Shell in talks to buy BP stake in North Sea gas field - sources

* Shell is expanding Shearwater gas hub

* BP stake valued at around $250 mln -sources

By Ron Bousso

LONDON, April 24 (Reuters) - Royal Dutch Shell isin talks to buy BP's stake in the Shearwater oil and gasfield in the British North Sea for around $250 million, threeindustry sources told Reuters.

Shell, the field's operator, announced plans last year toexpand a gas hub around Shearwater, including the constructionof a new pipeline.

Shell has a 28 percent stake in Shearwater, BP holds 27.5percent and Exxon Mobil has the remaining 44.5 percent.

For BP, a sale would mark a step towards its target ofselling $5 to $6 billion of assets following its $10.5 billionpurchase of BHP's shale oil and gas portfolio in theUnited States last year.

Shell and BP, which both declined to comment, have heldtalks in recent weeks and are close to an agreement although thedeal could still fall through, two of the sources said.

Both Shell and BP have sold a large number of assets in theageing North Sea basin in recent years.

But at the same time they are investing heavily in newprojects in the region, particularly in the West of Shetlandsarea, as technology and cost cuts open new opportunities thatwere once considered too expensive.

Shearwater, located 225 kilometres (140 miles) east ofAberdeen, was discovered in 1988 and first developed in 2000.

At peak production, the gas export capacity of theShearwater hub is expected to be around 400 million standardcubic feet of gas a day, or roughly 70,000 barrels of oilequivalent per day, according to Shell.

(Reporting by Ron Bousso;Editing by Alexander Smith)