Exhibit
99.1  WILLIAMSON PETROLEUM CONSULTANTS, INC. TEXAS
REGISTERED ENGINEERING FIRM F-81 303 VETERANS AIRPARK LANE, SUITE 1100 MIDLAND, TEXAS 79705 PHONE: 432-685-6100 FAX: 432-685-3909 E-MAIL: WPC@WPC-INC.COM  March
2, 2010  Warren
Resources, Inc. 34thFloor 1114
Avenue of the Americas New
York, New York  10036  Attention
Mr. Norman F. Swanton  Gentlemen:  Subject:
  Evaluation
  of Oil and Gas Reservesto
  the Interests ofWarren
  Resources, Inc.Effective
  December 31, 2009for
  Disclosure to theSecurities
  and Exchange CommissionWilliamson
  Project 9.9370  Williamson
Petroleum Consultants, Inc. performed the subject engineering evaluation
effective December 31, 2009 at your request for the purpose of an annual update
of the subject properties and to be used in Securities and Exchange Commission
(SEC) filings. This evaluation was completed February 4, 2010. The properties
evaluated represent 100 percent of the value of oil and gas interests owned by
Warren and are located in the states of California, New Mexico, North Dakota,
Texas, and Wyoming with the majority of the value in California.  Proved
reserves and future net revenue from oil and gas properties were evaluated in
accordance with the Definitions of Oil and Gas Reserves from 17 CFR § 210.4-10.
Following is a summary of the results of the proved evaluation effective December
31, 2009:  PROVEDDEVELOPEDPRODUCING
  
  PROVEDDEVELOPEDNONPRODUCING
  
  PROVEDUNDEVELOPED
  
  TOTALPROVEDNet Reserves to theEvaluated Interests:Oil/Condensate, MBBL
  
  7,932.725
  
  0.000
  
  2,288.620
  
  10,221.346Gas, MMCF
  
  49,867.797
  
  0.000
  
  13,031.740
  
  62,899.535Future Net Revenue, M$:Undiscounted
  
  303,827.656
  
  0.000
  
  106,595.242
  
  410,422.906Discounted Per Annumat 10.00 Percent
  
  191,449.484
  
  0.000
  
  49,842.488
  
  241,292.016  Note: Due to the method of rounding, Total Proved may not equal PDP +
PDNP + PU.


No study was
made to determine the existence of oil and gas reserves that would be
categorized as probable or possible. Oil reserves are expressed in thousands of
United States (U.S.) barrels (MBBL) of 42 U.S. gallons. Gas volumes are
expressed in millions of cubic feet (MMCF) at 60 degrees Fahrenheit and at the
legal pressure base that prevails in the state in which the reserves are
located. No adjustment of the individual gas volumes to a common pressure base
has been made.  Net income to
the evaluated interests is the future net revenue after consideration of
royalty revenue payable to others, taxes, operating expenses, investments,
salvage values, abandonment costs, and net profit interests, as applicable. The
future net revenue is before federal income tax and excludes consideration of
any encumbrances against the properties if such exist. No estimate of fair
market value was made.  All data
utilized in the preparation of this report with respect to interests,
reversionary status, oil and gas prices, gas contract terms, operating
expenses, investments, salvage values, abandonment costs, net profit interests,
well information, and current operating conditions, as applicable, were
provided by Warren. Production data were obtained from both public records and
the client. The dates of first production for nonproducing properties were
based on estimates by Warren and the actual dates may vary from those
estimated.  Average
first of the month index prices for January through December 2009 were used in
this evaluation as follows:  PRODUCT
  
  INDEX
  PRICE
  
  $/BBL or$/MMBTU
  
  PROPERTIESOil
  
  WTI
  Cash price
  
  61.18
  
  AllGas
  
  Henry
  Hub Cash price
  
  3.833
  
  Excludes
  WyomingGas
  
  Colorado
  Interstate Cash price
  
  3.035
  
  Wyoming  Oil
and gas differentials were calculated using wellhead prices provided by Warren.  All
capital and operating costs were provided by Warren. Operating expenses were
provided for a minimum of ten months ending no earlier than August 2009 for all
properties. All available data for each property were used to determine average
recurring expenses which are billable to the working interest owners. Expenses
for workovers, well stimulations, and other maintenance were not included in
the operating expenses unless such work was expected on a recurring basis.
Judgments for the exclusion of the nonrecurring expenses were made by Warren.
For new and developing properties where data were unavailable, operating
expenses were estimated by Warren based on analogy with similar properties. For
California properties, Warren provided operating cost models which separated
expenses between fixed costs, well costs, and fluid production costs.  2


State
production taxes have been deducted at the published rates as appropriate.   Average county ad valorem taxes were
deducted for those properties located in states for which the data were available
or calculated based on data provided by Warren.  Williamson
used all engineering and geological evaluation methods and procedures
considered necessary to prepare this evaluation. The estimates of reserves
contained in this report were determined by accepted industry methods. Methods
utilized in this report include extrapolation of historical production trends,
analogy to similar properties, and volumetric calculations. Where sufficient
production history and other data were available, reserves for producing
properties were determined by extrapolation of historical production trends.
Analogy to similar properties or volumetric calculations were used for
nonproducing properties and those producing properties which lacked sufficient
production history and other data to yield a definitive estimate of reserves.
Reserves projections based on analogy are subject to change due to subsequent
changes in the analogous properties or subsequent production from the evaluated
properties. Volumetric calculations are often based upon limited log and/or
core analysis data and incomplete reservoir fluid and formation rock data.
Since these limited data must frequently be extrapolated over an assumed
drainage area, subsequent production performance trends or material balance
calculations may cause the need for significant revisions to the estimates of
reserves.  The reserves
projections in this evaluation are based on the use of the available data and
accepted industry engineering methods. Future changes in any operational or
economic parameters or production characteristics of the evaluated properties
could increase or decrease their reserves. Unforeseen changes in market demand
or allowables set by various regulatory agencies could also cause actual
production rates to vary from those projected. It should be emphasized that
with the current economic uncertainties, fluctuation in market conditions could
significantly change the economics of the properties included in this report.  All
data have been reviewed for reasonableness and, unless obvious errors were
detected, have been accepted as correct. It should be emphasized that revisions
to the projections of reserves and economics included in this report may be
required if the provided data are revised for any reason. No inspection of the
properties was made as this was not considered within the scope of this
evaluation. No investigation was made of any environmental liabilities that
might apply to the evaluated properties, and no costs are included for any
possible related expenses.  Warren did
not request Williamson to assess the risks associated with regulatory issues
for the properties evaluated.Neither
salvage values nor abandonment costs were included in this evaluation.  Williamson
reserves the right to alter any of the reserves projections and the associated
economics included in this evaluation in any future evaluations based on
additional data that may be acquired.  3


Williamson
is an independent consulting firm and does not own any interests in the oil and
gas properties covered by this report. No employee, officer, or director of
Williamson is an employee, officer, or director of Warren. Neither the
employment of nor the compensation received by Williamson is contingent upon
the values assigned to the properties covered by this report.  Yours
very truly,  WILLIAMSON
PETROLEUM CONSULTANTS, INC.   /s/
  Roy C. WilliamsonRoy
  C. Williamson, Jr., P.E.  RCW/JDS/RCH/thb  AttachmentsWilliamson Petroleum Consultants, Inc.F-81  4