-----------------------------
                                                            OMB APPROVAL
                                                   -----------------------------
                                                   OMB Number:         3235-0145
                                                   Expires:    December 31, 2005
                                                   Estimated average burden
                                                   hours per response......11.00
                                                   -----------------------------

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                 Information to be Included in Statements Filed
          Pursuant to Rule 13d-1(b), (c) and (d) and Amendments thereto
                         Filed Pursuant to Rule 13d-2(b)

                               (Amendment No. 5)*

                             Carrizo Oil & Gas, Inc.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    144577103
--------------------------------------------------------------------------------
                                 (CUSIP Number)


                                February 5, 2005
--------------------------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

      |_| Rule 13d-1(b)

      |_| Rule 13d-1(c)

      |X| Rule 13d-1(d)

      * The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which would
alter the disclosures provided in a prior cover page.

      The information required in the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act (however, see
the Notes).


                               Page 1 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103

--------------------------------------------------------------------------------
Names of Reporting Persons.
   1.     I.R.S. Identification Nos. of above persons (entities only).

          J.P. Morgan Partners (23A SBIC), L.P. (f/k/a J.P. Morgan Partners
          (23A SBIC), LLC)
          13-3986302
--------------------------------------------------------------------------------
   2.     Check the Appropriate Box if a Member of a Group (See Instructions)
                                                                         (a) |_|
                                                                         (b) |_|
--------------------------------------------------------------------------------
   3.     SEC Use Only
--------------------------------------------------------------------------------
   4.     Citizenship or Place of Organization
          Delaware

--------------------------------------------------------------------------------
 Number of                     5.  Sole Voting Power
 Shares Beneficially                              0
 Owned by Each                 -------------------------------------------------
 Reporting Person              6. Shared Voting Power
 With:                                            0
                               -------------------------------------------------
                               7. Sole Dispositive Power
                                                  0
                               -------------------------------------------------
                               8. Shared Dispositive Power
                                                  0 shares of Common Stock
--------------------------------------------------------------------------------
   9.     Aggregate Amount Beneficially Owned by Each Reporting Person

--------------------------------------------------------------------------------
  10.     Check if the Aggregate Amount in Row (9) Excludes Certain Shares
          (See Instructions)                                                 |_|
--------------------------------------------------------------------------------
  11.     Percent of Class Represented by Amount in Row (9)
                             0%
--------------------------------------------------------------------------------
  12.     Type of Reporting Person (See Instructions)
                             PN
--------------------------------------------------------------------------------

                               Page 2 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103

Preliminary Note: The information contained in this Schedule 13G has been filed
to reflect the sale by the Reporting Person of all of the shares of Common Stock
held by the Reporting Person.

Item 1.

      (a)   Name of Issuer:

            Carrizo Oil & Gas, Inc..

            Address of Issuer's Principal Executive Offices:

            14811 St. Mary's Lane, Suite 148, Houston, TX 77079.

Item 2.

      (a)   Name of Person Filing:

            J.P. Morgan Partners (23A SBIC), L.P.

            Supplemental information relating to the ownership
            and control of the person filing this statement is
            included in Exhibit 2(a) attached hereto.

      (b)   Address of Principal Business Office or, if none, Residence:

            1221 Avenue of the Americas
            New York, New York  10020

      (c)   Citizenship:

            Delaware

      (d)   Title of Class of Securities (of Issuer):

            Common Stock

      (e)   CUSIP Number:

            144577103

Item 3.  If this statement is filed pursuant to ss. ss. 240. 13d-1(b) or 240.
         13d-2(b) or (c), check whether the person filing is a:

            Not applicable.

