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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 Gabon. Rabi. Thin Oil Rim Dev – 46 m
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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 Gabon Rabi 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 - 2500 GOR and rising - 60% WC and rising Gamba Shell Gabon Office Oil Terminal
“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.
“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:
“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
Smart Technology in Shell EP VALUE FUTURE PRESENT PAST RECOVERY ENHANCE Smart Fields DataMining / Artificial Intelligence / Neural Net / Expert System / Statistical Quality Control Surface/Wells/Subsurface Application / Workflow World’s First Online Integration Integrated Static Model e Business Online Dynamic Technology Evolution Modeling & Optimisation Tern Optimiser Smart Well Controller Dynacon FieldWare SMOC SOFS Shell Delta - P ACCELERATED Multivariable Shell Oil OIL Optimising Foundation Control Software 2003 TIME 90 95
“Project Specifics” Choke Valve Design & Selection • 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
CAO forRabi Smart Wells SG LAN NETWORK JB Shell Wide Web operator PI SERVER MULTI CORE CABLE I GAMBA Programmer P Central Station PT TT SIGNAL CABLE ALONG PIPELINE CHOKE VALVE Flow 5x Gathering Station Flow line length to Gathering Station 1 to 5 (a 6) Km. PT TT FT FV Gas Lift PT FIBRE OPTIC CABLE DCS +/ - 70x Wells WELL HEAD operator
“SWC Algorithm” Gas Lift Valve FC - 1 SP XVL-2 FC -2 Calc block Choke Valve MLD XVL-1 XFU-1 Inputs: THP, FLP, THT, FLT, Valve Position, dPk factor,etc. Ramp Rate 100 Gas Lift Choke 100 0 75
“SWC Well Stability” Rab-016 Scraping/Pigging
“SWC Benefit to Rabi” • Gains exceed • expectation +10% • GOR capped @ 3000 • CAO infrastructure • enabled rapid • intervention • Quality data enabled • weekly optimisation • Remote operation
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.