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                                                                     EXHIBIT 4.1


                                SEVENTH AMENDMENT
                                       TO
              FIRST AMENDED, RESTATED, AND COMBINED LOAN AGREEMENT
                     BY AND BETWEEN CARRIZO OIL & GAS, INC.
                                AND COMPASS BANK


         This Seventh Amendment to the Loan Agreement (this "Seventh Amendment")
by and between CARRIZO OIL & GAS, INC., a Texas corporation (the "Borrower"),
and COMPASS BANK, an Alabama state chartered bank, formerly a Texas chartered
bank (the "Bank"), is entered into on this 27th day of August 1999, and shall be
effective as of that date for all purposes.

                              W I T N E S S E T H:

         Borrower and Bank entered into a First Amended, Restated, and Combined
Loan Agreement dated August 28, 1997, as amended by the First Amendment thereto
dated December 23, 1997, the Second Amendment thereto dated December 30, 1997,
the Third Amendment thereto dated July 30, 1998, the Fourth Amendment thereto
dated September 24, 1998, the Fifth Amendment thereto dated March 22, 1999 and
the Sixth Amendment thereto dated April 23, 1999 (collectively, the "Loan
Agreement"). Capitalized terms used, but not defined herein, shall have the
meanings prescribed therefor in the Loan Agreement.

         Borrower has requested that the Loan Agreement be further amended and
that the Bank waive Borrower's noncompliance with certain covenants in the Loan
Agreement, and the Bank has agreed to such request, subject to the terms and
conditions set forth in this Seventh Amendment.

         NOW, THEREFORE, in consideration of the mutual promises herein
contained, and for other good and valuable consideration, the receipt and
sufficiency of which are acknowledged by Borrower and Bank, and each intending
to be legally bound hereby, the parties agree as follows:

         I.       Specific Amendments to Loan Agreement.

         Article I, Definitions, is hereby amended by adding the following
definitions thereto:

                  "Metro Prospect" means those certain Oil and Gas Properties
         described in Schedule B attached to the Seventh Amendment.

                  "Seventh Amendment" means the Seventh Amendment to this
         Agreement executed by Borrower and Bank on August 27, 1999.

         Section 2.09, Mandatory Prepayment of the Notes, is hereby amended by
adding the following text at the end of such Section:


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                  Notwithstanding the foregoing provisions of this Section,
                  however, at the time that each Monthly Borrowing Base
                  Reduction becomes applicable on the first day of each calendar
                  month, Borrower shall contemporaneously prepay so much of the
                  principal of the Note as is necessary to ensure that no Loan
                  Excess results from the application of such Monthly Borrowing
                  Base Reduction.

         Subsection 2.10(a), Borrowing Base Oil and Gas Properties, is hereby
amended by replacing the first sentence of that section with the following text:

                  The Borrowing Base attributable to the Borrowing Base Oil and
                  Gas Properties is established at $3,750,000.00 effective as of
                  August 2, 1999, and continuing until redetermined as set forth
                  herein; provided, however, that the Borrowing Base value
                  attributable to the Borrowing Base Oil and Gas Properties
                  shall be reduced to $300,000.00 at the earlier of: (i) the
                  consummation of the sale by Borrower of the Metro Prospect or
                  (ii) October 1, 1999. The proceeds derived by Borrower from
                  any such sale of the Metro Prospect may be included in the
                  Borrowing Base as Borrowing Base Cash, provided that such
                  proceeds are deposited into an account that has been
                  specifically pledged to Bank pursuant to a Security Instrument
                  that is acceptable to Bank, in its discretion.

         Subsection 2.10(c), Borrowing Base Securities, is hereby amended by
adding the following sentence at the end of that subsection:

                  Notwithstanding the foregoing, the Borrowing Base value
                  attributable to Borrowing Base Securities that are shares of
                  stock in R&B Falcon Corporation shall never exceed at any time
                  $5,000,000.00 in the aggregate.

         Article III, Conditions, is hereby amended by adding the following
Section 3.21.

                  3.21 Conditions Precedent in Connection with the Seventh
         Amendment. The Seventh Amendment shall not be binding on the Bank until
         satisfaction of the following conditions precedent:

                  (a) Receipt of Seventh Amendment and Compliance Certificate.
         Bank shall have received multiple counterparts of the Seventh
         Amendment, as requested by Bank, and the Compliance Certificate duly
         executed by an authorized officer for Borrower.

