EXHIBIT 10.6

                               FIRST AMENDMENT TO
                  SECOND AMENDED AND RESTATED CREDIT AGREEMENT


     THIS FIRST  AMENDMENT TO SECOND  AMENDED AND RESTATED  CREDIT  AGREEMENT is
dated and  effective  as of October 29, 2004 (this  "First  Amendment"),  by and
among CARRIZO OIL & GAS, INC., a Texas corporation (the "Borrower"), CCBM, INC.,
a Delaware corporation (the "Guarantor"), and HIBERNIA NATIONAL BANK, a national
banking association,  individually as a Lender and as Administrative  Agent, and
UNION BANK OF CALIFORNIA, N.A., a national banking association,  individually as
a Lender and as Co-Agent.


                                    RECITALS:

     1. The Borrower, the Guarantor,  the Agent, and the Lenders have heretofore
entered into that certain Second Amended and Restated Credit  Agreement dated as
of  September  30,  2004  (the  "Agreement"),  pursuant  to  which  the  Lenders
established  in favor of  Borrower  a Line of  Credit  as more  fully  described
therein.

     2.  All  Loans  by  the  Lenders  to the  Borrower  are  guaranteed  by the
Guarantor.

     3. The parties desire to amend the Agreement as set forth herein.

     NOW,  THEREFORE,  the  parties  hereto,  in  consideration  of  the  mutual
covenants  hereinafter  set forth and intending to be legally  bound hereby,  do
hereby amend and supplement the Agreement as follows:

     A. Defined  Terms.  Capitalized  terms used herein which are defined in the
Agreement are used herein with such defined meanings, as said definitions may be
amended and/or supplemented by this First Amendment.

     B. Revision to Defined Terms.

     1. The definition of the term "Secured Subordinated Debt" in Section 1.1 of
the Agreement is hereby deleted and restated as follows:

          "Secured  Subordinated  Debt" shall mean  indebtedness of the Borrower
          (and any  Subsidiary of Borrower  that is a Guarantor)  outside of the
          Line  of  Credit,   issued  for  total  net  proceeds  not  to  exceed
          $28,000,000.00,  which  indebtedness  may bear  stated  cash  interest
          expense of up to 12% per annum (prior to default);  provided  that (i)
          the documents  governing  the issuance  thereof are entered into on or
          before December 31, 2004 (provided that additional notes may be issued
          thereunder  prior to October 29, 2006),  (ii) if such  indebtedness is
          secured  by a mortgage  lien on the  Mortgaged  Properties,  such lien
          shall be subordinate and inferior to


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          the Agent's mortgage lien on the Mortgaged  Properties,  and (iii) the
          Required  Lenders have reviewed and approved the  documents  governing
          said issuance.

     2. The  following  new  definitions  are hereby added to Section 1.1 of the
Agreement:

          "First  Amendment"  shall mean that certain First  Amendment to Second
          Amended and Restated Credit Agreement dated as of October 29, 2004, by
          and among the Borrower, the Guarantor, the Agent, and the Lenders.

          "Interest  Expense"  means,  for any period,  total  interest  expense
          (including that portion  attributable to capital lease  obligations in
          accordance with GAAP and capitalized interest) of the Borrower and its
          Subsidiaries (other than Unrestricted  Subsidiaries) on a consolidated
          basis with respect to all outstanding  Obligations of the Borrower and
          its Subsidiaries (other than Unrestricted  Subsidiaries) to the extent
          the  promissory  notes,  leases  or other  instruments  or  agreements
          evidencing  such  Obligations  require the payment of such interest in
          cash during such period.

          "Secured Subordinated Note Purchase Agreement" means the Note Purchase
          Agreement  dated as of  October  29,  2004  among  the  Borrower,  the
          Purchasers  (as  defined  therein)  and  PCRL  Investments,  L.P.,  as
          Collateral Agent, as amended, modified or restated from time to time.

