ASCO aims to double in size over the next four years after increasing profits by 21% in 2012, helped by booming investment in the North Sea.

The Aberdeen-based oil and gas logistics group achieved earnings before interest, tax, depreciation and amortisation of £36.5 million compared with £30.1m in the preceding year.

The company said the year featured a strong performance by its European arm on the back of greater activity on the United Kingdom Continental Shelf. Oil and gas firms are trying to maximise production in the area to cash in on strong demand for energy in places like China.

ASCO, which offers services ranging from operating rig supply boats to managing warehouses, retained major contracts with firms like Nexen and Enquest. Both are working on bringing new North Sea fields into production.

The company increased its presence in the North Sea market last year through the acquisition of the NSL Training Services business in Aberdeen.

Chief executive Derek Smith said the company would consider buying more businesses to expand the range of services it provides in the North Sea. He added: "The North Sea will always be a core market."

ASCO employs 850 people in north east Scotland out of a global total of 2100.

Following reports skills shortages may hinder oil and gas firms efforts to expand in the North Sea, Mr Smith said ASCO has recruited around 15 former soldiers to help it keep pace with the growth in activity in the area.

Mr Smith said ASCO also made good progress with its efforts to grow in overseas markets last year, the first under the ownership of Doughty Hanson.

The private equity business bought ASCO for around £250m in December 2011, with a view to helping it expand in international oil and gas markets.

ASCO bought the Oniqua software business in Australia last year, which increased its exposure to the key Australasian market. The deal allowed ASCO to widen its service range to include helping firms manage their inventories.

The company also bought three firms active in the oil sands market in Canada.

Executive chairman Billy Allan said: "The development of shale oil and gas will continue to have an impact on the industry and we are monitoring these developments closely with a firm eye on exploiting these opportunities both at home and abroad."

Mr Allan said directors' ultimate aim is to double the size of the business over the next four years.

ASCO increased turnover by 11.2% to £678.3m in 2012, from £610.2m in 2011. It made £435,000 pre-tax profit net of £18.4m interest charges.