US energy giant ExxonMobil announced Wednesday that it was buying Canada\'s Celtic Exploration for Canadian $3.1 billion (US$3.14 billion) in a deal to expand its shale assets portfolio. \"ExxonMobil Canada will acquire 545,000 net acres (220,554 hectares) in the liquids-rich Montney shale, 104,000 net acres in the Duvernay shale and additional acreage in other areas of Alberta,\" Exxon\'s Canadian unit said in a statement. Exxon will assume Celtic\'s debt and pay Celtic shareholders $24.50 a share, which represents $2.6 billion dollars for the some 105.6 million shares in circulation. Celtic shareholders will receive shares of a new company that will hold assets not included in the Exxon deal, including acreage in British Columbia and Alberta and interests in oil and gas properties in Alberta. \"This acquisition will add significant liquids-rich resources to our existing North American unconventional portfolio,\" said Andrew Barry, president of ExxonMobil Canada. \"Our financial and technical strength will enable us to maximize resource value by leveraging the experience of ExxonMobil subsidiary XTO Energy, a leading US oil and natural gas producer which has expertise in developing tight gas, shale oil and gas and coal bed methane.\" The agreement was unanimously approved by Celtic\'s board of directors, but still requires approval by Celtic\'s shareholders and Canadian regulatory authorities. Shares in Dow member ExxonMobil were up 0.3 percent in pre-market trade.