Exhibit 99.1
 
  
 Re:
    
    Encore Acquisition CompanyReserves and Future Net RevenuesAs of December 31, 2009SEC Case
    Reserves and Future Net Revenues as of December 31, 2009
 Net Reserves
    
    Future Net RevenuesDiscounted at10% PerOil,
    
    Gas,
    
    Undiscounted,
    
    Year,Reserves Category
    
    MBbls.
    
    MMcf
    
    M$
    
    M$Proved Producing
    
    
    118,887
    
    
    
    312,179
    
    
    
    4,052,469
    
    
    
    2,010,840Proved Nonproducing
    
    
    2,514
    
    
    
    10,243
    
    
    
    125,523
    
    
    
    38,167Proved Undeveloped
    
    
    25,693
    
    
    
    116,650
    
    
    
    811,185
    
    
    
    189,240EAC Corporate Indirect Costs
    
    
    
    
    
    
    
    
    
    
    -178,046
    
    
    
    -97,210Total Proved
    
    
    147,094
    
    
    
    439,072
    
    
    
    4,811,131
    
    
    
    2,141,037
 Two Houston Center  909 Fannin Street , Suite 1300  Houston , Texas 77010  telephone 713-651-9455  TELEFAX 713-654-9914  e-mail: mail@millerandients.com




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Encore Acquisition Company
    
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Encore Acquisition Company
    
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Encore Acquisition Company
    
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Encore Acquisition Company
    
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Encore Acquisition Company
    
    January 20, 2010Page 6
  Very truly yours,MILLER AND LENTS, LTD.Texas Registered
Engineering Firm No. F-1442By /s/ Leslie A. Fallon

Leslie A. Fallon, P.E.
    
    (SEAL)Vice PresidentBy /s/ Michael S. Young

Michael S. Young
    
    (SEAL)Senior Vice PresidentBy /s/ Carl D. Richard

Carl D. Richard, P. E.
    
    (SEAL)Senior Vice President




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Appendix
Page 1 of 3
 Reserves Definitions In Accordance With  Securities and Exchange Commission Regulation S-X
 Reserves
   Proved Oil and Gas Reserves
  1.
    
    The area of the reservoir considered as proved includes:
 a.
    
    The area
identified by drilling and limited by fluid contacts, if any, andb.
    
    Adjacent undrilled portions of the reservoir that can, with reasonable certainty, be judged
to be continuous with it and to contain economically producible oil or gas on the basis of
available geoscience and engineering data.
 2.
    
    In the absence of data on fluid contacts, proved quantities in a reservoir
are limited by the lowest known hydrocarbons (LKH) as seen in a well penetration
unless geoscience, engineering, or performance data and reliable technology
establishes a lower contact with reasonable certainty.3.
    
    Where direct observation from well penetrations has defined a highest known
oil (HKO) elevation and the potential exists for an associated gas cap, proved oil
reserves may be assigned in the structurally higher portions of the reservoir only if
geoscience, engineering, or performance data and reliable technology establish the
higher contact with reasonable certainty.4.
    
    Reserves which can be produced economically through application of improved
recovery techniques (including, but not limited to, fluid injection) are included in
the proved classification when:
 a.
    
    Successful testing by a pilot project in an area of the reservoir with properties no more
favorable than in the reservoir as a whole, the operation of an installed program in the reservoir
or an analogous reservoir, or other evidence using reliable technology establishes the reasonable
certainty of the engineering analysis on which the project or program was based; andb.
    
    The project has been approved for development by all necessary parties and entities,
including governmental entities.
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Appendix
Page 2 of 3
 5.
    
    Existing economic conditions include prices and costs at which economic
producibility from a reservoir is to be determined. The price shall be the average
price during the 12-month period prior to the ending date of the period covered by the
report, determined as an unweighted arithmetic average of the first-day-of-the-month
price for each month within such period, unless prices are defined by contractual
arrangements, excluding escalations based upon future conditions.
 Developed Oil and Gas Reserves
  1.
    
    Through existing wells with existing equipment and operating methods or in
which the cost of the required equipment is relatively minor compared to the cost of a
new well; and2.
    
