Mosman Oil and Gas Ltd (LON:MSMN) told investors it started the workover of the Duff-2 well at the Greater Stanley project in Texas.
The Duff-2 well will be recompleted in a zone which is in production at the adjacent Stanley field.
Gross costs for the programme are estimated at US$50,000, of which US$20,000 will be covered by Mosman for its share.
Mosman recently acquired an additional 20% in the Duff lease, part of the Greater Stanley project, increasing its stake to 40%.
The lease covers 36 acres. It has two currently produces around 160-180 barrels per month.