<PAGE>

                                                                    EXHIBIT 99.1


March 27, 1998



Edge Petroleum Corporation
2100 Texaco Heritage Plaza
Houston, Texas  77002

Gentlemen:


          At your request, we have prepared an estimate of the reserves, future
production, and income attributable to certain leasehold and royalty interests
of Edge Petroleum Corporation (Edge) as of December 31, 1997.  The subject
properties are located in the states of Alabama, Louisiana, Mississippi, and
Texas.  The income data were estimated using the Securities and Exchange
Commission (SEC) guidelines for future price and cost parameters.

          The estimated reserves and future income amounts presented in this
report are related to hydrocarbon prices.  December 1997 hydrocarbon prices were
used in the preparation of this report as required by SEC guidelines; however,
actual future prices may vary significantly from December 1997 prices.
Therefore, volumes of reserves actually recovered and amounts of income actually
received may differ significantly from the estimated quantities presented in
this report.  The results of this study are summarized below.



                                 SEC PARAMETERS
                     Estimated Net Reserves and Income Data
                   Certain Leasehold and Royalty Interests of
                           EDGE PETROLEUM CORPORATION
                            As of December 31, 1997
               -------------------------------------------------

<TABLE>
<CAPTION>
                                                                                      Proved
                                               -------------------------------------------------------------------------------
                                                             Developed
                                              --------------------------------------                                  Total
                                                  Producing           Non-Producing           Undeveloped             Proved
                                              ----------------     ------------------    -----------------     ----------------
<S>                                            <C>                  <C>                   <C>                   <C>
NET REMAINING RESERVES
----------------------
  Oil/Condensate - Barrels                        331,374                    185,577               220,177              737,128
  Plant Products - Barrels                         70,797                     58,261                     0              129,058
  Gas - MMCF                                        8,377                      9,489                11,257               29,123

INCOME DATA
-----------
  Future Gross Revenue                        $24,541,573                $24,124,209           $28,955,851          $77,621,633
  Deductions                                    4,877,720                  3,841,482             7,633,774           16,352,976
                                               ----------                 ----------            ----------           ----------
  Future Net Income (FNI)                     $19,663,853                $20,282,727           $21,322,077          $61,268,657

  Discounted FNI @ 10%                        $16,756,263                $11,089,209           $13,043,156          $40,888,628


</TABLE>
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Edge Petroleum Corporation
March 27, 1998


     Liquid hydrocarbons are expressed in standard 42 gallon barrels.  All gas
volumes are sales gas expressed in millions of cubic feet (MMCF) at the official
temperature and pressure bases of the areas in which the gas reserves are
located.

     The future gross revenue is after the deduction of production taxes.  The
deductions are comprised of the normal direct costs of operating the wells, ad
valorem taxes, recompletion costs, and development costs.  The future net income
is before the deduction of state and federal income taxes and general
administrative overhead, and has not been adjusted for outstanding loans that
may exist nor does it include any adjustment for cash on hand or undistributed
income.  No attempt was made to quantify or otherwise account for any
accumulated gas production imbalances that may exist.  Gas reserves account for
approximately 84 percent and liquid hydrocarbon reserves account for the
remaining 16 percent of total future gross revenue from proved reserves.


RESERVES INCLUDED IN THIS REPORT
--------------------------------

     The proved reserves included herein conform to the definition as set forth
in the Securities and Exchange Commission's Regulation S-X Part 210.4-10 (a) as
clarified by subsequent Commission Staff Accounting Bulletins.  The definition
of proved reserves is included in the section entitled "Definitions of Reserves"
which is attached with this report.

     The proved developed non-producing reserves included herein are comprised
of shut-in and behind pipe categories.  The various reserve status categories
are defined in the section entitled "Reserve Status Categories (SEC)" which is
attached with this report.


ESTIMATES OF RESERVES

     In general, the reserves included herein were predominantly estimated
by the volumetric method due to the limited production history of the wells
considered in this study.  However, performance methods were used in certain
cases where characteristics of the data indicated such other methods were more
appropriate in our opinion.  The reserves estimated by the performance method
utilized extrapolations of various historical data in those cases where such
data were definitive.  Reserves were estimated by the volumetric method in those
cases where there were inadequate historical performance data to establish a
definitive trend or where the use of production performance data as a basis for
the reserve estimates was considered to be inappropriate.

     The reserves included in this report are estimates only and should not be
construed as being exact quantities.  They may or may not be actually recovered,
and if recovered, the revenues therefrom and the actual costs related thereto
could be more or less than the estimated amounts.  Moreover, estimates of
reserves may increase or decrease as a result of future operations.


