Union Jack Oil PLC (AIM:UJO) told investors that work to install a downhole jet pump and recomplete the Wressle well has been successfully concluded.
Operations to upgrade surface facilities are now in the final stages.
The Wressle well is now expected to resume production in the week commencing 23 October 2023.
"I am pleased with the operations being progressed at Wressle,” said David Bramhill, Union Jack executive chair.
"The capital expenditure incurred in the completion of these works is comfortably funded from existing cash balances and will be offset against the Energy Profit Levy Tax at a rate of 129%.
"I look forward to updating the market once stabilised production has been achieved."
Union Jack owns a 40% interest in the UK onshore field, located in Lincolnshire.