**Endeavour International Corporation**                       Net Reserves Future Net Revenue ($)  Oil NGL Gas     Present WorthCountry/Category (Barrels) (Barrels) (MCF) Total at 10%UNITED KINGDOM                                         Proved Developed Producing  1,055,465   26,559   497,832   42,386,138   42,264,733 Proved Developed Non-Producing  152,411   5,633   57,333   9,354,294   8,111,145 Proved Undeveloped  2,423,845   0   55,621,793   252,783,202   150,444,221                      Total Proved  3,631,722   32,193   56,176,957   304,523,633   200,820,098                      UNITED STATES                                         Proved Developed Producing  14,201   0   13,145,879   40,247,126   28,174,878 Proved Developed Non-Producing  179   0   135,431   259,404   64,602 Proved Undeveloped  44,412   0   18,495,233   28,957,851   9,507,042                      Total Proved  58,792   0   31,776,543   69,464,380   37,746,522                      ALL PROPERTIES                                         Proved Developed Producing  1,069,666   26,559   13,643,711   82,633,264   70,439,611 Proved Developed Non-Producing  152,590   5,633   192,764   9,613,697   8,175,747 Proved Undeveloped  2,468,257   0   74,117,025   281,741,053   159,951,262                      Total Proved  3,690,514   32,193   87,953,500   373,988,014   238,566,620 *Totals may not add because of rounding.*The oil reserves shown include crude oil and condensate. Oil and natural gas liquids (NGL) volumesare expressed in barrels that are equivalent to 42 United States gallons. Gas volumes areexpressed in thousands of cubic feet (MCF) at standard temperature and pressure bases. Monetaryvalues shown in this report are expressed in United States dollars ($).When compared on a field-by-field basis, some of the estimates of Endeavour are greater and someare less than the estimates of Netherland, Sewell & Associates, Inc. (NSAI). However, in ouropinion the estimates of Endeavour’s proved reserves and future revenue shown herein are, in theaggregate, reasonable and have been prepared in accordance with the Standards Pertaining to theEstimating and Auditing of Oil and Gas Reserves Information promulgated by the Society of PetroleumEngineers (SPE
 

 
**Endeavour International Corporation**Standards). Additionally, these estimates, in the aggregate, are within therecommended 10 percent tolerance threshold set forth in the SPEStandards. We are satisfied withthe methods and procedures used by Endeavour in preparing the December 31, 2010, estimates ofreserves and future revenue, and we saw nothing of an unusual nature that would cause us to takeexception with the estimates, in the aggregate, as prepared by Endeavour.The estimates shown herein are for proved reserves. Endeavour’s estimates do not include probableand possible reserves that exist for these properties, nor do they include any value forundeveloped acreage beyond those tracts for which undeveloped reserves have been estimated.Reserves categorization conveys the relative degree of certainty; reserves subcategorization isbased on development and production status. The estimates of reserves and future revenue includedherein have not been adjusted for risk.Oil and NGL prices used by Endeavour are based on the 12-month unweighted arithmetic average of thefirst-day-of-the-month price for each month in the period January through December 2010. ForUnited Kingdom properties, the average Dated Brent price of $79.37 per barrel is adjusted by fieldfor quality, transportation fees, and regional price differentials. For United States properties,the average West Texas Intermediate price of $75.96 per barrel is adjusted by field for quality,transportation fees, and regional price differentials. All oil and NGL prices are held constantthroughout the lives of the properties. The average adjusted product prices weighted by productionover the remaining lives of the properties are $78.89 per barrel of oil and $41.70 per barrel ofNGL.Gas prices used by Endeavour are based on the 12-month unweighted arithmetic average of thefirst-day-of-the-month price for each month in the period January through December 2010. ForUnited Kingdom properties, the average National Balancing Point spot price of 42.49 pence per therm(equivalent to $6.591 per MMBTU) is adjusted by field for energy content, transportation fees, andregional price differentials. For United States properties, the average Henry Hub spot price of$4.376 per MMBTU is adjusted by field for energy content, transportation fees, and regional pricedifferentials. All gas prices are held constant throughout the lives of the properties. Theaverage adjusted gas price weighted by production over the remaining lives of the properties is$6.142 per MCF.Lease and well operating costs used by Endeavour are based on historical operating expense records.These costs include the per-well overhead expenses allowed under joint operating agreements alongwith estimates of costs to be incurred at and below the district and field levels. Headquartersgeneral and administrative overhead expenses of Endeavour are included to the extent that they arecovered under joint operating agreements for the operated properties. Lease and well operatingcosts are held constant throughout the lives of the properties. Endeavour’s estimates of capitalcosts are included as required for
 

