ExxonMobil Canada Acquires Celtic Exploration Ltd., Including Liquids-Rich Montney Shale Acreage

  ExxonMobil Canada Acquires Celtic Exploration Ltd., Including Liquids-Rich
  Montney Shale Acreage

  *Agreement includes 649,000 net acres in the Montney and Duvernay shales in
    Alberta

Business Wire

CALGARY, Alberta -- October 17, 2012

ExxonMobil Canada today announced an agreement with Celtic Exploration Ltd.
(“Celtic”) under which an ExxonMobil Canada affiliate will acquire Celtic.

Under the terms of the agreement, ExxonMobil Canada will acquire 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.

Current production of the acreage to be acquired is 72 million cubic feet per
day of natural gas and 4,000 barrels per day of crude, condensate and natural
gas liquids. The assets were estimated by Calgary-based Celtic Exploration at
December 31, 2011 to include an estimated 128 million oil equivalent barrels
of proved plus probable reserves, of which 24 percent are crude, condensate
and natural gas liquids and 76 percent natural gas.

Approximately 60 employees at Celtic Exploration will be given the opportunity
to transition to ExxonMobil employment.

Shareholders of Celtic Exploration will receive C$24.50 per share and half a
share of a newly established company which will hold assets not included in
the agreement with ExxonMobil Canada. These 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.

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

“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 U.S. oil and natural gas producer which has expertise in
developing tight gas, shale oil and gas and coal bed methane.”

ExxonMobil Canada, a subsidiary of Exxon Mobil Corporation (NYSE:XOM), has a
long history in Canada that dates back to the 1940s. The company is a leader
in the Atlantic Canada offshore, where it operates the Sable project in Nova
Scotia, is lead owner of the Hibernia project in Newfoundland and Labrador,
where it is developing the Hebron project. ExxonMobil Canada has additional
assets in Western and Northern Canada.

ExxonMobil’s Canadian affiliate, Imperial Oil Limited, is not a party to the
transaction, but may elect to participate at a later date through its existing
agreement with ExxonMobil Canada that provides for up to equal participation
in new Canadian upstream opportunities. Imperial Oil Limited has advised that
it is currently evaluating this opportunity.

CAUTIONARY NOTE

Business plans, estimates, and other statements of future events or conditions
in this release are forward-looking statements. Actual results, including
closing of the proposed transaction, post-closing ownership structure,
production rates, and resource recoveries may differ materially due to a
number of factors including: approval of the transaction by Celtic
shareholders; approval of the transaction by regulatory authorities and any
conditions to such approval; the satisfaction of other conditions precedent
provided in the acquisition agreements; changes in market prices and other
factors affecting the supply of and demand for oil, natural gas, condensate,
and natural gas liquids; changes in law or government regulation; the outcome
of commercial negotiations; reservoir performance; timely completion of
development projects; unforeseen technical or operating factors; and other
factors discussed under the heading “Factors affecting future results” on the
“Investors” page of ExxonMobil’s website at exxonmobil.com and in Item 1A of
ExxonMobil’s most recent annual report on Form 10-K. We assume no duty to
update these statements as of any future date. Proved plus probable reserve
estimates quoted in this release were determined by Celtic using definitions
applicable to Canadian reporting companies and may not be the same as proved
or probable reserves as determined under U.S. SEC definitions. This release
does not constitute an offer to purchase or a solicitation of an offer to sell
any security, and does not constitute a solicitation of votes or proxies with
respect to any security.

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