          "Tangible  Net Worth"  means,  with  respect to any Person,  the total
          assets of such Person  (other than with respect to the  Borrower,  its
          Unrestricted Subsidiaries),  on a consolidated basis, exclusive of (a)
          those assets classified as intangible,  including, without limitation,
          goodwill, patents, trademarks, trade names, copyrights, franchises and
          deferred  charges,  (b) treasury  stock and minority  interests in any
          Person,  (c) cash set apart  and held in  sinking  or other  analogous
          funds established for the purpose of redemption or other retirement of
          capital  stock,  (d) to the extent  not  already  deducted  from total
          assets,  allowances for depreciation,  depletion,  obsolescence and/or
          amortization of properties, uncollectible accounts, and contingent but
          probable  liabilities  as to which an amount can be  established,  (e)
          deferred  taxes and (f) all assets  arising from advances to officers,
          former officers or sales  representatives of such Person or any of its
          Subsidiaries   (other  than  with   respect  to  the   Borrower,   its
          Unrestricted   Subsidiaries)  made  outside  the  ordinary  course  of
          business;  less total  liabilities of such Person and its Subsidiaries
          (other  than  with   respect  to  the   Borrower,   its   Unrestricted
          Subsidiaries),  on a  consolidated  basis,


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          all of the above being  determined in  accordance  with GAAP and, with
          respect  to the  Borrower,  excluding  the  effect  of any  cumulative
          after-tax  amounts  of  ceiling  test  write-downs  (not to  exceed an
          aggregate of $30  million)  incurred  subsequent  to December 31, 2001
          pursuant to Rule 4.10 of Regulation S-X promulgated by the Commission.

     C. Revised  Schedule  11.1.  Schedule  11.1 as attached to the Agreement is
hereby  deleted in its entirety and replaced  with the Schedule 11.1 attached to
this First Amendment.

     D.  Restatement of Section 11.21.  Section 11.21 of the Agreement is hereby
deleted in its entirety and restated as follows:

          Section 11.21. Security Agreement.  The Security Agreement constitutes
          a first  priority  security  interest  affecting  one hundred  percent
          (100%) of the issued and outstanding stock of the Guarantor, and there
          are no other Encumbrances affecting the said stock except as permitted
          by Section 13.4(r).

     E.  Restatement  of Section  12.8(d).  Section  12.8(d) of the Agreement is
hereby deleted in its entirety and restated as follows:

          (d) Minimum  Shareholder's  Equity. The Borrower shall maintain at all
          times a minimum shareholder's equity of not less than $100,000,000.00,
          plus  (i) 100% of all  common  and  preferred  equity  contributed  by
          shareholders of Borrower subsequent to June 30, 2004, plus (ii) 50% of
          all positive  earnings  occurring  subsequent  to June 30, 2004,  plus
          (iii)  180  days  after  Borrower's  issuance  of any  of the  Secured
          Subordinated Debt, an amount equal to 50% of the net proceeds from the
          issuance of any Secured  Subordinated  Debt;  provided,  however,  the
          minimum  shareholder's equity on and after April 30, 2005 shall be not
          less  than  $112,500,000.00.   For  purposes  of  this  covenant,  the
          calculation  of  Borrower's  "shareholder's  equity"  will exclude the
          effects,  if any, of ceiling test  write-downs  pursuant to Regulation
          SX4.10 of the Securities and Exchange Commission.

     F. Addition of New Affirmative  Covenants.  Article XII of the Agreement is
hereby  amended  and  supplemented  to include  the  following  new  affirmative
covenants as Section 12.8 (e) and Section 12.18, respectively:

          (e) EBITA to Interest Expense Ratio. The Borrower shall maintain as of
          the last day of each  fiscal  quarter a ratio of  EBITDA  for the four
          fiscal quarter period ending on such day to Interest  Expense for such
          period of at least 2.60 to 1.0.

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          Section  12.18.  Additional  Mortgaged  Properties.  (a) The  Borrower
          agrees to execute and deliver from time to time such  documents as are
          reasonably  requested by the Agent to provide that at least 90% of the
          net  present  value of the  proved oil and gas  reserves  owned by the
          Borrower  and  each  Guarantor,   taken  as  a  whole,  are  Mortgaged
          Properties,  excluding  Borrower's interests in the Camp Hill Field in
          East Texas.

          (b) In the event the Tangible Net Worth of any  Guarantor  (calculated
          with respect to CCBM without  including  the capital stock of Pinnacle
          so long as Pinnacle is not a Subsidiary of the Borrower) exceeds 3% or
          more of the Tangible  Net Worth of the Borrower and its  Subsidiaries,
          on a  consolidated  basis,  the Borrower shall cause such Guarantor to
          execute  and  deliver  to  Agent,  for the  benefit  of  each  Lender,
          Mortgages in form and  substance  reasonably  acceptable  to the Agent
          together  with  such  other  assignments,   conveyances,   amendments,
          agreements and other  writings (each duly  authorized and executed) as
          Agent  shall  reasonably  deem  necessary  or  appropriate  to  grant,
          evidence and perfect the  Encumbrances in the assets and properties of
          such  Guarantor  (provided  in no event  shall  the  capital  stock of
          Pinnacle be pledged so long as Pinnacle is not a Subsidiary).

