**Exhibit 23.4**

 

**DEGOLYERAND MACNAUGHTON**

5001 SPRING VALLEY ROAD

SUITE 800 EAST 

DALLAS, TEXAS 75244

 

February 2, 2010

 

NexenInc.

801-7th Avenue S.W.

Calgary,AB 

T2P3P7

 

**Attention: Reserves Review Committee of the Board ofDirectors of Nexen Inc.**

 

**Re:****          ****DeGolyerand MacNaughton - Report of Third Party for certain Nigeria properties withinterests owned by Nexen Inc.**

 

Ladiesand Gentlemen:

 

Pursuant to your request, we have conducted an independent evaluationof Nexen Inc.’s (Nexen) proved and probable oil, condensate, natural gasliquids (NGL), and natural gas reserves, as of December 31, 2009, forcertain fields owned by Nexen in Nigeria. Nexen has represented that theseproperties account for less than 5 percent on an equivalent barrel basis of itsproved reserves as of December 31, 2009, and that its reserves estimateshave been prepared in accordance with the United States Securities and ExchangeCommission (SEC) definitions. We have reviewed information provided to us byNexen that it represents to be its estimates of the reserves, as of December 31,2009, for the same properties as those which we evaluated.

 

Reserves included herein are expressed as reserves as represented byNexen. Gross reserves are defined as the total estimated petroleum to beproduced from these properties after December 31, 2009. Working interestreserves are defined as that portion of the gross reserves attributable to theinterests owned by Nexen after deducting all interests owned by others. Netreserves are defined as working interest reserves after deductions forroyalties.

 

Estimates of oil, condensate, and NGL (collectively, Liquids), andnatural gas should be regarded only as estimates that may change as furtherproduction history and additional

 

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information become available. Not only are such reserves estimatesbased on that information which is currently available, but such estimates arealso subject to the uncertainties inherent in the application of judgmentalfactors in interpreting such information.

 

Data used in this evaluationwere obtained from reviews with Nexen personnel, Nexen files, from records onfile with the appropriate regulatory agencies, and from public sources. In thepreparation of this report we have relied, without independent verification,upon such information furnished by Nexen with respect to property interests,production from such properties, current costs of operation and development,prices for production, agreements relating to current and future operations andsale of production, and various other information and data that were acceptedas represented. Furthermore, if in the course of our examination something cameto our attention which brought into question the validity or sufficiency of anyof such information or data, we did not rely on such information or data untilwe had satisfactorily resolved our questions relating thereto or hadindependently verified such information or data. A field examination of theproperties was not considered necessary for the purposes of this report.

 

**Methodology and Procedures**

 

The process of estimating reserves requires complexjudgments and decision-making based on available geological, geophysical,engineering, and economic data. To estimate the economically recoverable oiland natural gas reserves and related future net cash flows, we consider manyfactors and make assumptions including:

** **

**·****                 **expectedreservoir characteristics based on geological, geophysical, and engineering assessments;

·                   future production ratesbased on historical performance and expected future operating and investmentactivities;

·                   future oil and gas pricesand quality differentials;

·                   assumed effects ofregulation by governmental agencies; and

·                   future development andoperating costs.

 

Our estimate is preparedusing standard geological and engineering methods generally accepted by thepetroleum industry, and the reserves definitions and standards required by theUnited States SEC. Generally accepted methods for estimating reserves includevolumetric calculations, material balance techniques, production and pressuredecline curve analysis, analogy with similar reservoirs, and reservoirsimulation. The

 

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methodor combination of methods used is based on our professional judgment andexperience.

 

Discovered oil and natural gas reserves are generally produced onlywhen they are economically recoverable. As such, oil and gas prices and capitaland operating costs have an impact on whether reserves will ultimately beproduced. As required by United States SEC rules, reserves represent thequantities that are expected to be economically recoverable using existingprices and costs. Estimates may change substantially as additional data fromongoing development activities and production performance becomes available andas economic conditions impacting oil and gas prices and costs change.

 

Generally, operations are subject to various levels of governmentcontrols and regulations. These laws and regulations may include mattersrelating to land tenure, drilling, production practices, environmentalprotection, marketing and pricing policies, royalties, various taxes and leviesincluding income tax, and foreign trade and investment that are subject tochange from time to time. Current legislation is generally a matter of publicrecord, and additional legislation or amendments that will affect reserves orwhen any such proposals, if enacted, might become effective generally cannot bepredicted. Changes in government regulations could affect reserves or relatedeconomics. In the regions that are currently being evaluated, we believe wehave applied existing regulations appropriately.

