In the acquisition, the company will take over the 545,000 net acres in the liquids-rich Montney shale, 104,000 net acres in the Duvernay shale and additional acreage in other areas of Alberta.

The shareholders of the Celtic Exploration will receive $24.91 (C$24.50) per share and half a share of a newly established company which will hold the assets include acreage in the Inga area in British Columbia, the Grande Cache area in Alberta and interests in oil and gas properties located in Karr, Alberta.

As per the estimation of Celtic Exploration on 31, December 2011, the current production of the to-be-acquired acreage is 72 million cubic feet per day of natural gas and 4,000 barrels per day of crude, condensate and natural gas liquids.

ExxonMobil Canada president Andrew Barry said the acquisition will add significant liquids-rich resources to the company’s existing North American unconventional portfolio.

"Our financial and technical strength will enable us to maximize resource value by leveraging the experience of ExxonMobil subsidiary XTO Energy, a leading U.S. oil and natural gas producer which has expertise in developing tight gas, shale oil and gas and coal bed methane," Barry said.

The agreement is subject to approval by Celtic Exploration’s shareholders and Canadian regulatory authorities.