In the equity fund raise, arranged by broker SP Angel, the company is selling 3.3bn new shares at a price of 0.15p each.
The proceeds are earmarked for West Newton which Union Jack describes as a “highly accretive project”.
Specifically, the company envisages drilling and testing two additional appraisal wells and the acquisition and reprocessing of new seismic data.
Funds will also be used to drill an anticipated side-track well at Biscathorpe and to provide additional working capital.
"The board is delighted with the result of this successful fundraising,” said David Bramhill, Union Jack chairman.
Bramhill added: “The placing provides funding to progress the technically and financially compelling West Newton project under a planned two well drilling and testing programme for H1 2020 which we expect will add significantly to the earlier successes seen at the A-1 and A-2 hydrocarbon discoveries.
"We also have in place the funds required to complete a seismic acquisition programme over other structures that have been highlighted over the licence area, that we believe hold significant upside potential over and above the West Newton project.”
He noted that the company also has other material conventional assets, such as Biscathorpe and Wressle, that are expected to see activity over the coming months and those activities could prove to be transformational to the company.
"The directors are extremely confident about the future prospects for Union Jack and look forward to updating the market on developments at West Newton and our wider portfolio,” Bramhill highlighted.