SCOTS oil and gas tycoon Ian Suttie is ramping up his exposure to the UK North Sea with a $53 million (£32m) deal to buy a portfolio of assets east of Shetland.

The Aberdeen businessman's First Oil has agreed to buy the bulk of the North Sea estate amassed by Canada's Antrim Energy.

The assets include stakes in two producing fields and exploration acreage in an area where First Oil has become a significant player though acquisitions and exploration success.

Founded by Mr Suttie after he sold his Orwell oil services business to America's Weatherford International for around £115m in 2001, First Oil describes itself as the largest, private, UK owned company producing oil and gas in the North Sea.

The deal reflects Mr Suttie's enthusiasm for the North Sea as First Oil enters a key stage in its development.

The company is involved in one of the largest developments in UK waters through the 15% stake it holds in the giant Kraken heavy oil field east of Shetland.

The partners in the £4bn project, including Enquest and Cairn Energy, got the official go ahead for the development in November.

The deal with Antrim appears to be a bold move on First Oil's part, given the challenges the Calgary-based vendor has faced in recent months.

First Oil will acquire Antrim's 35.5% stake in the Causeway field, which has caused headaches.

Antrim said its board recommended the deal with First Oil following " an extensive process by the Company to secure additional viable financing needed to meet higher than expected capital costs to complete the Causeway development" as well as meeting other obligations.

The company said in a statement: "This process was hindered by production interruptions caused by platform shutdowns and ongoing delays in completion of the Causeway electric submersible pump and water injection facilities."

It added: "While ESP and water injection facilities are now expected to be operational by early Q2 2014, the operator has incurred further costs at Causeway and the Company has ongoing debt financing and oil swap obligations, which if not funded, could have resulted in the loss of the asset."

The deal will allow First Oil to increase its stake in the Cormorant East field to 16%, from 7.6%.

Antrim's share of current production from the two fields is around 800 barrels oil equivalent per day.

While First Oil did not comment on the acquisition, Mr Suttie likely feels the company has the resources to make the most of the assets.

With interests in around 30 North Sea fields, First Oil produced over 8000 boepd in the year to April.

This helped the company generate a record £82m cash from operations.

By contrast, Antrim 's experience underlines how difficult firms may find it to turn exploration interests into producing assets.

Antrim made a $135m loss in 2012.

This came after recording a $123m impairment charge against the value of its oil and gas interests. Antrim provided $54.7m against the valuation of the Fyne field and all of its related interests.

This followed a big increase in the projected capital costs of developing the field, using a Floating Production Storage and Offloading Vessel.

First Oil is not acquiring Antrim's stake in Fyne.

Antrim is working with Enegi Oil to develop a cheaper scheme to bring the field into production using unmanned buoys.

Antrim will retain its interest in the Erne exploration block in the UK North Sea and a licence off Ireland.

"Following the closing of the Transaction, Antrim expects to have approximately $17-$18m in working capital and no debt," the company told investors.

A chartered accountant by training, the 66-year-old Mr Suttie is known for keeping a low profile.

But he has now cemented his standing as one of Scotland's richest men in recent years, with a fortune estimated at £450m.

He has a variety of interests, including industries ranging from oil services to tidal energy and whisky through his First Tech investment vehicle.

First Oil will increase its exposure to the Kerlock exploration prospect to 26%, from 12.35%, through the deal with Antrim. It will also acquire a 30% stake in the Premier-operated exploration block 21/7b.

Antrim said that First Oil is set to assume "certain liabilities" as part of the deal, but did not give any details.

Shares in Antrim Energy closed up 15%, 0.62p, at 4.75p on the Aim market.