    Through installed extraction equipment and infrastructure operational at the
time of the reserves estimate if the extraction is by means not involving a well.
 Undeveloped Oil and Gas Reserves
  1.
    
    Reserves on undrilled acreage shall be limited to those directly offsetting
development spacing areas that are reasonably certain of production when drilled,
unless evidence using reliable technology exists that establishes reasonable certainty
of economic producibility at greater distances.2.
    
    Undrilled locations can be classified as having undeveloped reserves only if
a development plan has been adopted indicating that they are scheduled to be drilled
within five years, unless the specific circumstances, justify a longer time.3.
    
    Under no circumstances shall estimates for undeveloped reserves be
attributable to any acreage for which an application of fluid injection or other
improved recovery technique is contemplated, unless such techniques have been proved
effective by actual projects in the same reservoir or an analogous reservoir, as
defined below, or by other evidence using reliable technology establishing reasonable
certainty.Analogous Reservoir
  1.
    
    Same geological formation (but not necessarily in
pressure communication with the reservoir of interest);2.
    
    Same environment of deposition;3.
    
    Similar geological structure; and4.
    
    Same drive mechanism.
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Appendix
Page 3 of 3
 Probable Reserves
  1.
    
    When deterministic methods are used, it is as likely as not that actual
remaining quantities recovered will exceed the sum of estimated proved plus probable
reserves. When probabilistic methods are used, there should be at least a 50%
probability that the actual quantities recovered will equal or exceed the proved plus
probable reserves estimates.2.
    
    Probable reserves may be assigned to areas of a reservoir adjacent to proved
reserves where data control or interpretations of available data are less certain,
even if the interpreted reservoir continuity of structure or productivity does not
meet the reasonable certainty criterion. Probable reserves may be assigned to areas
that are structurally higher than the proved area if these areas are in communication
with the proved reservoir.3.
    
    Probable reserves estimates also include potential incremental quantities
associated with a greater percentage recovery of the hydrocarbons in place than
assumed for proved reserves.4.
    
    See also guidelines in Items 4 and 6 under Possible Reserves.
 Possible Reserves
  1.
    
    When deterministic methods are used, the total quantities ultimately
recovered from a project have a low probability of exceeding proved plus probable plus
possible reserves. When probabilistic methods are used, there should be at least a 10%
probability that the total quantities ultimately recovered will equal or exceed the
proved plus probable plus possible reserves estimates.2.
    
    Possible reserves may be assigned to areas of a reservoir adjacent to
probable reserves where data control and interpretations of available data are
progressively less certain. Frequently, this will be in areas where geoscience and
engineering data are unable to define clearly the area and vertical limits of
commercial production from the reservoir by a defined project.3.
    
    Possible reserves also include incremental quantities associated with a
greater percentage recovery of the hydrocarbons in place than the recovery quantities
assumed for probable reserves.4.
    
    The proved plus probable and proved plus probable plus possible reserves
estimates must be based on reasonable alternative technical and commercial
interpretations within the reservoir or subject project that are clearly documented,
including comparisons to results in successful similar projects.5.
    
    Possible reserves may be assigned where geoscience and engineering data
identify directly adjacent portions of a reservoir within the same accumulation that
may be separated from proved areas by faults with displacement less than formation
thickness or other geological discontinuities and that have not been penetrated by a
wellbore, and the registrant believes that such adjacent portions are in communication
with the known (proved) reservoir. Possible reserves may be assigned to areas that are
structurally higher or lower than the proved area if these areas are in communication
with the proved reservoir.6.
    
    Pursuant to Item 3 under Proved Oil and Gas Reserves, where direct
observation has defined a highest known oil (HKO) elevation and the potential exists
for an associated gas cap, proved oil reserves should be assigned in the structurally
higher portions of the reservoir above the HKO only if the higher contact can be
established with reasonable certainty through reliable technology. Portions of the
reservoir that do not meet this reasonable certainty criterion may be assigned as
probable and possible oil or gas based on reservoir fluid properties and pressure
gradient interpretations.
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