A letter of intent has been signed with Ensco UK which, subject to approvals, sees drilling taking place during the third and/or fourth quarters of this year.
The Colter discovery is adjacent to Wytch Farm, the largest onshore oil field in Europe, where more than 450mln barrels of oil have been produced.
A previous well at Colter encountered a 10.5 metre oil column and following seismic work in the area the new well will target a location up-dip from the original site.
United, via a farm-in option, has a 10% interest in the project and it estimates that its share of the costs to drill the well will be less than £1mln.
"We are delighted to see continuing progress on this exciting licence,” said Brian Larkin, United chief executive.
“The Colter Well will be drilled up-dip of an existing discovery in an established oil region.
“The addition of an excellent drilling partner, Ensco UK, will further strengthen our chances of success."
Larkin added: "This well is consistent with United's strategy of targeting near-term, low-risk development opportunities in Europe whilst utilising the industry experience of our management team to pursue higher-risk, high-impact opportunities in Africa and South America."