Nexen Announces Closing of Heavy Oil Asset Sale

CALGARY, ALBERTA -- (Marketwire) -- 07/22/10 -- Nexen Inc. announces that it has closed the sale of its heavy oil properties in Western Canada to Northern Blizzard Resources Inc. for $975 million (before closing adjustments and costs). These properties produced approximately 15,000 boe/d in the second quarter and had proved reserves of 39 million boe at December 31, 2009.

'We have achieved excellent value on the sale of these assets,' said Marvin Romanow, Nexen's President and CEO. 'With the completion of this sale, we have met our target of generating $1 billion of proceeds from the sale of non-core assets. We now expect to generate over $1.5 billion from all asset sales once we complete our disposition program which includes the sale of our interest in Canexus over the next 12 to 18 months.'

Nexen Inc. is an independent, Canadian-based global energy company, listed on the Toronto and New York stock exchanges under the symbol NXY. We are focused on three growth strategies: oil sands and unconventional gas in Western Canada and conventional exploration and development primarily in the North Sea, offshore West Africa and deep-water Gulf of Mexico. We add value for shareholders through successful full-cycle oil and gas exploration and development, and leadership in ethics, integrity, governance and environmental stewardship.

Forward-Looking Statements

Certain statements in this report constitute 'forward-looking statements' (within the meaning of the United States Private Securities Litigation Reform Act of 1995) or 'forward-looking information' (within the meaning of applicable Canadian securities legislation). Such statements or information (together 'forward-looking statements') are generally identifiable by the forward-looking terminology used such as 'anticipate', 'believe', 'intend', 'plan', 'expect', 'estimate', 'budget', 'outlook', 'forecast' or other similar words and include statements relating to or associated with individual wells, regions or projects. Any statements as to possible future crude oil, natural gas or chemicals prices, future production levels, future capital expenditures and their allocation to exploration and development activities, future earnings, future asset acquisitions or dispositions, future sources of funding for our capital program, future debt levels, availability of committed credit facilities, possible commerciality, development plans or capacity expansions, future ability to execute dispositions of assets or businesses, future sources of liquidity, cash flows and their uses, future drilling of new wells, ultimate recoverability of current and long-term assets, ultimate recoverability of reserves or resources, expected finding and development costs, expected operating costs, future cost recovery oil revenues from our Yemen operations, future demand for chemicals products, estimates on a per share basis, future foreign currency exchange rates, future expenditures and future allowances relating to environmental matters and dates by which certain areas will be developed, come on stream, or reach expected operating capacity and changes in any of the foregoing are forward-looking statements. Statements relating to 'reserves' or 'resources' are forward-looking statements, as they involve the implied assessment, based on estimates and assumptions that the reserves and resources described exist in the quantities predicted or estimated, and can be profitably produced in the future.

The forward-looking statements are subject to known and unknown risks and uncertainties and other factors which may cause actual results, levels of activity and achievements to differ materially from those expressed or implied by such statements. Such factors include, among others: market prices for oil and gas and chemicals products; our ability to explore, develop, produce, upgrade and transport crude oil and natural gas to markets; ultimate effectiveness of design or design modifications to facilities; the results of exploration and development drilling and related activities; volatility in energy trading markets; foreign-currency exchange rates; economic conditions in the countries and regions in which we carry on business; governmental actions including changes to taxes or royalties, changes in environmental and other laws and regulations; renegotiations of contracts; results of litigation, arbitration or regulatory proceedings; and political uncertainty, including actions by terrorists, insurgent or other groups, or other armed conflict, including conflict between states. The impact of any one risk, uncertainty or factor on a particular forward-looking statement is not determinable with certainty as these factors are interdependent, and management's future course of action would depend on our assessment of all information at that time.

Although we believe that the expectations conveyed by the forward-looking statements are reasonable based on information available to us on the date such forward-looking statements were made, no assurances can be given as to future results, levels of activity and achievements. Undue reliance should not be placed on the statements contained herein, which are made as of the date hereof and, except as required by law, Nexen undertakes no obligation to update publicly or revise any forward-looking statements, whether as a result of new information, future events or otherwise. The forward-looking statements contained herein are expressly qualified by this cautionary statement. Readers should also refer to Items 1A and 7A in our 2009 Annual Report on Form 10-K for further discussion of the risk factors.

Cautionary Note to US Investors

In this disclosure, we may refer to 'recoverable reserves', 'recoverable resources' and 'recoverable contingent resources' which are inherently more uncertain than proved reserves or probable reserves. These terms are not used in our filings with the SEC. Our reserves and related performance measures represent our working interest before royalties, unless otherwise indicated. Please refer to our Annual Report on Form 10-K available from us or the SEC for further reserve disclosure.

Cautionary Note to Canadian Investors

Nexen is an SEC registrant and a voluntary Form 10-K (and related forms) filer. Therefore, our reserves estimates and securities regulatory disclosures follow SEC requirements. In Canada, National Instrument 51-101-Standards of Disclosure for Oil and Gas Activities (NI 51-101) prescribes that Canadian companies follow certain standards for the preparation and disclosure of reserves and related information. Nexen's reserves disclosures are made in reliance upon exemptions granted to it by Canadian securities regulators from certain requirements of NI 51-101 which permits us to:

--  prepare our reserves estimates and related disclosures in accordance
    with SEC disclosure requirements, generally accepted industry practices
    in the US and the Canadian Oil and Gas Evaluation Handbook (COGE
    Handbook) standards modified to reflect SEC requirements;
--  substitute those SEC disclosures for much of the annual disclosure
    required by NI 51-101; and
--  rely upon internally-generated reserves estimates and the Standardized
    Measure of Discounted Future Net Cash Flows and Changes Therein,
    included in the Supplementary Financial Information, without the
    requirement to have those estimates evaluated or audited by independent
    qualified reserves consultants.

