North Sea explorer Ithaca Energy fell in early trading on Monday after the firm said one of its wells was blocked and not producing oil.
Shares dropped almost 9% after the company said only three of its four production wells on the Athena field were flowing due to a suspected downhole restriction in one of them.
Ithaca said testing had shown that there were no issues with the integrity of the well or performance of the reservoir in the area of the field drained by the well.
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The gross production potential of the restricted well is approximately 5,000 barrels of oil per day, representing 1,125 barrels net to Ithaca.
"The changeable flow rates achieved from the well during testing indicate that the restriction is likely attributable to a blockage in the production tubing located within the well," the firm said.
"Diagnostic work is ongoing to identify the nature of the blockage and the most effective course of action for eliminating it."
The company is currently evaluating remote intervention methods to restore the restricted well to its full
production potential.
This includes use of the existing facilities to hydraulically remove the obstruction.
However, if these methods were not successful, Ithaca said a rig-based workover could be required, which would mean waiting until the end of this year.