                  (b) Accuracy of Representations and Warranties and No Event of
         Default. The representations and warranties contained in Article IV of
         the Loan Agreement shall be true and correct in all material respects
         on the date of the Seventh Amendment with the same effect as though
         such representations and warranties had been made on such date; and no
         Event of Default shall have occurred and be continuing or will have
         occurred upon the execution of the Seventh Amendment.


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                  (c) Legal Matters Satisfactory to Special Counsel to Bank. All
         legal matters incident to the consummation of the transactions
         contemplated by the Seventh Amendment shall be satisfactory to the firm
         of Porter & Hedges, L.L.P., special counsel for Bank.

                  (d) No Material Adverse Change. No material adverse change
         shall have occurred since the date of this Agreement in the condition,
         financial or otherwise, of Borrower.

         Article V, Affirmative Covenants, is hereby amended by adding the
following new Sections 5.29 through 5.36:

                  5.29 Proceeds from Hedging Transactions. Following the
         occurrence and during the continuation of an Event of Default or
         Unmatured Event of Default, if and so long as there is then Loan
         availability under that part of the Revolving Commitment that is
         supported by the Borrowing Base attributable to the Borrowing Base Oil
         and Gas properties (in excess of $300,000 of coverage for outstanding
         Letters of Credit), promptly deliver to Bank one hundred percent (100%)
         of all proceeds received by Borrower or, if not received, cause to be
         delivered to Bank all proceeds which Borrower is entitled to receive
         arising from the early termination of any Hedging Transaction, such
         proceeds to be applied against the outstanding balance owing on the
         Notes.

                  5.30 Hedging Transaction Reports. If and so long as there is
         then Loan availability under that part of the Revolving Commitment that
         is supported by the Borrowing Base attributable to the Borrowing Base
         Oil and Gas properties (in excess of $300,000 of coverage for
         outstanding Letters of Credit), for each Hedging Transaction to which
         Borrower is a party, if any, deliver to Bank, on or before the
         forty-fifth (45th) day after the end of each calendar month, a detailed
         report setting out Borrower's position as of the end of such calendar
         month, including, but not limited to, Borrower's settlement payments
         and receipts during such calendar month and settlement payables and
         receivables as of the end of such calendar month.

                  5.31 Aged Accounts Reports. Deliver to Bank, on or before the
         forty-fifth (45th) day after the end of each calendar month, a detailed
         aging accounts receivable report and a detailed aging accounts payable
         report effective as of the end of such calendar month, all such reports
         to be prepared in accordance with GAAP.

                  5.32 Production Volume Reports. If and so long as there is
         then Loan availability under that part of the Revolving Commitment that
         is supported by the Borrowing Base attributable to the Borrowing Base
         Oil and Gas Properties (in excess of $300,000 of coverage for
         outstanding Letters of Credit), deliver to Bank, on or before the
         forty-fifth (45th) day after the end of each calendar month, a monthly
         report of oil, gas and liquids production volumes by major field and
         the total production of all fields during such calendar month.

                  5.33 Payment of Contract Operators. Pay, within thirty (30)
         days after the receipt of any billings or sooner if so required by the
         terms of any applicable operating agreement, all fees, expenses and
         charges due from Borrower to contract operators (as such term is


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         generally understood in the oil and gas industry) for operations
         provided by contract operators relating to the Borrowing Base Oil and
         Gas Properties, except any such fees that are diligently being
         contested in good faith by appropriate proceedings.

                  5.34 Payment of Royalties. If and so long as there is then
         Loan availability under that part of the Revolving Commitment that is
         supported by the Borrowing Base attributable to the Borrowing Base Oil
         and Gas properties (in excess of $300,000 of coverage for outstanding
         Letters of Credit), pay, within sixty (60) days after the last day of
         each calendar month or sooner if so required by any applicable lease or
         statute, all royalties, overriding royalties, production payments or
         other payments payable by Borrower to the owners of such interests in
         the Borrowing Base Oil and Gas Properties with respect to oil and gas
         produced during such calendar month, unless Borrower has created and
         maintains a suspense account for separate accounting of any such
         payments that are payable but not yet due under the terms of the
         applicable lease and applicable laws. Any such payments made into such
         suspense account shall be accounted for in accordance with all
         applicable laws of the state in which the Borrowing Base Property to
         which such payment relates is located.