     G.  Restatement  of Section  13.4(r).  Section  13.4(r) of the Agreement is
hereby deleted in its entirety and restated as follows:

          (r)  Encumbrances  affecting all or part of the Collateral that secure
          Secured  Subordinated  Debt  and  other  indebtedness  referred  to in
          Section 13.5(l) and such other  obligations  and  liabilities  related
          thereto, in each case, that is subject to, and permitted to be secured
          by, a written subordination  agreement executed by the Agent on behalf
          of the Lenders.

     H.  Restatement  of Section  13.5(l).  Section  13.5(l) of the Agreement is
hereby deleted in its entirety and restated as follows:

          (l)  Subject to the  provisions  of  Sections  10.2 and  13.4(r),  the
          indebtedness  evidenced by the Secured Subordinated Debt,  capitalized
          interest thereon,  and indebtedness  arising under hedging  agreements
          between  the  Borrower  and any  holder of such debt or any  affiliate
          thereof,  and  guarantees  executed  by  any  Subsidiary  of  Borrower
          guaranteeing payment thereof.

     I.  Restatement  of Section  13.7.  Section 13.7 of the Agreement is hereby
deleted in its entirety and restated as follows:

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          Section 13.7. Other Agreements.  Except as set forth in Schedule 11.1,
          the  Borrower  will  not  enter  into  any  agreement  containing  any
          provision  which would be violated or breached by the  performance  of
          its  obligations   hereunder  or  under  any  instrument  or  document
          delivered  or  to  be  delivered  by it  hereunder  or  in  connection
          herewith;  provided  that the Borrower may agree to the  redemption or
          repurchase of its securities  upon a change of control or dissolution,
          winding-up or liquidation  of, or the merger or sale of  substantially
          all the assets of, the Borrower (provided that nothing in this Section
          13.7 shall permit any action otherwise prohibited by Sections 13.1 and
          13.2 hereof).

     J.  Restatement of Section 13.11.  Section 13.11 of the Agreement is hereby
deleted in its entirety and restated as follows:

          Section 13.11.  Payments on Secured  Subordinated Debt. Subject to the
          terms and  conditions  of the  subordination  agreement  referenced in
          Section  10.2  above,  the  Borrower  agrees  that the only  scheduled
          payments  on the Secured  Subordinated  Debt due prior to the later of
          the stated  Facility  A  Termination  Date and the  stated  Facility B
          Termination  Date will be scheduled  interest  payments on  promissory
          notes evidencing Secured Subordinated Debt. In addition,  the Borrower
          agrees  to the  extent  it has the  discretion  to do so, to make said
          interest  payments by the issuance of debt or equity securities to the
          maximum  extent  permitted  by the  documents  evidencing  the Secured
          Subordinated  Debt;  provided,  however,  (i) during  such time as the
          Borrower  is  permitted  to make all or any  portion of said  interest
          payments  by the  issuance  of debt,  any  remaining  portion  of such
          interest payments may be paid in cash and (ii) the Borrower shall have
          no  obligation  to issue common stock in respect of any payment  under
          the Secured  Subordinated  Note Purchase  Agreement to the extent such
          issuance  would  require the  Borrower to issue common stock below the
          Floor  Price (as  defined in the Secured  Subordinated  Note  Purchase
          Agreement) for that payment.

     K. Consent by Lenders to Secured  Subordinated  Debt.  Subject to the terms
and conditions of that certain Subordination  Agreement of even date herewith by
and among the  Agent,  PCRL  Investments  L.P.  (as  Subordinate  Debt Agent and
Purchaser),  and Borrower, the Lenders do hereby permit the Secured Subordinated
Debt to be issued, and the liens contemplated  thereby to be granted by Borrower
pursuant to the Secured Subordinated Note Purchase Agreement,  and the execution
of the guarantees  contemplated  thereby, and authorize,  ratify and confirm the
Agent's  execution  of the  foregoing  Subordination  Agreement on behalf of the
Lenders.

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     L.  Confirmation of Related  Documents.  It is the intention of the parties
that all of the liens,  privileges,  priorities,  and  equities  existing and to
exist under and in accordance with the terms of the Related Documents are hereby
renewed,  extended,  and carried  forward as security for the  Indebtedness.  In
addition, the Guarantor hereby confirms its guaranty of the Indebtedness,  which
guaranty is evidenced by that certain  Commercial  Guaranty dated  September 30,
2004 by Guarantor in favor of Agent.