As a result of these exemptions, Nexen's disclosures may differ from other Canadian companies and Canadian investors should note the following fundamental differences in reserves estimates and related disclosures contained in the Form 10-K:

--  SEC registrants apply SEC reserves definitions and prepare their
    reserves estimates in accordance with SEC requirements and generally
    accepted industry practices in the US whereas NI 51-101 requires
    adherence to the definitions and standards promulgated by the COGE
    Handbook;
--  the SEC's technical rules in estimating reserves differ from NI 51-101
    in areas such as the use of reliable technology, aerial extent around a
    drilled location, quantities below the lowest known oil and quantities
    across an undrilled fault block;
--  the SEC mandates disclosure of proved reserves and the Standardized
    Measure of Discounted Future Net Cash Flows and Changes Therein
    calculated using the year's 12-month average prices and costs only
    whereas NI 51-101 requires disclosure of reserves and related future net
    revenues using forecast prices;
--  the SEC mandates disclosure of reserves by geographic area only whereas
    NI 51-101 requires disclosure of more reserve categories and product
    types;
--  the SEC prescribes certain information about proved and probable
    undeveloped reserves and future developments costs whereas NI 51-101
    requirements are different;
--  the SEC does not require disclosure of finding and development (F&D)
    costs per boe of proved reserves additions whereas NI 51-101 requires
    that various F&D costs per boe and additional information be disclosed;
--  the SEC leaves the engagement of independent qualified reserves
    consultants to the discretion of a company's board of directors whereas
    NI 51-101 requires issuers to engage such evaluators;
--  the SEC does not allow proved and probable reserves to be aggregated
    whereas NI 51-101 requires issuers disclose such; and
--  the reserves disclosures in this document have not been reviewed by the
    independent qualified reserves consultants whereas NI 51-101 requires
    them to review it.

The foregoing is a general description of the principal differences only. The differences between SEC requirements and NI 51-101 may be material.

NI 51-101 requires that we make the following disclosures:

--  we use oil equivalents (boe) to express quantities of natural gas and
    crude oil in a common unit. A conversion ratio of 6 mcf of natural gas
    to 1 barrel of oil is used. Boe may be misleading, particularly if used
    in isolation. The conversion ratio is based on an energy equivalency
    conversion method primarily applicable at the burner tip and does not
    represent a value equivalency at the wellhead; and
--  because reserves data are based on judgments regarding future events
    actual results will vary and the variations may be material. Variations
    as a result of future events are expected to be consistent with the fact
    that reserves are categorized according to the probability of their
    recovery.

Resources

Nexen's estimates of contingent resources are based on definitions set out in the Canadian Oil and Gas Evaluation Handbook which generally describe contingent resources as those quantities of petroleum estimated, as of a given date, to be potentially recoverable from known accumulations using established technology or technology under development, but which are not currently considered to be commercially recoverable due to one or more contingencies. Such contingencies may include, but are not limited to, factors such as economic, legal, environmental, political and regulatory matters or a lack of markets. Specific contingencies precluding these contingent resources being classified as reserves include but are not limited to: future drilling program results, drilling and completions optimization, stakeholder and regulatory approval of future drilling and infrastructure plans, access to required infrastructure, economic fiscal terms, a lower level of delineation, the absence of regulatory approvals, detailed design estimates and near-term development plans, and general uncertainties associated with this early stage of evaluation. The estimated range of contingent resources reflects conservative and optimistic likelihoods of recovery. However, there is no certainty that it will be commercially viable to produce any portion of these contingent resources.

Nexen's estimates of discovered resources (equivalent to discovered petroleum initially-in-place) are based on definitions set out in the Canadian Oil and Gas Evaluation Handbook which generally describe discovered resources as those quantities of petroleum estimated, as of a given date, to be contained in known accumulations prior to production. Discovered resources do not represent recoverable volumes. We disclose additional information regarding resource estimates in accordance with NI 51-101. These disclosures can be found on our website and on SEDAR.

Cautionary statement: In the case of discovered resources or a subcategory of discovered resources other than reserves, there is no certainty that it will be commercially viable to produce any portion of the resources. In the case of undiscovered resources or a subcategory of undiscovered resources, there is no certainty that any portion of the resources will be discovered. If discovered, there is no certainty that it will be commercially viable to produce any portion of the resources.

Contacts:

Investor Relations Inquiries:

Michael J. Harris, CA

Vice President, Investor Relations

(403) 699-4688


Tim Chatten, P.Eng

Analyst, Investor Relations

(403) 699-4244


Media and General Inquiries:

Pierre Alvarez

Vice President, Corporate Relations

(403) 699-5560


Nexen Inc.

801 - 7th Ave SW

Calgary, Alberta, Canada T2P 3P7
www.nexeninc.com