                  5.35 Payment of Royalties Reports. If and so long as there is
         then Loan availability under that part of the Revolving Commitment that
         is supported by the Borrowing Base attributable to the Borrowing Base
         Oil and Gas Properties (in excess of $300,000 of coverage for
         outstanding Letters of Credit), deliver to Bank, on or before the
         sixtieth (60th) day after the end of each calendar month, a monthly
         report of royalties, overriding royalties, production payments or other
         payments paid by Borrower to the owners of such interests (or into a
         suspense account as described in Section 5.34) in the Borrowing Base
         Oil and Gas Properties with respect to oil and gas produced during such
         calendar.

                  5.36 Proceeds from Asset Sales. Following the occurrence and
         during the continuation of an Event of Default or Unmatured Event of
         Default, promptly deliver to Bank one hundred percent (100%) of all
         proceeds received by Borrower or, if not received, cause to be
         delivered to Bank all proceeds which Borrower is entitled to receive
         arising from any sale of Borrower's assets, such proceeds to be applied
         against the outstanding balance owing on the Notes; provided that any
         such sale of assets must be made in compliance with Section 6.06
         hereof.

         Section 6.01, Other Indebtedness, is hereby amended by deleting the
word "and" immediately preceding clause (d) and adding the following clause (e)
at the end of that Section:

                  and (e) as of the effective date of the Seventh Amendment, the
                  Indebtedness evidenced by those certain vendor notes as
                  specifically described on Schedule A attached to the Seventh
                  Amendment.

         II.      Certain Waivers. Bank hereby waives non-compliance by Borrower
with the covenants set forth Section 6.01 of the Loan Agreement, solely to the
extent that Borrower was not in compliance with such covenants prior to the
execution of the Seventh Amendment as the result of the existence of the
Indebtedness evidenced by those certain vendor notes described on Schedule A
attached to the Seventh Amendment.


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         III.     Reaffirmation of Representations and Warranties. To induce
Bank to enter into this Seventh Amendment, Borrower hereby reaffirms, as of the
date hereof, its representations and warranties contained in Article IV of the
Loan Agreement and in all other documents executed pursuant thereto, and
additionally represents and warrants as follows:

                  A. The execution and delivery of this Seventh Amendment and
         the performance by Borrower of its obligations under this Seventh
         Amendment are within Borrower's power, have been duly authorized by all
         necessary corporate action, have received all necessary governmental
         approval (if any shall be required), and do not and will not contravene
         or conflict with any provision of law or of the articles of
         incorporation, charter or bylaws of Borrower or of any agreement
         binding upon Borrower.

                  B. The Loan Agreement as amended by this Seventh Amendment,
         represents the legal, valid and binding obligations of Borrower,
         enforceable against Borrower in accordance with its terms, subject as
         to enforcement only to bankruptcy, insolvency, reorganization,
         moratorium or other similar laws affecting the enforcement of
         creditors' rights generally.

                  C. No Event of Default or Unmatured Event of Default has
         occurred and is continuing as of the date hereof.

         IV.      Defined Terms. Except as amended hereby, terms used herein
that are defined in the Loan Agreement shall have the same meanings in this
Seventh Amendment.

         V.       Reaffirmation of Loan Agreement. This Seventh Amendment shall
be deemed to be an amendment to the Loan Agreement, and the Loan Agreement, as
further amended hereby, is hereby ratified, approved and confirmed in each and
every respect. All references to the Loan Agreement herein and in any other
document, instrument, agreement or writing shall hereafter be deemed to refer to
the Loan Agreement as amended hereby.

         VI.      Entire Agreement. The Loan Agreement, as hereby further
amended, embodies the entire agreement between Borrower and Bank and supersedes
all prior proposals, agreements and understandings relating to the subject
matter hereof. Borrower certifies that it is relying on no representation,
warranty, covenant or agreement except for those set forth in the Loan Agreement
as hereby further amended and the other documents previously executed or
executed of even date herewith.

         VII.     Governing Law. THIS SEVENTH AMENDMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS AND THE APPLICABLE
LAWS OF THE UNITED STATES OF AMERICA. This Seventh Amendment has been entered
into in Harris County, Texas, and it shall be performable for all purposes in
Harris County, Texas. Courts within the State of Texas shall have jurisdiction
over any and all disputes between Borrower and Bank, whether in law or equity,
including, but not limited to, any and all disputes arising out of or relating
to this Seventh Amendment or any other Loan Document; and venue in any such
dispute whether in federal or state court shall be laid in Harris County, Texas.