Item 4. Ownership

      (a)   Amount Beneficially Owned: 0


                               Page 3 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103

(b)      Percent of Class:

                           0%

      (c)   Number of shares as to which such person has:

            (i)   0

            (ii)  Not applicable

            (iii) 0

            (iv)  Not applicable

Item 5. Ownership of Five Percent or Less of a Class

If this Statement is being filed to report the fact that as of the date hereof
the Reporting Person has ceased to be beneficial owner of more than five percent
of the class of securities, check the following. |X|

Item 6. Ownership of More than Five Percent on Behalf of Another Person

            Not applicable.

Item 7.  Identification and Classification of the Subsidiary Which Acquired the
         Security Being Reported on By the Parent Holding Company

            Not applicable.

Item 8.  Identification and Classification of Members of the Group

            Not applicable.

Item 9.  Notice of Dissolution of Group

            Not applicable.

Item 10. Certification

            Not applicable.


                               Page 4 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103


                                    SIGNATURE

      After reasonable 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.

Date:  February 14, 2005

                            J.P. MORGAN PARTNERS (23A SBIC), L.P.

                            By:  J.P. Morgan Partners (23A SBIC Manager)., Inc.,
                                    Its General Partner


                            By:  /s/ Jeffrey C. Walker
                                --------------------------------------------
                                Name:    Jeffrey C. Walker
                                Title:  President



                               Page 5 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103


                                  EXHIBIT 2(a)

This  statement  is being filed by J.P.  Morgan  Partners  (23A SBIC),  L.P.,  a
Delaware  limited  partnership  (hereinafter  referred to as "JPMP (23A  SBIC)")
whose principal business is located at 1221 Avenue of the Americas, New York, NY
10020.  JPMP (23A SBIC) is engaged in the venture  capital and leveraged  buyout
business.  The General  Partner of JPMP (23A SBIC) is J.P.  Morgan Partners (23A
SBIC Manager),  Inc., a Delaware corporation  (hereinafter  referred to as "JPMP
(23A Manager)"),  whose principal business office is located at the same address
as JPMP (23A SBIC).  JPMP (23A  Manager) is also engaged in the venture  capital
and leveraged buyout  business.  Set forth in Schedule A hereto and incorporated
herein by reference are the names, business addresses, principal occupations and
employment  of each  executive  officer and director of JPMP (23A  Manager).  As
general  partner  of JPMP  (23A  SBIC),  JPMP  (23A  Manager)  may be  deemed to
beneficially own the shares held by JPMP (23A SBIC).

JPMP (23A Manager) is a wholly owned  subsidiary  of JPMorgan  Chase Bank, a New
York National Association, a National Banking Association, (hereinafter referred
to as "JPMChase Bank") which is engaged in the commercial  banking business with
its principal  office located at 270 Park Avenue,  New York, New York 10017. Set
forth in Schedule B hereto and  incorporated  herein by reference are the names,
business  addresses,  principal  occupations  and  employments of each executive
officer and director of JPMChase Bank.

Chase Bank is a wholly  owned  subsidiary  of  JPMorgan  Chase & Co., a Delaware
corporation  (hereinafter  referred  to as "JP Morgan  Chase")  which is engaged
(primarily  through  subsidiaries)  in the commercial  banking business with its
principal office located at 270 Park Avenue, New York, New York 10017. Set forth
in  Schedule  C hereto  and  incorporated  herein by  reference  are the  names,
business  addresses,  principal  occupations  and  employments of each executive
officer and director of JP Morgan Chase.


                               Page 6 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103

                                                                      SCHEDULE A

                 J.P. MORGAN PARTNERS (23 A SBIC MANAGER), INC.

