Rising costs of capital intensive projects such as shale oil and deep water drilling mean that opportunities are opening up for investors looking to buy mature fields which majors are quitting earlier than in recent years, Bob Maguire, head of Carlyle International Energy Partners (CIEP) told Reuters.

"It means that capital budgets are stretched -- particularly with commodity prices coming down -- and asset sales are an important source of cash," Maguire said in an interview. 

Brent crude has tumbled from above $115 per barrel in June to a four-year low around $82 per barrel on Wednesday , while other commodities such as gold have also fallen sharply.

"As a result, companies are looking at parts of their portfolios that in other times they would not be selling."

Maguire left advisory firm Perella Weinberg to join CIEP, part of Carlyle's $28 billion (17.62 billion British pounds) global energy and real estate platform, Reuters reported in February.

He is known in the industry for his work on large energy deals such as BP's acquisition of Arco and Shell's purchase of Enterprise.

Chinese companies, which were typically aggressive in moving into areas such as Africa, are also less active, Maguire said.

"The fact that whole categories of buyers -- the major oil companies,  NOCs, utilities and, albeit temporarily, the Chinese oil companies have stepped out of the market creates something of a buyers' market."

Mature oil projects in the North Sea and West Africa present some of the best opportunities for acquisitions in the energy sector, Maguire said, while oil majors focus on expensive new exploration and production.

"The industry is in the build phase of a lot of new basins. The majors are focused on large-scale resource plays in places such as Brazil, West Africa and the Arctic," he said.

The fund has only has a mandate to invest in assets outside the United States, with separate funds investing within the United States.

CIEP jointly owns Varo Energy with Vitol, the world's largest oil trader.

Varo bought 45 percent in Germany's 260,000 barrel per day Bayernoil refinery from Austrian group OMV (>> OMV AG), and aims to build downstream assets in Europe.

Varo already owns the 68,000 bpd Swiss refinery Cressier and storage facilities in the port of Antwerp and in Germany.

(Reporting by Simon Falush, editing by David Evans)

Stocks treated in this article : OMV AG, The Carlyle Group LP