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         VIII.    Severability. Whenever possible each provision of this Seventh
Amendment shall be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Seventh Amendment shall be
prohibited by or invalid under applicable law, such provision shall be
ineffective to the extent of such prohibition or invalidity, without
invalidating the remainder of such provision or the remaining provisions of this
Seventh Amendment.

         IX.      Execution in Counterparts. Each party hereto acknowledges that
this Agreement may be executed in several counterparts by each party at
different times and in different locations; that each separate counterpart
bearing the signature of any party may be effectively delivered to the other
parties by the delivery of an electronic facsimile sent via telecopier; that
each party so delivering any such counterpart shall be bound by its facsimile
signature thereon; and that the signature pages from counterparts signed by each
party may be collated into one or more copies of this agreement, which shall
constitute one and the same agreement among all parties hereto.

         X.       Section Captions. Section captions used in this Seventh
Amendment are for convenience of reference only, and shall not affect the
construction of this Seventh Amendment.

         XI.      Successors and Assigns. This Seventh Amendment shall be
binding upon Borrower and Bank and their respective successors and assigns, and
shall inure to the benefit of Borrower and Bank, and the respective successors
and assigns of Bank.

         XII.     Non-Application of Chapter 346 of Texas Finance Codes. In no
event shall Chapter 346 of the Texas Finance Code (which regulates certain
revolving loan accounts and revolving tri-party accounts) apply to this Loan
Agreement as hereby further amended or any other Loan Documents or the
transactions contemplated hereby.

         XIII.    Notice. THIS SEVENTH AMENDMENT TOGETHER WITH THE LOAN
AGREEMENT, AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN
THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR
SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL
AGREEMENTS BETWEEN THE PARTIES.



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         IN WITNESS WHEREOF, the parties hereto have caused this Seventh
Amendment to be duly executed as of the day and year first above written.


BANK                                        BORROWER

COMPASS BANK                                     CARRIZO OIL & GAS, INC.


By:                                         By:
   --------------------------------            --------------------------------
    Kathleen J. Bowen                            Frank A. Wojtek
    Vice President                               Vice President


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                                  SCHEDULE "A"

                                  Vendor Notes

                               See attached pages.





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                                  SCHEDULE "B"

                           Metro Prospect Description

                              PROPERTY DESCRIPTION

I.       WELLS-DEWITT COUNTY, TEXAS



==============================================================================================================
   WELL NAME             PROPERTY                   INTEREST                  WORKING          NET REVENUE
                        DESCRIPTION                  HOLDER                  INTEREST           INTEREST
                                                                            PERCENTAGE         PERCENTAGE
- --------------------------------------------------------------------------------------------------------------
                                                                                   

Musselman          Rambler       Field      Carrizo Oil and Gas, Inc.         25.0000           18.2500
Wells              (Metro)

==============================================================================================================



II.      LEASES-DEWITT COUNTY, TEXAS

Oil, Gas and Mineral Lease dated January 21, 1997, between Musselman Ranches,
Inc., Jamie B. Musselman, President, Josephine B. Musselman, Paul A. Musselman
and wife Dorothy Musselman, and Eleanor G. Musselman, as Lessors, and Allegro
Investments, Inc., as lessee, and Memorandum of Lease effective January 21,
1997, between the same parties, recorded in Volume 18, Page 555, Official
Records, DeWitt County, Texas.



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                             COMPLIANCE CERTIFICATE


                  I, Frank A. Wojtek, Vice President of CARRIZO OIL & GAS, INC.
(the "Company"), pursuant to Section 3.20 of the First Amended, Restated, and
Combined Loan Agreement dated as of August 28, 1997, as amended, by and among
COMPASS BANK ("Bank") and the Company (the "Agreement") do hereby certify, as of
the date hereof, that to my knowledge:

         1.       No Event of Default (as defined in the Agreement) has occurred
                  and is continuing, and no Unmatured Event of Default (as
                  defined in the Agreement) has occurred and is continuing;

         2.       No material adverse change has occurred in the business
                  prospects, financial condition, or the results of operations
                  of the Company since the date of the previous Financial
                  Statements (as defined in the Agreement) provided to Bank;

         3.       Each of the representations and warranties of the Company
                  contained in Article IV of the Agreement is true and correct
                  in all respects.

                  This certificate is executed this 27th day of August 1999.





                                              ---------------------------------
                                                  Frank A. Wojtek




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