1. Gas Coning Control and Gaslift Stabilisation in Shell GabonBy
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

2. Shell Gabon Rabi Gamba Thin Oil Rim Dev – 46 m Some 200 + Wells
Horizontal Slotted Liner
Nat.Prod., GL, Wtr & Gas Inj.
5 Gathering Stations
One Central Station
Early 2001 Production fig.-
- 90kbpd, 20% decline/yr
GOR and rising
- 60% WC and rising
Gamba
Shell Gabon Office
Oil Terminal

3. “Rabi Dumb Well” Wellhead measurements are all local
Production choke control by fixed bean (expressed in ~n*8/64th inch)
Operator visits well by car
If bean too small: well dies, seen by change of THP
If bean too large: well “cones gas”, seen by change of THP and THT/FLT
After a start-up a well needs smaller beans as time progresses
Pigging and scraping for wax removal at ~2 d intervals.

4. “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:

5. “Project Objectives”
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

6. Smart Technology in Shell EP
VALUE
PAST
PRESENT
FUTURE
ENHANCE
RECOVERY
Smart
Fields
DataMining
/ Artificial Intelligence /
Neural Net / Expert System /
Statistical Quality Control
Surface/Wells/Subsurface
Application / Workflow
World’s First Online
Integrated Static Model
Integration
e Business
Online Dynamic
Technology Evolution
Modeling
&
Optimisation
Tern
Optimiser
Smart Well
Controller
Dynacon
FieldWare
SMOC
SOFS
Shell
Delta - P
ACCELERATED
OIL
Shell Oil
Multivariable
Foundation
Optimising
Software
Control
2003
TIME

7. “Project Specifics” Choke Valve Design & Selection Control System
  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
Control System
Delta-P, Delta-T measurements for coning detection and well instability
Leverage existing eqpt, contracts for fast tracking
  Minimal maintenance due to the remoteness of Rabi

8. CAO for Rabi Smart Wells
SG LAN NETWORK JB
Shell Wide Web
operator
PI SERVER
MULTI
CORE
CABLE I
Central Station
GAMBA Programmer P PT TT
SIGNAL CABLE ALONG PIPELINE
CHOKE
Flow
VALVE
5x Gathering Station
Flow line length to Gathering Station
1 to 5 (a 6) Km. TT PT FT FV
Gas Lift PT
FIBRE OPTIC CABLE
DCS +/ -
70x Wells
WELL
HEAD
operator

9. “Rabi Smart Well Controller”

10. “SWC Multiphase Flowmeter”

11. “SWC Algorithm” Inputs: THP, FLP, THT, FLT, FC - 1 SP XVL-2 FC -2
Gas Lift Valve
Calc block
FC - 1 SP
XVL-2
FC -2
XVL-1
MLD
XFU-1
Choke Valve
Inputs: THP, FLP, THT, FLT,
Valve Position, dPk factor,etc.
Ramp Rate
100
Choke
Gas Lift 75
100

12. “SWC Automatic Sequencing”

13. “SWC Auto Start-Up”

14. Rab-016 Scraping/Pigging
“SWC Well Stability”
Rab-016 Scraping/Pigging

15. “SWC Benefit to Rabi” Gains exceed expectation +10% GOR capped @ 3000
CAO infrastructure
enabled rapid
intervention
Quality data enabled
weekly optimisation
Remote operation

16. 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.

17. “Rabi Smart Team”