<PAGE>
 
                        RALPH E. DAVIS ASSOCIATES, INC.

                                    [LOGO]                           EXHIBIT 23A


                               February 11, 1997



CONSOLIDATED NATURAL GAS COMPANY
CNG Tower
625 Liberty Avenue
Pittsburgh, Pennsylvania   15222-3199

                       Report Covering Natural Gas Supply
                             And Owned Oil Reserves
                                December 31, 1996
                      ----------------------------------

Gentlemen:

          Consolidated Natural Gas Company, through its subsidiaries
(collectively Consolidated or the Company) is engaged in exploring for,
developing, producing, purchasing, gathering, transporting, storing and
distributing natural gas, together with by-product operations.  The principal
market area of the Company's retail operations is in Ohio, Pennsylvania,
Virginia and West Virginia.  Consolidated operates a regional interstate
pipeline system that supplies natural gas to affiliates, and to utilities and
end-users in the Midwest, Mid-Atlantic states and the Northeast.  Exploration
and production activities are carried on primarily in the Appalachian area, the
Gulf Coast area (including offshore), the Mid-Continent area, the Permian Basin
area, the Rocky Mountain area and in Canada.

          The history of the operations in the Appalachian area covers a period
of over 100 years.  Prior to l943, Consolidated's gas supply was obtained from
company-owned production and by purchase from fields located within the
Appalachian area.  From 1943 to 1993 Consolidated purchased gas from pipeline
companies which obtained their gas supply from fields in the Gulf Coast and
Southwest.  Since 1993, however, all remaining long-term gas purchase contracts
with pipelines have been replaced with firm transport contracts as the result of
Federal Energy Regulatory Commission (FERC) Order 636. Consolidated purchases
gas under contracts with producers and marketers, and also purchases gas on the
spot market. A substantial part of
<PAGE>
 
Consolidated Natural Gas Company                               February 11, 1997
                                                                          Page 2
 
these gas supplies are also obtained from fields in the Gulf Coast and
Southwest. Since 1957 Consolidated has also been engaged in exploration and
production of gas in Louisiana and the Texas Gulf Coast, including offshore.
During the twelve months ended December 31, 1996 most of the gas produced and
purchased by the Company was obtained from the Southwest. All gas volumes herein
are stated at a measuring base of 14.73 pounds per square inch absolute.

                           APPALACHIAN AREA RESERVES
                           -------------------------

          Studies of the natural gas available from Appalachian gas fields lead
us to conclude that the Company may expect to obtain for a number of years a
supply from this area.  The development which has occurred in this natural gas
province has resulted in extensive drilling of shallow formations in much of the
area.  The entire sedimentary section has not been adequately tested in the
Appalachian area and there is the possibility that natural gas is present in
commercial quantities below the known producing formations.  Consolidated has
participated in programs to test deeper formations.  Consolidated has also found
that reentry into old wells has been beneficial in finding commercial quantities
behind pipe.

          We estimate Consolidated's proved reserves in the Appalachian fields,
as of December 31, 1996, to be 300 billion cubic feet (including CNG Producing
Company's Appalachian reserves) from company-owned wells and 381 billion cubic
feet from gas purchase wells, for a total of 681 billion cubic feet, exclusive
of gas in storage reservoirs.  Total additions to the reserves controlled by the
Company in the Appalachian fields have in the past been substantial.  It is
possible that future exploration and development will locate appreciable new
reserves.  In addition, subsidiary companies had remaining working interest oil
reserves estimated at 393,161 barrels (including CNG Producing Company's
Appalachian oil reserves) in the Appalachian area.


                             CNG PRODUCING COMPANY
                             ---------------------

          CNG Producing Company is Consolidated's primary exploration and
production subsidiary.  As of December 31, 1996, the estimated proved working
interest reserves of CNG Producing Company are 892 billion cubic feet of gas and
50,273,717 barrels of crude oil and 
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Consolidated Natural Gas Company                               February 11, 1997
                                                                          Page 3
                                                              
condensate. The foregoing totals include approximately 1 billion cubic feet of
gas and 8,638,612 barrels of heavy oil reserves in Canada.

          In the United States, CNG Producing Company has proved reserves in 10
states and the offshore area of the Gulf Coast.  The majority of CNG Producing
Company's United States reserves are in the Gulf Coast and Mid-Continent areas.
The estimated proved reserves in the United States are 891 billion cubic feet of
gas and 41,635,105 barrels of crude oil and condensate.

          The estimated Appalachian proved reserves as of December 31, 1996 for
CNG Producing Company, which are included in the total Appalachian reserves
disclosed earlier in this report, are 109 billion cubic feet of gas and 101,350
barrels of oil.  In addition to the Appalachian area, CNG Producing Company
conducts exploration and development programs in other areas, including the San
Juan Basin in New Mexico.  The San Juan Basin has a history of oil and gas
production from conventional sources, but recent interest in the area stems from
an unconventional source of gas supply.  This interest is the Fruitland Coal
formation, where CNG Producing Company and others are producing gas from the
coal beds.  The estimated San Juan Basin proved reserves of CNG Producing
Company as of December 31, 1996 are 9 billion cubic feet.

                                 SOUTHWEST GAS
                                 -------------

          Consolidated's subsidiaries have gas supply contracts with various gas
producing companies and marketing groups with remaining terms ranging from a few
months to as long as eight (8) years.  Purchase entitlements under these
contracts total approximately 284 billion cubic feet, if all volumes are
requested.  This estimate gives no consideration to the estimated volumes of
spot market gas which may be purchased in the future.