 

Certain properties in which Nexen has an interest are subject to theterms of various profit sharing or joint operating agreements. The terms ofthese agreements generally allow for working interest participants to bereimbursed for portions of capital costs and operating expenses and to share inthe profits. The reimbursements and profit proceeds are converted to a barrelof oil equivalent or standard cubic foot of gas equivalent by dividing byproduct prices to determine the “entitlement reserves.” These entitlementreserves are equivalent in principle to net reserves and are used to calculatean equivalent net share, termed an “entitlement interest.” In this report,Nexen reserves or interest for certain properties subject to these agreementsis the entitlement based on Nexen’s working interest.

 

**Nexen Estimates**

 

Nexen has represented that its estimated proved and probable reservesattributable to the evaluated properties are based on United States SECdefinitions. It represents that its estimates of the reserves attributable tothese properties represent less than 5 percent of

 

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itstotal company proved reserves and less than 5 percent of its total companyprobable reserves on an equivalent barrel basis. Due to disclosure restrictionsrequired by the Nigerian Government, Nexen’s estimates are not presentedherein.

 

**Reserves Audit Opinion**

 

DeGolyer and MacNaughton has used all procedures and methods that itconsiders necessary to prepare this report.

 

In our opinion, the information relating to estimated net proved andnet probable reserves of oil, condensate, natural gas liquids, and gascontained in this report has been prepared according to the definitions anddisclosure guidelines required by the United States SEC within Paragraphs932-235-50-4, 932-235-50-6, 932-235-50-7, and 932-235-50-9 of the AccountingStandards Update 932-235-50, Extractive Industries — Oil and Gas (Topic 932):Oil and Gas Reserve Estimation and Disclosures (January 2010) of theFinancial Accounting Standards Board and Rules 4—10(a) (1)—(32) ofRegulation S—X and Rules 302(b), 1201, and 1202(a) (1), (2), (3),(4), (5), (8) of Regulation S—K of the United States Securities andExchange Commission.

 

In comparing the detailed proved and proved-plus-probable reservesestimates prepared by us to those prepared by Nexen, we have found differences,both positive and negative. In our opinion, the proved and proved-plus-probablereserves for the reviewed properties as estimated by Nexen are, in aggregatewhen compared to our estimates on the basis of equivalent barrels, reasonablewithin the established audit tolerance guidelines as set forth in the StandardsPertaining to the Estimating and Auditing of Oil and Gas Reserves Informationpromulgated by the Society of Petroleum Engineers.

 

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DeGolyer and MacNaughton is an independent petroleum engineeringconsulting firm that has been providing petroleum consulting servicesthroughout the world for over 70 years. DeGolyer and MacNaughton does not haveany financial interest, including stock ownership, in Nexen. Our fees were notcontingent on the results of our evaluation. This letter report has beenprepared at the request of Nexen and should not be used for purposes other thanthose for which it is intended.

 

 
|   |                           | Submitted,                               |
|--------|--------------------------------|------------------------------------------|
|   |                           |                                     |
|   |                           | /s/  DeGolyer and MacNaughton            |
|   |                           |                                     |
|   |                           | DeGOLYER  and MacNAUGHTON                |
|   |                           | Texas  Registered Engineering Firm F-716 |
|   |                           |                                     |
|   |                           |                                     |
| cc:    | Mr. Craig  Beattie        |                                     |   |
|   | V.P. Technical Assurance       |                                     |   |
|   | Nexen International Division   |                                     |   |
|   | Mr. Brad  Kopas           |                                     |   |
|   | Deloitte & Touche LLP |                                     |   |
|   |                           |                                     |   |
|   |                           |                                     |   |
|   |                           | /s/  Lloyd W. Cade, P.E.                 |
| [SEAL] |                           |                                     |
|   |                           |                                     | Lloyd  W. Cade, P.E. |
|   |                           |                                     | Senior  Vice President |
|   |                           |                                     | DeGolyer  and MacNaughton |
|        |                                |                                          |  |  |

 

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