Offshore staff
LONDON -- Rockhopper Exploration has problems with the flow test on its 14/10-2 Sea Lion 1 well in the offshore North Falkland basin.
The test was performed over four perforated intervals totaling 77 m (252 ft) between 2,403 m (7,884 ft) and 2,566 m (8,418 ft) below the rig floor. On retrieval of the perforating guns, a gun misfire occurred - only the top two intervals were perforated, which meant that the lower two intervals did not contribute to the flow.
Following perforation, a small quantity of oil was produced into the tubing to clean the perforations and allow downhole oil sampling. The well was then shut in for around two hours to determine the initial reservoir pressure. Final recorded pressure was 3,385 psia at gauge depth (2,344 m, or 7,692 ft, below the rig floor) and was still building.
The well was then opened to flow through the 3 ½-in. test string, initially on a 24/64-in. choke, opened to a 64/64-in. choke during the flow period and reduced to 44/64-in. towards the end of the flow period to allow samples to be taken.
The well was flowed for around 18 hours without incident and for sustained periods of over 2,000 b/d up to a maximum of 2,304 b/d. Final flowing wellhead pressure was roughly 120 psia. A wax dissolver chemical was injected at the subsea test valve to mitigate wax build-up.
Rockhopper believes the flow rate was inhibited by incomplete perforation, waxing of the tubing string above 800 m (2,624 ft), increased viscosity of the oil as it cooled in the upper part of the test string, and a lack of specialist equipment. Without these constraints, the company believes a flow rate of 4,000 b/d could have been achieved.
Further, with a more optimal well location and horizontal well completions, significantly higher flow rates might be feasible from future production wells.
09/24/2010
