<PAGE>
 
 
                         [NSA LETTERHEAD APPEARS HERE]
 
                                                                   EXHIBIT 99.7

                                 March 20, 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, (1)
the future net revenue to the Burlington Resources Coal Seam Gas Royalty Trust
(Trust) net profits interest and (2) the proved reserves to the Burlington
Resources Coal Seam Gas Royalty Trust (Burlington) 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 Trust net
profits interest is derived from the Burlington interest in such proved
reserves. 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 Burlington interest to which the net
profits interest is applied. As presented in the accompanying summary
projection, Table I, we estimate the Burlington net reserves and the future net
revenue to the Trust net profits interest, as of January 1, 1997, to be:
 
<TABLE>
<CAPTION>
                BURLINGTON NET RESERVES  TRUST FUTURE NET REVENUE
                -----------------------  -------------------------
                  CONDENSATE    GAS                 PRESENT WORTH
    CATEGORY      (BARRELS)    (MCF)       TOTAL       AT 10%
----------------  ---------- ---------- ----------- -------------
<S>               <C>        <C>        <C>          <C>
Proved Developed      0      80,189,707 $116,306,100 $67,304,900
</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 revenue 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 revenue 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.
 
  Future gross revenue in this report is to the Burlington interest prior to
deducting state production taxes and ad valorem taxes. Future net revenue is the
95 percent net profits interest to the Trust after deducting the Burlington
working interest share of these taxes and operating expenses, but before
consideration of federal income taxes. Our estimates of future net revenue have
not been adjusted to account for the Section 29 nonconventional fuels federal
income tax credit. In accordance with
<PAGE>
 
SEC guidelines, the future net revenue has been discounted at an annual rate of
10 percent to determine its "present worth." The present worth is shown to
indicate the effect of time on the value of money and should not be construed
as being the fair market value of the Trust net profits interests.
 
  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.
 
  The gas price used in this report is based on the December 1996 net price
received; adjusted for BTU content, gathering fee, and shrinkage.  The price is 
also adjusted as specified in the gas purchase contract under provisions 
related to the sharing price and price credit account and 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 future revenue 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 revenues 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