<PAGE>
 
 
                         [NSA LETTERHEAD APPEARS HERE]
 
                                                                   EXHIBIT 99.8

                                 March 21, 1997
 
Mr. Ron E. Hooper
Burlington Resources Coal Seam Gas Royalty Trust
NationsBank of Texas, N.A., Trustee
NationsBank Plaza
901 Main Street, 17th Floor
Dallas, Texas 75202
 
Dear Mr. Hooper:
 
  In accordance with your request, we have estimated, as of January 1, 1997,
the Section 29 nonconventional fuels federal income tax credit attributable to
the Burlington Resources Coal Seam Gas Royalty Trust (Trust) net profits
interest in the Fruitland Coal Formation underlying the Northeast Blanco Unit,
Rio Arriba and San Juan Counties, New Mexico, as listed in the accompanying
tabulations. The tax credit is derived from the Burlington Resources Oil & Gas,
Inc. (Burlington) interest in the proved gas reserves as estimated in our report
dated March 20, 1997. This report has been prepared using constant prices and
costs and conforms to the guidelines of the Securities and Exchange Commission
(SEC).
 
  The estimated net proved reserves in this report are defined as the portion
of the gross reserves attributable to the Trust net profits interest. These
reserves were reduced by the amount of gas reserves necessary to cover the
lease operating costs at the current gas price. As presented in the
accompanying summary projection, Table I, we estimate the Trust net reserves
and the tax credit attributable to the Trust net profits interest, as of
January 1, 1997, to be:
 
<TABLE>
<CAPTION>
                   TRUST NET RESERVES       FUTURE TAX CREDIT
                  --------------------- -------------------------
                  CONDENSATE    GAS                 PRESENT WORTH
    CATEGORY      (BARRELS)    (MCF)       TOTAL       AT 10%
----------------  ---------- ---------- ----------- -------------
<S>               <C>        <C>        <C>         <C>
Proved Developed      0      38,197,677  $36,055,600 $28,479,900
</TABLE>
 
  Gas volumes are expressed in thousands of standard cubic feet (MCF) at the
contract temperature and pressure bases. These properties no longer produce
commercial volumes of condensate.
 
  This report includes a summary projection of reserves and future tax credit
along with one-line summaries of reserves, economics, and basic data by lease.
For the purposes of this report, the term "lease" refers to a single economic
projection.
 
  The estimated reserves and future tax credit shown in this report are for
proved developed reserves only. Our study indicates that there are no proved
undeveloped reserves for these properties at this time. In accordance with SEC
guidelines, our estimates do not include any value for probable or possible
reserves which may exist for these properties. This report does not include any
value which could be attributed to interests in undeveloped acreage.
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  For the purposes of this report, a field inspection of the properties has not
been performed nor has the mechanical operation or condition of the wells and
their related facilities been examined. We have not investigated possible
environmental liability related to the properties; therefore, our estimates do
not include any costs which may be incurred due to such possible liability.
Also, our estimates do not include any salvage value for the lease and well
equipment nor the cost of abandoning the properties.
 
  An estimated 1996 tax credit of $1.05 per MMBTU is held constant in
accordance with SEC guidelines.
 
  Lease and well operating costs are based on operating expense records
provided by Burlington. These costs include the per-well overhead expenses
allowed under joint operating agreements along with costs estimated to be
incurred at and below the district and field levels. General and administrative
overhead expenses of the Trustee are not included. Lease and well operating
costs are held constant in accordance with SEC guidelines.  Capital costs are 
included as required for workovers and production equipment.
 
  We have made no investigation of potential gas volume and value imbalances
which may have resulted from overdelivery or underdelivery to the Burlington
interest. Therefore, our estimates of reserves and tax credit do not include
adjustments for the settlement of any such imbalances; our projections are
based on Burlington receiving its net revenue interest share of estimated future
gross gas production.
 
  The reserves included in this report are estimates only and should not be
construed as exact quantities. They may or may not be recovered; if recovered,
the tax credit therefrom and the costs related thereto could be more or less
than the estimated amounts. The sales rates, prices received for the reserves,
and costs incurred in recovering such reserves may vary from assumptions
included in this report due to governmental policies and uncertainties of
supply and demand. Also, estimates of reserves may increase or decrease as a
result of future operations.
 
  In evaluating the information at our disposal concerning this report, we have
excluded from our consideration all matters as to which legal or accounting,
rather than engineering and geological, interpretation may be controlling. As
in all aspects of oil and gas evaluation, there are uncertainties inherent in
the interpretation of engineering and geological data; therefore, our
conclusions necessarily represent only informed professional judgments.
 
  The titles to the properties have not been examined by Netherland, Sewell &
Associates, Inc., nor has the actual degree or type of interest owned been
independently confirmed. The data used in our estimates were obtained from
Burlington Resources Oil & Gas, Inc. and the nonconfidential files of
Netherland, Sewell & Associates, Inc. and were accepted as accurate. We are
independent petroleum engineers, geologists and geophysicists; we do not own an
interest in these properties and are not employed on a contingent basis. Basic
geologic and field performance data together with our engineering work sheets
are maintained on file in our office.
 
                                                  Very truly yours,
 
                                                  /s/ Frederic D. Sewell