Future Production Rates

     Initial production rates are based on the current producing rates for those
wells now on production.  Test data and other related information were used to
estimate the anticipated initial production rates for those wells or locations
which are not currently producing.  If no production decline trend has been
established, future production rates were held constant, or adjusted for the
effects of curtailment where appropriate, until a decline in ability to produce
was anticipated.  An estimated rate of decline was then applied to depletion of
the reserves.  If a decline trend has been established, this trend was used as
the basis for estimating future production rates.  For reserves not yet on
production, sales were estimated to commence at an anticipated date furnished by
Edge.

     In general, we estimate that future gas production rates limited by
allowables or marketing conditions will continue to be the same as the average
rate for the latest available 12 months of actual production until such time
that the well or wells are incapable of producing at this rate.  The well or
wells were then projected to decline at their decreasing delivery capacity rate.
Our general policy on estimates of future gas production rates is adjusted when
necessary to reflect actual gas market conditions in specific cases.

     The future production rates from wells now on production may be more or
less than estimated because of changes in market demand or allowables set by
regulatory bodies.  Wells or locations which are not currently producing may
start producing earlier or later than anticipated in our estimates of their
future production rates.
<PAGE>

Edge Petroleum Corporation
March 27, 1998


HYDROCARBON PRICES


     Edge furnished us with prices in effect at December 31, 1997 and these
prices were held constant except for known and determinable escalations.  In
accordance with Securities and Exchange Commission guidelines, changes in liquid
and gas prices subsequent to December 31, 1997 were not taken into account in
this report.  Future prices used in this report are discussed in more detail in
the section entitled "Hydrocarbon Pricing Parameters" which is attached with
this report.


COSTS

     Operating costs for the leases and wells in this report are based on the
operating expense reports of Edge and include only those costs directly
applicable to the leases or wells.  When applicable, the operating costs include
a portion of general and administrative costs allocated directly to the leases
and wells under terms of operating agreements.  No deduction was made for
indirect costs such as general administration and overhead expenses, loan
repayments, interest expenses, and exploration and development prepayments that
are not charged directly to the leases or wells.

     Development costs were furnished to us by Edge and are based on
authorizations for expenditure for the proposed work or actual costs for similar
projects. The estimated net cost of abandonment after salvage was included for
properties where abandonment costs net of salvage are significant. At the
request of Edge, their estimate of zero abandonment costs after salvage value
for onshore properties was used in this report. Ryder Scott has not performed a
detailed study of the abandonment costs nor the salvage value and makes no
warranty for Edge's estimate.

     Current costs were held constant throughout the life of the properties.


GENERAL

     While it may reasonably be anticipated that the future prices received for
the sale of production and the operating costs and other costs relating to such
production may also increase or decrease from existing levels, such changes
were, in accordance with rules adopted by the SEC, omitted from consideration in
making this evaluation.

     The estimates of reserves presented herein were based upon a detailed study
of the properties in which Edge owns an interest; however, we have not made any
field examination of the properties.  No consideration was given in this report
to potential environmental liabilities which may exist nor were any costs
included for potential liability to restore and clean up damages, if any, caused
by past operating practices.  Edge has informed us that they have furnished us
all of the accounts, records, geological and engineering data, and reports and
other data required for this investigation.  The ownership interests, prices,
and other factual data furnished by Edge were accepted without independent
verification.  The estimates presented in this report are based on data
available through November 1997.

     Neither we nor any of our employees have any interest in the subject
properties and neither the employment to make this study nor the compensation is
contingent on our estimates of reserves and future income for the subject
properties.

     This report was prepared for the exclusive use and sole benefit of Edge
Petroleum Corporation.  The data, work papers, and maps used in this report are
available for examination by authorized parties in our offices.  Please contact
us if we can be of further service.


                                                    Very truly yours,



                                                /S/ RYDER SCOTT COMPANY
                                                    PETROLEUM  ENGINEERS



                                                    Michael F. Stell, P.E.
                                                    Vice President
<PAGE>

DEFINITIONS OF RESERVES


PROVED RESERVES  (SEC DEFINITION)

          Proved reserves of crude oil, condensate, natural gas, and natural gas
liquids are estimated quantities that geological and engineering data
demonstrate with reasonable certainty to be recoverable in the future from known
reservoirs under existing operating conditions, i.e., prices and costs as of the
date the estimate is made.  Prices include consideration of changes in existing
prices provided only by contractual arrangements, but not on escalation based on
future conditions.

          Reservoirs are considered proved if economic producibility is
supported by either actual production or conclusive formation test.  In certain
instances, proved reserves are assigned on the basis of a combination of core
analysis and electrical and other type logs which indicate the reservoirs are
analogous to reservoirs in the same field which are producing or have
demonstrated the ability to produce on a formation test.  The area of a
reservoir considered proved includes (1) that portion delineated by drilling and
defined by fluid contacts, if any, and (2) the adjoining portions not yet
drilled that can be reasonably judged as economically productive on the basis of
available geological and engineering data.  In the absence of data on fluid
contacts, the lowest known structural occurrence of hydrocarbons controls the
lower proved limit of the reservoir.

