Abstract

The oil producing subsea wells on the Troll field offshore Norway have become more complex with advancing technology. To maximise the drainage of the thin oil layer, horizontal precision drilling in combination with multilateral technology have increased productivity in the wells. In the lower completion swellable elastomer packers and inflow control devices in sand screens delay gas breakthrough and water coning. Natural gas lift from the gas cap is used to lift the wells. Two well branches in the reservoir can be shut in separately using flow control valves, avoiding costly equipment and interventions. Several downhole gauges in the well contribute to optimising production and oil recovery. A dual branch and dual zone hydraulically controlled completion has been installed with pressure and temperature monitoring, and is the most complex completion installed on the field. The well contains an additional hydraulic controlled oil zone compared to current Troll completions. Today the wells are still complex, but less hardware is installed. More zone control is the trend for future developments.

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