As it looks to navigate a period of more modest energy prices, said on Friday that it would merge its Norwegian and gas operations with Det norske, a local player in that country.

The deal, with the much smaller oil company controlled by the Norwegian industrial giant Aker, appears to be a way for BP to slim down while keeping a hand in Norway, a key oil and gas producing nation. The new company, to be called Aker BP, will also use its new heft to take advantage of the weak energy environment to make targeted acquisitions.

“BP needs in this hypercompetitive world to think about different commercial models in different places,” Robert Dudley, the British company’s chief executive, told analysts on Friday during a conference call.

BP operates five oil and gas fields in Norwegian waters. There is the potential to expand some of these fields and extend their lives by finding new, usually smaller, oil and gas deposits around them and tying them into existing platforms.

But more efficient operations are required to make such opportunities profitable. Royal Dutch Shell recently said that it might leave up to 10 countries, where the size of its oil and gas operations are too small to make financial sense.

Oil giants like BP and Royal Dutch Shell acknowledge that smaller companies are often better at operating existing fields.

In 2003, for example, Apache, a medium-size company based in Houston, acquired part of the once-impressive Forties Oil Field in the British North Sea from BP, where production had declined by more than 90 percent from peak levels. Apache has made a success of the deal, raising production by about 20 percent.

BP’s exploration and production chief, Bernard Looney, said on the analysts’ call that Det norske’s lean approach would benefit the oil giant. The two sides expect the combined company, which now produces about 122,000 barrels a day, to double its output by the early 2020s.

Mr. Dudley suggested that other such deals might be in the offing. He has already created a separate subsidiary to operate BP’s shale oil and gas in the United States in an effort to operate in the cost-conscious manner of the American shale industry.

Like other oil companies, BP is also under pressure to bring costs in line with the sharply reduced revenues resulting from lower oil prices, which are now in the range of $50 a barrel. In the first quarter of this year, BP lost $1.2 billion on its once-lucrative oil and gas exploration and production operations.

BP has led the majors in selling assets because it also needed cash to pay for liabilities from its Deepwater Horizon in the Gulf of Mexico in 2010. The oil giant has raised $60 billion through disposals in recent years.

Under the deal, BP would gain a 30 percent shareholding in the Oslo-listed Aker BP and receive $140 million in cash. Aker would have a 40 percent stake, and the other shareholders 30 percent.