     M.  Representations;  No  Default.  On and as of the  date  of  this  First
Amendment, and after giving effect to this First Amendment, the Borrower and the
Guarantor confirm,  reaffirm, and restate the representations and warranties set
forth in the Agreement and the Loan Documents;  provided, that each reference to
the Agreement herein shall be deemed to include the Agreement as amended by this
First Amendment.

     N. Payment of Expenses.  The Borrower agrees to pay or reimburse the Lender
for all legal fees and expenses of counsel to the Agent in  connection  with (i)
the  transactions  contemplated by this First Amendment and (ii) a review of the
documentation for the Secured  Subordinated Debt and preparation of the required
subordination agreement.

     O.  Amendments.  The Agreement and this First  Amendment are credit or loan
agreements  as  described  in LA.  R.S.  6:ss.1121,  et seq.  There  are no oral
agreements between the Agent and Lenders and the Borrower and/or Guarantor.  The
Agreement, as amended by this First Amendment,  and the other Loan Documents set
forth the entire  agreement of the parties  with  respect to the subject  matter
hereof and  supersede  all prior  written  and oral  understandings  between the
Borrower, the Guarantor, the Agent, and the Lenders, with respect to the matters
herein and therein set forth. The Agreement, as amended by this First Amendment,
cannot be modified or amended  except by a writing  signed and  delivered by the
Borrower, the Guarantor, the Agent and the Lenders.

     P. Waiver of Defenses.  In consideration of the Lenders'  execution of this
First Amendment,  the Borrower and Guarantor do hereby irrevocably waive any and
all claims  and/or  defenses to payment on any  indebtedness  arising  under the
Agreement and owed by any of them to the Lender that may exist as of the date of
execution of this First Amendment.

     Q. Governing Law:  Counterparts.  The First  Amendment shall be governed by
and construed in accordance with the laws of the State of Louisiana.  This First
Amendment  may  be  executed  in  any  number  of  counterparts,  all  of  which
counterparts, when taken together, shall constitute one and the same instrument.

     R. Continued  Effect.  Except as expressly  modified herein,  the Agreement
shall  continue in full force and effect.  The  Agreement  as amended  herein is
hereby ratified and confirmed by the parties hereto.

     S. Reliance on Corporate Resolutions. The Borrower and the Guarantor hereby
certify to the Lenders that the  resolutions  delivered in  connection  with the
Agreement  remain in effect,  and that Paul F. Boling is  authorized  to execute
this First Amendment on behalf of Borrower and Guarantor.


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     IN WITNESS WHEREOF,  the parties hereto have caused this First Amendment to
be executed and delivered as of the date hereinabove  provided by the authorized
officers each hereunto duly authorized.

                                             Borrower:

                                             CARRIZO OIL & GAS, INC.
                                             a Texas corporation

                                             By:  /s/ Paul F. Boling
                                                 -------------------
                                                 Name:  Paul F. Boling
                                                 Title: Vice President and
                                                        Chief Financial Officer

                                             Guarantor:

                                             CCBM, INC.
                                             a Delaware corporation

                                             By:  /s/ Paul F. Boling
                                                 ------------------
                                                 Name: Paul F. Boling
                                                 Title: Vice President and
                                                        Chief Financial Officer

                                             Agent:

                                             HIBERNIA NATIONAL BANK, as Agent

                                             By:  /s/ David R. Reid
                                                  -----------------
                                                  Name: David R. Reid
                                                  Title:  Senior Vice President

                                             Lenders:

                                             HIBERNIA NATIONAL BANK

                                             By:  /s/ David R. Reid
                                                  -----------------
                                                  Name: David R. Reid
                                                  Title:  Senior Vice President

                                             UNION BANK OF CALIFORNIA, N.A.

                                             By:  /s/ Damien Meiburger
                                                  --------------------
                                                  Name: Damien Meiburger
                                                  Title:  Senior Vice President

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                                  Schedule 11.1

     Although  the  Borrower is not  required by the  documents  evidencing  the
Secured  Subordinated  Debt to issue  Capital  Stock in payment  of the  Secured
Subordinated Debt,  pursuant to such documents it has the option to do so. Under
certain circumstances the Borrower is required to repurchase such Capital Stock.
Such repurchase would violate Section 13.3 of the Agreement.