Some 100mln new shares are being issued at a price of 2p each, a 5% discount to Tuesday’s closing price in London.
“This placing is intended for opportunistic investment to help deliver the company's stated goal of consolidating and expanding its asset base in the Weald Basin,” the company said in a statement.
It follows the recent £10.5mln raise - £5.5mln on June 15 and £5mln on July 2 - which were intended to deliver sufficient working capital for its core projects over the next 18 months.
UKOG is the largest London-listed stakeholder in the Horse Hill oil project, located about 5 miles from Gatwick Airport, with a 32% interest.
The spotlight is presently on the project amid a potentially pivotal new work programme.
Last month, the programme was greenlighted by regulator The UK Oil and Gas Authority (OGA) – clearing a 150-day extended production well test, to be followed by new well drilling.
Specifically, the programme is a follow up to the 2016 testing, which saw aggregate oil flows at a rate of 1,688 barrels per day over short periods (three 30-90 hour tests).
The aim of the work is to prove commerciality ahead of a possible field start-up next year.