart Wells



““Rabi Smart Well Controller”Rabi Smart Well Controller”



““SWC Multiphase Flowmeter”SWC Multiphase Flowmeter”



Calc block

Inputs: THP, FLP, THT, FLT,

Valve Position, dPk factor,etc.

FC - 1 SP

Ramp Rate

FC -2Gas Lift

ValveXVL-2

XVL-1 MLD XFU-1 Choke Valve

0 75 100

100

Gas

Lift

Choke

““SWC Algorithm”SWC Algorithm”



time

Choke position

stop

Max start choke

Ramp to optimal SP

Normal operation

time

L/ G SP

Max lift gas

Ramp down to min lift gas

Hold Q

THP criterion

CHP reached

““SWC Automatic Sequencing”SWC Automatic Sequencing”



RAB016

RAB016 Calc flow Q

RAB016 Gaslift Flow UncompRAB016 Wellhead Pressure

RAB016 From Choke Valve

RAB016 CONING MEAS RAB016 From controller

RAB016 Calc flow Q

03/06/2002 12:00:00 06/06/2002 12:00:003.00 Day(s)

50-FC-0161.PV

%

50-FC-0162.PV

MMSCF/D

50-PI-0161.PV

Barg

50-XV-0161.PV

%

50-XAV-0167.CPV

%

50-FC-0161.MV

%

50-FC-0161.SV

% 10

20

30

40

50

60

70

80

90

0

100

0

2

0

50

0

100

0

0.5

0

100

0

10075.41

2.6667E-03

31.576

69.66

No Data

51.57

75.

50-FC-0161.PV

%

50-FC-0162.PV

MMSCF/D

50-PI-0161.PV

Barg

50-XV-0161.PV

%

50-XAV-0167.CPV

%

50-FC-0161.MV

%

50-FC-0161.SV

%

““SWC Auto Start-Up”SWC Auto Start-Up”



Pressures (barg)

RAB016 Casing Pressure

RAB016 Wellhead Pressure

RAB016 Flowline Pressure

RAB016 DIFF PRESSURE

09/06/02 15:30:14 10/06/02 15:30:1424.00 Hour(s)

40.0

60.0

0.0

100.0 48.5

37.9

15.8

22.11

34.017.8

13.8

3.97

10/06/02 09:47:22

RAB016 TrendsTemperatures (deg. C)

RAB016 Wellhead temperatur

RAB016 Flowline temperatur

RAB016 DIFF TEMPERATURE

09/06/02 15:32:09 10/06/02 15:32:0924.00 Hour(s)

20.0

40.0

60.0

0.0

100.0 36.3

34.7

1.42

Calc. Q and Choke

RAB016 Calc flow Q

RAB016 To Choke Valve

RAB016 From Choke Valve

09/06/02 15:32:09 10/06/02 15:32:0924.00 Hour(s)

20

40

60

0

100 75

45

59

Gaslift

RAB016 Gaslift Flow Comp

RAB016 Gaslift Control Val

09/06/02 15:32:09 10/06/02 15:32:0924.00 Hour(s)

MSCF/D

%

0.500

1.000

1.500

0.000

2.000

0

100 0.003

0

MSCF/D

%

Wells OverviewGraphic

Rab-016 Scraping/Pigging

““SWC Well Stability”SWC Well Stability”



0

20,000

40,000

60,000

80,000

100,000

Jan-01 Fe

b-01

Mar-01

Apr-01 Ma

y-01

Jun-01 Jul-

01 Aug-01

Sep-01

Oct-01 No

v-01

Dec-01

Jan-02 Fe

b-02

Mar-02

Apr-02 Ma

y-02

Jun-02 Jul-

02 Aug-02

Sep-02

Oct-02 No

v-02

1,000

2,000

3,000

4,000

5,000

6,000

FGOR Oil Rate

bbl/d FGOR scf/bbl

• Gains exceed expectation +10%

• GOR capped @ 3000

• Quality data enabled weekly optimisation

• CAO infrastructure enabled rapid intervention

• Remote operation

““SWC Benefit to Rabi”SWC Benefit to Rabi”



Conclusions

• Production of oil from thin oil rims lead to gas coning

• Limited gas coning helps optimise production

• Uncontrolled gas coning leads to rapid depletion of the gas cap and strong production decline• Better production information and better well stability through ConeControl assists the production optimisation team in their task to produce the oil field in the best possible way.



““Rabi Smart Team”Rabi Smart Team”

Documents

Shell Global Solutions Gas Coning Control and Gaslift Stabilisation in Shell Gabon By Aat Eken, Shell Global Solutions, Rijswijk NL Mike Harper, Shell