                              Executive Officers(1)

President                                             Jeffrey C. Walker*
Chief Investment Officer                              Arnold L. Chavkin*
Managing Director                                     Srinivas Akkaraju*
Managing Director                                     Christopher Albinson*
Managing Director                                     Dr. Dana Beth Ardi*
Managing Director                                     Richard Aube*
Managing Director                                     Christopher C. Behrens*
Managing Director                                     John Breckenridge*
Managing Director                                     Julie Casella-Esposito*
Managing Director                                     Rodney A. Ferguson*
Managing Director                                     Cornell P. French*
Managing Director                                     Michael R. Hannon*
Managing Director                                     Matthew Lori*
Managing Director                                     Jonathan R. Lynch*
Managing Director                                     Bryan Martin*
Managing Director                                     Sunil Mishra*
Managing Director                                     Stephen P. Murray*
Managing Director                                     Timothy Purcell*
Managing Director                                     John Reardon*
Managing Director                                     Faith Rosenfeld*
Managing Director                                     Shahan D. Soghikian*
Managing Director                                     William Stuck*
Managing Director                                     Patrick J. Sullivan*
Managing Director                                     Timothy J. Walsh*
Managing Director                                     Richard D. Waters, Jr. *
Managing Director                                     Damion E. Wicker, M.D.*


                                   Directors*

                               Jeffrey C. Walker*

--------

(1)   Each of whom is a United States citizen.
*     Principal occupation is employee and/or officer of J.P. Morgan Partners,
      LLC. Business address is c/o J.P. Morgan Partners, LLC, 1221 Avenue of the
      Americas, New York, New York 10020.

                               Page 7 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103

                                                                      SCHEDULE B

                    JPMORGAN CHASE BANK, NATIONAL ASSOCIATION

                              Executive Officers(1)

Chairman of the Board and Chief Executive Officer       William B. Harrison Jr.*
President and Chief Operating Officer                   James Dimon*
Chief Information Officer                               Austin A. Adams*
Co-Chairman, Investment Bank                            Steven D. Black*
Chief Executive Officer, Card Services                  William I. Campbell*
Chief Financial Officer                                 Michael J. Cavanagh*
Chairman, West Coast Region                             David A. Coulter*
Director of Human Resources, Head of Real
 Estate/Facilities, General Services, Security          John J. Farrell*
Co-General Counsel                                      Joan Guggenheimer*
Director of Corporate Marketing and Communications      Frederick W. Hill*
Head, Commercial Banking                                Samuel Todd Maclin*
Head, Strategy and Business Development                 Jay Mandelbaum*
Co-General Counsel                                      William H. McDavid*
Chief Executive Officer, Treasury & Securities
 Services                                               Heidi Miller*
Head, Retail Financial Services                         Charles W. Scharf*
Executive Vice President, Card Services                 Richard J. Srednicki*
Head, Asset & Wealth Management                         James E. Staley*
Chief Risk Officer                                      Don M. Wilson III*
Co-Chairman, Investment Bank                            William T. Winters*

----------

(1)   Each of whom is a United States citizen.
*     Principal occupation is employee or officer of JPMorgan Chase & Co.
      Business address is c/o JPMorgan Chase & Co., 270 Park Avenue, New York,
      New York 10017.


                               Page 8 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103


                                   Directors(1)

 Name                              Principal Occupation or Employment;
                                   Business or Residence Address
--------------------------------------------------------------------------------
 William B. Harrison, Jr.          Chairman and Chief Executive Office
                                   JPMorgan Chase & Co.
                                   270 Park Avenue
                                   New York, New York 10017
--------------------------------------------------------------------------------
 James Dimon                       President and Chief Operating Officer
                                   JPMorgan Chase & Co.
                                   270 Park Avenue
                                   New York, New York 10017
--------------------------------------------------------------------------------
 David A. Coulter                  Chairman, West Coast Region
                                   JPMorgan Chase & Co.
                                   270 Park Avenue
                                   New York, New York 10017
--------------------------------------------------------------------------------
 Michael J. Cavanaugh              Chief Financial Officer
                                   JPMorgan Chase & Co.
                                   270 Park Avenue
                                   New York, New York 10017
--------------------------------------------------------------------------------
 Charles W. Scharf                 Head of Retail Financial Services
                                   JPMorgan Chase & Co.
                                   270 Park Avenue
                                   New York, New York 10017
--------------------------------------------------------------------------------
 Don M. Wilson III                 Chief Risk Officer
                                   JPMorgan Chase & Co.
                                   270 Park Avenue
                                   New York, New York 10017
--------------------------------------------------------------------------------

----------
(1)   Each of whom is a United States citizen.


