SECOND AMENDMENT TO
                  SECOND AMENDED AND RESTATED CREDIT AGREEMENT


     THIS SECOND  AMENDMENT TO SECOND AMENDED AND RESTATED  CREDIT  AGREEMENT is
dated and effective as of April 27, 2005 (this "Second 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, as amended by First Amendment thereto dated as of October
29,  2004 (as so  amended,  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 Second Amendment.

     B. REVISION TO DEFINED TERMS.

     1. The  following  new  definition  is hereby  added to Section  1.1 of the
Agreement:

          "SECOND  AMENDMENT" shall mean that certain Second Amendment
          to Second Amended and Restated Credit  Agreement dated as of
          April 27, 2005,  by and among the Borrower,  the  Guarantor,
          the Agent, and the Lenders.

                                  1


     C.  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:

          Commencing December 31, 2004:  $108,773,000 plus (i) 100% of
          all common and preferred equity  contributed by shareholders
          of Borrower  subsequent to December 31, 2004,  plus (ii) 50%
          of all positive  earnings  occurring  subsequent to December
          31, 2004.

          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.

     D.  RESTATEMENT  OF  SECTION  13.6(e).  Part  (e) of  Section  13.6  of the
Agreement is hereby deleted in its entirety and restated as follows:

          (e) Loans by the  Borrower  to the  Guarantor  and any other
          Subsidiary   of  Borrower   that  is  a  guarantor   of  the
          Indebtedness and/or capital contributions and/or investments
          by the Borrower in the Guarantor and any other Subsidiary of
          Borrower that is a guarantor of the Indebtedness;  provided,
          however,  the following loans,  investments,  and/or capital
          contributions  are  excluded  from  this  part  (e):  loans,
          investments, and/or capital contributions by the Borrower to
          the Guarantor  and/or any other  Subsidiary of Borrower that
          is a guarantor  of the  Indebtedness,  if the  Guarantor  or
          other  said  Subsidiary  uses  the  proceeds  of such  loan,
          contribution   or  investment  to  invest  in  Pinnacle  Gas
          Resources,  Inc. or any other entity in which the  Borrower,
          the  Guarantor  or  other  said  Subsidiary  owns an  equity
          interest.

     E.  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.

     F.  REPRESENTATIONS;  NO  DEFAULT.  On and as of the  date of  this  Second
Amendment,  and after giving effect to this Second  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 Second Amendment.

                                       2


     G. 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 the
transactions contemplated by this Second Amendment.

     H.  AMENDMENTS.  The Agreement and this Second 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 Second 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  Second
Amendment,  cannot  be  modified  or  amended  except by a  writing  signed  and
delivered by the Borrower, the Guarantor, the Agent and the Lenders.

     I. WAIVER OF DEFENSES.  In consideration of the Lenders'  execution of this
Second 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 Second Amendment.

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

     K. 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.

     L. 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 Second Amendment on behalf of Borrower and Guarantor.

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     IN WITNESS WHEREOF, the parties hereto have caused this Second 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