                                  GAS STORAGE
                                  -----------

          The Company owns and operates 26 gas storage fields, five of which are
owned and operated jointly with other companies.  One storage field is owned and
operated jointly with Texas Eastern, one with Tennessee, one with North Penn
Gas, one with both Tennessee and 
<PAGE>
 
Consolidated Natural Gas Company                               February 11, 1997
                                                                          Page 4
 
National Fuel Gas Supply Corporation, and another with both Texas Eastern and
Transcontinental. Consolidated's net injected gas stored at December 31, 1996,
was 479 billion cubic feet (including 53 billion cubic feet of remaining non-
recoverable native gas, and 60 billion cubic feet of non-recoverable base gas.)

          The proximity of these storage fields to principal markets and their
high deliverability are important factors in enabling the Company to meet peak
loads and daily requirements during the heating season, and permit the gas
purchased to be taken relatively uniformly in summer and winter.

          There are additional depleted, or nearly depleted, gas fields in the
Appalachian area which can be converted to storage fields if needed.
 
                            POTENTIAL SUPPLY SOURCES
                            ------------------------

          In order to meet the demands for gas in its market area over the long-
term future, Consolidated may need additional supplies over those available from
the sources discussed above.

          Canadian authorities have increased the volumes of gas which may be
imported into the United States.  Gas presently being imported from Canada is
principally obtained from provinces in Western Canada.  In the future, the
availability of additional gas will probably be dependent on gas from frontier
areas such as the MacKenzie Basin - Beaufort Sea area and/or the Arctic Islands.
Such additional gas from Canada may be available in part to Consolidated
directly or through other suppliers.

          Other potential sources of gas include Alaska, Mexico, liquefied
natural gas from abroad, synthetic gas from coal or other feed stock and
additional coalbed methane.
 
                            SUMMARY AND CONCLUSIONS
                            -----------------------

          We have estimated proved working interest crude oil and condensate
reserves owned by Consolidated from sources in the United States and Canada at
50,565,528 barrels as of December 31, 1996 as follows:
<PAGE>
 
Consolidated Natural Gas Company                               February 11, 1997
                                                                          Page 5

<TABLE>
<CAPTION>
                                             Stock Tank Barrels
                                             ------------------
<S>                                          <C>
Appalachian Field Reserves                              291,811
--------------------------                 
 
CNG Producing Company
---------------------                           
  Southwest                                          50,172,367
  Appalachian                                           101,350
                                                     ----------
          Sub Total                                  50,273,717
 
TOTAL - OWNED OIL AND CONDENSATE RESERVES            50,565,528
</TABLE>

          We have estimated the gas reserves available to Consolidated from
sources in the United States and Canada at 2,227 billion cubic feet as of
December 31, 1996 as follows:
<TABLE>
<CAPTION>
                                     Billion
                                   Cubic Feet
                                  at 14.73 psia
                                  -------------
<S>                               <C>
Appalachian Field Reserves
--------------------------        
 
   Company-Owned Wells                  191
   Gas Purchase Contract Wells          381
   Gas in Storage Reservoirs            479
                                      -----
      Sub-Total                       1,051
                                   
CNG Producing Company Reserves     
------------------------------   
   Company-Owned Wells             
      Southwest                         783
      Appalachian                       109
                                      -----
         Sub-Total                      892
 
Gas Supply Contracts                    284
--------------------                                           

TOTAL - CONTROLLED GAS RESERVES       2,227

</TABLE>


          Consolidated's requirements for the twelve months ended December 31,
1996, including sales of gas produced in Canada, were approximately 744 billion
cubic feet, compared to requirements of 897 billion cubic feet in 1995.

          Additional supplies are expected to become available from the
Appalachian area, the Gulf Coast and other areas and from company-owned
reserves.
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Consolidated Natural Gas Company                               February 11, 1997
                                                                          Page 6

          Potential sources of supply include additional gas from Canada, Mexico
and Alaska, liquefied natural gas from abroad, gas from the reforming of liquid
hydrocarbons such as naphtha and oil, gas from coal gasification and coalbed
methane.

          The time at which these additional supplies will become available
cannot be definitely predicted.  However, Consolidated is in a favorable
position to secure gas supplies from many directions, including its proven
reserves, the volume of gas in underground storage, the prospects for additional
supplies from its traditional supply areas, the several potential supply sources
and the Company's own program to augment its supply.


                                  Yours very truly,

                                  RALPH E. DAVIS ASSOCIATES, INC.



                                  /s/ Thomas N. Sudderth
                                  ________________________________________
                                  Thomas N. Sudderth
                                  President

TNS:sw
<PAGE>
 
                        RALPH E. DAVIS ASSOCIATES, INC.

                                    [LOGO]

 
                                 March 21, 1997



                       CONSENT OF INDEPENDENT GEOLOGISTS
                       ---------------------------------


     We hereby consent to the use of our report dated February 11, 1997,
relating to the total gas supply and Company-owned oil and gas reserves of
Consolidated Natural Gas Company, to be filed as an Exhibit to Consolidated
Natural Gas Company's Annual Report on Form 10-K for the year ended December 31,
1996.  We further consent to the filing hereof as an Exhibit to said Annual
Report on Form 10-K.

     We also consent to the incorporation by reference into (i) the Registration
Statements on Form S-3 (Nos. 33-52585, 33-63931 and 333-10869) and Form S-8
(Nos. 2-77204, 2-97948, 33-40478, 33-44892 and 333-18783) of Consolidated
Natural Gas Company, and (ii) the prospectuses made a part thereof, of our
estimates of Company-owned oil and gas reserves in the United States and Canada
included in Consolidated Natural Gas Company's Annual Report on Form 10-K for
the year ended December 31, 1996.  We also consent to the references to us under
the heading "Experts" in such Prospectuses.


                              /s/ Thomas N. Sudderth
                              ____________________________________________
                              Thomas N. Sudderth