          Reserves that can be produced economically through the application of
improved recovery techniques are included in the proved classification when
these qualifications are met:  (1) successful testing by a pilot project or the
operation of an installed program in the reservoir provides support for the
engineering analysis on which the project or program was based, and (2) it is
reasonably certain the project will proceed. Improved recovery includes all
methods for supplementing natural reservoir forces and energy, or otherwise
increasing ultimate recovery from a reservoir, including (1) pressure
maintenance, (2) cycling, and (3) secondary recovery in its original sense.
Improved recovery also includes the enhanced recovery methods of thermal,
chemical flooding, and the use of miscible and immiscible displacement fluids.

          Proved natural gas reserves are comprised of non-associated,
associated and dissolved gas.  An appropriate reduction in gas reserves has been
made for the expected removal of natural gas liquids, for lease and plant fuel,
and for the exclusion of non-hydrocarbon gases if they occur in significant
quantities and are removed prior to sale.  Estimates of proved reserves do not
include crude oil, natural gas, or natural gas liquids being held in underground
or surface storage.

          Proved reserves are estimates of hydrocarbons to be recovered from a
given date forward.  They may be revised as hydrocarbons are produced and
additional data become available.
<PAGE>

RESERVE STATUS CATEGORIES (SEC)


Reserve status categories define the development and producing status of wells
and/or reservoirs.


PROVED DEVELOPED

     Proved developed oil and gas reserves are reserves that can be expected to
be recovered through existing wells with existing equipment and operating
methods.  Additional oil and gas expected to be obtained through the application
of fluid injection or other improved recovery techniques for supplementing the
natural forces and mechanisms of primary recovery should be included as "proved
developed reserves" only after testing by a pilot project or after the operation
of an installed program has confirmed through production response that increased
recovery will be achieved.

     Developed reserves may be subcategorized as producing or non-producing
using the SPE/WPC definitions:


   Producing

   Reserves sub-categorized as producing are expected to be recovered from
   completion intervals which are open and producing at the time of the
   estimate.  Improved recovery reserves are considered producing only after the
   improved recovery project is in operation.

   Non-Producing

   Reserves sub-categorized as non-producing include shut-in and behind pipe
   reserves.  Shut-in reserves are expected to be recovered from (1) completion
   intervals which are open at the time of the estimate but which have not
   started producing, (2) wells which were shut-in for market conditions or
   pipeline connections, or (3) wells not capable of production for mechanical
   reasons.  Behind pipe reserves are expected to be recovered from zones in
   existing wells, which will require additional completion work or future
   recompletion prior to the start of production.


PROVED UNDEVELOPED

     Proved undeveloped oil and gas reserves are reserves that are expected to
be recovered from new wells on undrilled acreage, or from existing wells where a
relatively major expenditure is required for recompletion.  Reserves on
undrilled acreage shall be limited to those drilling units offsetting productive
units that are reasonably certain of production when drilled.  Proved reserves
for other undrilled units can be claimed only where it can be demonstrated with
reasonable certainty that there is continuity of production from the existing
productive formation.  Estimates for proved undeveloped reserves are
attributable to any acreage for which an application of fluid injection or other
improved technique is contemplated, only when such techniques have been proved
effective by actual tests in the area and in the same reservoir.
<PAGE>

HYDROCARBON PRICING PARAMETERS

SECURITIES AND EXCHANGE COMMISSION PARAMETERS


OIL AND CONDENSATE

     Edge furnished us with oil and condensate prices in effect at December 31,
1997 and these prices were held constant to depletion of the properties.  In
accordance with Securities and Exchange Commission guidelines, changes in liquid
prices subsequent to December 31, 1997 were not considered in this report.


PLANT PRODUCTS

     Edge furnished us with plant product prices in effect at December 31, 1997
and these prices were held constant to depletion of the properties.

GAS

     Edge furnished us with gas prices in effect at December 31, 1997 and with
its forecasts of future gas prices which take into account SEC guidelines,
current spot market prices, contract prices, and fixed and determinable price
escalations where applicable.  In accordance with SEC guidelines, the future gas
prices used in this report make no allowances for future gas price increases
which may occur as a result of inflation nor do they make any allowance for
seasonal variations in gas prices which may cause future yearly average gas
prices to be somewhat lower than December 31, 1997 gas prices.  For gas sold
under contract, the contract gas price including fixed and determinable
escalations, exclusive of inflation adjustments, was used until the contract
expires and then was adjusted to the current market price for the area and held
at this adjusted price to depletion of the reserves.