 
**Endeavour International Corporation**workovers, new development wells, production equipment, andabandonment. The future capital costs are held constant to the date of expenditure.The reserves shown in this report are estimates only and should not be construed as exactquantities. Proved reserves are those quantities of oil and gas which, by analysis of engineeringand geoscience data, can be estimated with reasonable certainty to be economically producible.Estimates of reserves may increase or decrease as a result of market conditions, future operations,changes in regulations, or actual reservoir performance. In addition to the primary economicassumptions discussed herein, estimates of Endeavour and NSAI are based on certain assumptionsincluding, but not limited to, that the properties will be developed consistent with currentdevelopment plans, that the properties will be operated in a prudent manner, that no governmentalregulations or controls will be put in place that would impact the ability of Endeavour to recoverthe reserves, and that projections of future production will prove consistent with actualperformance. If the reserves are recovered, the revenues therefrom and the costs related theretocould be more or less than the estimated amounts. Because of governmental policies anduncertainties of supply and demand, the sales rates, prices received for the reserves, and costsincurred in recovering such reserves may vary from assumptions made while preparing theseestimates.It should be understood that our audit does not constitute a complete reserves study of the auditedoil and gas properties. Our audit consisted primarily of substantive testing, wherein we conducteda detailed review of all properties. In the conduct of our audit, we have not independentlyverified the accuracy and completeness of information and data furnished by Endeavour with respectto ownership interests, oil and gas production, well test data, historical costs of operation anddevelopment, product prices, or any agreements relating to current and future operations of theproperties and sales of production. However, if in the course of our examination something came toour attention that brought into question the validity or sufficiency of any such information ordata, we did not rely on such information or data until we had satisfactorily resolved ourquestions relating thereto or had independently verified such information or data. Our audit didnot include a review of Endeavour’s overall reserves management processes and practices.We used standard engineering and geoscience methods, or a combination of methods, includingperformance analysis, volumetric analysis, analogy, and reservoir modeling, that we considered tobe appropriate and necessary to establish the conclusions set forth herein. As in all aspects ofoil and gasevaluation, there are uncertainties inherent in the interpretation of engineering and geosciencedata; therefore, our conclusions necessarily represent only informed professional judgment.Supporting data documenting this audit, along with data provided by Endeavour, are on file in ouroffice. The technical persons responsible for conducting this audit meet the requirementsregarding qualifications, independence, objectivity, and confidentiality set forth in the SPEStandards. We are
 

 
**Endeavour International Corporation**independent petroleum engineers, geologists, geophysicists, and petrophysicists;we do not own an interest in these properties nor are we employed on a contingent basis.                 Sincerely,                   **NETHERLAND, SEWELL & ASSOCIATES, INC.**                   Texas Registered Engineering Firm F-002699                   By: /s/ C.H. (Scott) Rees III C.H. (Scott) Rees III, P.E.          Chairman and Chief Executive Officer             By: /s/ Derek F. Newton Derek F. Newton, P.E. 97689   By: /s/ David E. Nice David E. Nice, P.G. 346    Vice President     Vice President             Date Signed: February 28, 2011   Date Signed: February 28, 2011  DFN:KEA
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