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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                AMENDMENT NO. 3

                                       TO
                                  SCHEDULE TO
                             TENDER OFFER STATEMENT
   under Section 14(d)(1) or 13(e)(1) of the Securities Exchange Act of 1934
                         BARRETT RESOURCES CORPORATION
                       (Name of Subject Company (issuer))
                            SRM ACQUISITION COMPANY
                               SHELL OIL COMPANY
                      (Names of Filing Persons (offerors))
                     COMMON STOCK, PAR VALUE $.01 PER SHARE
           (Including the Associated Preferred Stock Purchase Rights)
                         (Title of Class of Securities)
                                   068480201
                     (CUSIP Number of Class of Securities)

                                Lori M. Muratta
                                 Senior Counsel
                               Shell Oil Company
                                One Shell Plaza
                                 910 Louisiana
                              Houston, Texas 77002
                                 (713) 241-6161
  (Name, Address and Telephone Number of Person Authorized to Receive Notices
                and Communications on Behalf of Filing Persons)
                                    Copy to:
                             Joseph A. Cialone, II
                               Baker Botts L.L.P.
                                One Shell Plaza
                                 910 Louisiana
                           Houston, Texas 77002-4995
                                 (713) 229-1234

                           CALCULATION OF FILING FEE



            TRANSACTION VALUATION*                         AMOUNT OF FILING FEE**
            ----------------------                         ----------------------
                                            
              $1,967,152,550.00                                 $393,430.51


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*  For purposes of calculating amount of filing fee only. Based on the offer to
   purchase 35,766,410 shares of common stock, par value $.01 per share, of
   Barrett Resources Corporation, including the related preferred stock purchase
   rights, at a purchase price of $55.00 per share net to the seller in cash,
   without interest. Such number of shares represents the total of 33,055,586
   shares outstanding as of November 8, 2000 (as reported in Barrett Resources
   Corporation's Quarterly Report on Form 10-Q for the quarter ended September
   30, 2000), and the 2,710,824 shares issuable on exercise of options to
   purchase shares outstanding as of December 31, 1999 (as reported in Barrett
   Resources Corporation's Annual Report on Form 10-K for the year ended
   December 31, 1999).
** The amount of the filing fee calculated in accordance with Regulation
   240.0-11 of the Securities Exchange Act of 1934, as amended, equals 1/50th of
   one percent of the value of the transaction.
[X]  Check the box if any part of the fee is offset as provided by Rule
     0-11(a)(2) and identify the filing with which the offsetting fee was
     previously paid. Identify the previous filing registration statement
     number, or the Form or Schedule and the date of its filing.


                                                          
            Amount Previously Paid: $393,430.51              Filing Party: SRM Acquisition Company
                                                                         Shell Oil Company
            Form or Registration No.: Schedule TO            Date Filed: March 12, 2001


[ ] Check the box if the filing relates solely to preliminary communications
    made before the commencement of a tender offer.
  Check the appropriate boxes below to designate any transactions to which the
statement relates:
  [X] third-party tender offer subject to Rule 14d-1.
  [ ] issuer tender offer subject to Rule 13e-4.
  [ ] going-private transaction subject to Rule 13e-3.
  [ ] amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results
of the tender offer:  [ ]
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    This Amendment No. 3 to Tender Offer Statement on Schedule TO (the
"Amendment") amends and supplements the Tender Offer Statement on Schedule TO
filed with the Securities and Exchange Commission on March 12, 2001 (the
"Schedule TO"), as amended by Amendment No. 1 dated March 13, 2001 and Amendment
No. 2 dated March 15, 2001, by SRM Acquisition Company (the "Purchaser"), a
Delaware corporation and an indirect wholly owned subsidiary of Shell Oil
Company, a Delaware corporation ("Shell"), and Shell relating to the purchase of
(1) all outstanding shares of common stock, par value $.01 per share, of Barrett
Resources Corporation (the "Company") and (2) the associated preferred stock
purchase rights outstanding under the Rights Agreement dated as of August 5,
1997, as amended, between the Company and BankBoston, N.A., as Rights Agent (the
"Rights"), that are not owned by the Purchaser, Shell or Shell's other direct or
indirect subsidiaries, at a purchase price of $55.00 per share, net to the
seller in cash, without interest thereon, upon the terms and subject to the
conditions set forth in the Offer to Purchase dated March 12, 2001 and in the
related Letter of Transmittal (which, together with any amendments or
supplements thereto, collectively constitute the "Offer") that are annexed to
and filed with the Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B),
respectively. This Amendment is being filed on behalf of the Purchaser and
Shell.


ITEM 11. ADDITIONAL INFORMATION.


