As part of a plan to grow its North American gas assets, Oil giant Royal Dutch Shell has bought the operations of closely-held natural gas exploration company East Resources in a $4.7 billion deal.

East Resources is one of the principal players in the Marcellus Shale, an exploration area that stretches across much of Ohio, West Virginia, Pennsylvania and New York.

Shell said it will acquire "substantially all the business" in return for cash payments to East Resources, its private equity investor Kohlberg Kravis Roberts & Co. and its advisors Jefferies & Co. The group said it will acquire 650,000 net acres of "highly contiguous, operated acreage" in the region and 1.05 million net acres of Marcellus Shale acreage overall.

There is an extensive medium term growth potential, as East Resources produces the correspondent of around 60 million cubic feet of gas, or 10,000 barrels of oil a day.

Also as part of the deal, Shell acquired 250,000 net acres of mineral rights in the Eagle Ford Shale region in South Texas.

"These undeveloped acreage positions are in the liquids rich window of the Eagle Ford play. Shell will be the operator in this highly contiguous acreage, and will be able to integrate these new assets into its existing South Texas operations”, the company said in a statement.

Shares in Shell fell 0.9% on the London Stock Exchange Friday, but outperformed rival BP, which dropped 3% as it continued its effort to halt the flow of oil from a leak in the Gulf of Mexico, which has so far cost the company $930 million.