    On March 22, 2001, Shell issued a press release, a copy of which is filed as
Exhibit (a)(1)(P) hereto and is incorporated herein by reference.


ITEM 12. MATERIALS TO BE FILED AS EXHIBITS.

    Item 12 of the Schedule TO is hereby amended and supplemented as follows:



                      
       (a)(1)(A)         -- Offer to Purchase, dated March 12, 2001*
       (a)(1)(B)         -- Letter of Transmittal*
       (a)(1)(C)         -- Notice of Guaranteed Delivery*
       (a)(1)(D)         -- Letter to Brokers, Dealers, Commercial Banks, Trust
                           Companies and Other Nominees*
       (a)(1)(E)         -- Letter to Clients for Use by Brokers, Dealers, Commercial
                           Banks, Trust Companies and Other Nominees*
       (a)(1)(F)         -- Guidelines for Certification of Taxpayer Identification
                           Number of Substitute Form W-9*
       (a)(1)(G)         -- Press release issued by Shell Oil Company on March 12,
                           2001*
       (a)(1)(I)         -- Summary Advertisement, published March 12, 2001*
       (a)(1)(J)         -- Preliminary Consent Statement, filed March 12, 2001*
       (a)(1)(K)         -- Complaint filed in the United States District Court for
                           the District of Delaware on March 12, 2001*
       (a)(1)(L)         -- Amended Complaint filed in the Chancery Court, New Castle
                           County, Delaware on March 12, 2001*
       (a)(1)(M)         -- Transcript of Analysts Telephone Call dated March 7,
                           2001*
       (a)(1)(N)         -- Correspondence and Secretary's Certificate Certifying to
                           attached Resolutions of the Board of Directors of Barrett
                           Resources Corporation, dated March 14, 2001*
       (a)(1)(O)         -- Press release issued by Shell Oil Company on March 14,
                           2001*
       (a)(1)(P)         -- Press release issued by Shell Oil Company on March 22,
                           2001
       (b)               -- None
       (c)               -- None
       (d)               -- None
       (e)               -- None
       (f)               -- None
       (g)               -- None
       (h)               -- None



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* Previously filed as exhibits to Schedule TO

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                                   SIGNATURE

    After due inquiry and to the best of my knowledge and belief, I certify that
the information set forth in this statement is true, complete and correct.


Dated: March 23, 2001


                                            SRM ACQUISITION COMPANY

                                            By:  /s/ WALTER VAN DE VIJVER
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                                                     Walter van de Vijver
                                                President and Chief Executive
                                                            Officer

                                            SHELL OIL COMPANY

                                            By: Shell Exploration & Production
                                                Company,
                                                as agent

                                            By:  /s/ WALTER VAN DE VIJVER
                                              ----------------------------------
                                                     Walter van de Vijver
                                                President and Chief Executive
                                                            Officer

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                               INDEX OF EXHIBITS




      EXHIBIT NO.                                  DOCUMENT
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       (a)(1)(A)         -- Offer to Purchase, dated March 12, 2001*
       (a)(1)(B)         -- Letter of Transmittal*
       (a)(1)(C)         -- Notice of Guaranteed Delivery*
       (a)(1)(D)         -- Letter to Brokers, Dealers, Commercial Banks, Trust
                            Companies and Other Nominees*
       (a)(1)(E)         -- Letter to Clients for Use by Brokers, Dealers, Commercial
                            Banks, Trust Companies and Other Nominees*
       (a)(1)(F)         -- Guidelines for Certification of Taxpayer Identification
                            Number of Substitute Form W-9*
       (a)(1)(G)         -- Press release issued by Shell Oil Company on March 12,
                            2001*
       (a)(1)(I)         -- Summary Advertisement, published March 12, 2001*
       (a)(1)(J)         -- Preliminary Consent Statement, filed March 12, 2001*
       (a)(1)(K)         -- Complaint filed in the United States District Court for
                            the District of Delaware on March 12, 2001*
       (a)(1)(L)         -- Amended Complaint filed in the Chancery Court, New Castle
                            County, Delaware on March 12, 2001*
       (a)(1)(M)         -- Transcript of Analysts Telephone Call dated March 7,
                            2001*
       (a)(1)(N)         -- Correspondence and Secretary's Certificate Certifying to
                            attached Resolutions of the Board of Directors of Barrett
                            Resources Corporation, dated March 14, 2001*
       (a)(1)(O)         -- Press release issued by Shell Oil Company on March 14,
                            2001*
       (a)(1)(P)         -- Press release issued by Shell Oil Company on March 22,
                            2001
       (b)               -- None
       (c)               -- None
       (d)               -- None
       (e)               -- None
       (f)               -- None
       (g)               -- None
       (h)               -- None



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* Previously filed as exhibits to Schedule TO