                               Page 9 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103

                                                                      SCHEDULE C


                              JPMORGAN CHASE & CO.

                              Executive Officers(1)

Chairman of the Board and Chief Executive Officer       William B. Harrison Jr.*
President and Chief Operating Officer                   James Dimon*
Chief Information Officer                               Austin A. Adams*
Co-Chairman, Investment Bank                            Steven D. Black*
Chief Executive Officer, Card Services                  William I. Campbell*
Chief Financial Officer                                 Michael J. Cavanagh*
Chairman, West Coast Region                             David A. Coulter*
Director of Human Resources, Head of Real
 Estate/Facilities, General Services, Security          John J. Farrell*
Co-General Counsel                                      Joan Guggenheimer*
Director of Corporate Marketing and Communications      Frederick W. Hill*
Head, Commercial Banking                                Samuel Todd Maclin*
Head, Strategy and Business Development                 Jay Mandelbaum*
Co-General Counsel                                      William H. McDavid*
Chief Executive Officer, Treasury & Securities
 Services                                               Heidi Miller*
Head, Retail Financial Services                         Charles W. Scharf*
Executive Vice President, Card Services                 Richard J. Srednicki*
Head, Asset & Wealth Management                         James E. Staley*
Chief Risk Officer                                      Don M. Wilson III*
Co-Chairman, Investment Bank                            William T. Winters*


                                  Directors(1)


 Name                                Principal Occupation or Employment;
                                     Business or Residence Address
--------------------------------------------------------------------------------
 Hans W. Becherer                    Retired Chairman of the Board and
                                     Chief Executive Officer
                                     Deere & Company
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------

----------
(1)   Each of whom is a United States citizen.
*     Principal occupation is employee or officer of JPMorgan Chase & Co.
      Business address is c/o JPMorgan Chase & Co., 270 Park Avenue, New York,
      New York 10017.
(1)   Each of whom is a United States citizen.


                               Page 10 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103



 Name                                Principal Occupation or Employment;
                                     Business or Residence Address
--------------------------------------------------------------------------------
 John H. Biggs                       Former Chairman and CEO
                                     TIAA - CREF
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
 Lawrence A. Bossidy                 Retired Chairman of the Board
                                     Honeywell International Inc.
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
 Stephen B. Burke                    President
                                     Comcast Cable Communications, Inc.
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
James S. Crown                       President
                                     Henry Crown and Company
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
James Dimon                          President and Chief Operating Officer
                                     JPMorgan Chase & Co.
                                     270 Park Avenue, 8th Floor
                                     New York, New York 10017-2070
--------------------------------------------------------------------------------
Ellen V. Futter                      President and Trustee
                                     American Museum of Natural History
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
 William H. Gray, III                Retired President and Chief Executive
                                     Officer
                                     The College Fund/UNCF
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
 William B. Harrison, Jr.            Chairman of the Board and Chief Executive
                                     Officer
                                     JPMorgan Chase & Co.
                                     270 Park Avenue, 8th Floor
                                     New York, New York  10017-2070
--------------------------------------------------------------------------------
 Laban P. Jackson, Jr.               Chairman and Chief Executive Officer
                                     Clear Creek Properties, Inc.
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017


                               Page 11 of 12 pages


                                    SCHEDULE 13G
Issuer: Carrizo Oil & Gas, Inc.                             CUSIP No.: 144577103


 Name                                Principal Occupation or Employment;
                                     Business or Residence Address
--------------------------------------------------------------------------------
 Lee R. Raymond                      Chairman of the Board and Chief Executive
                                     Officer
                                     Exxon Mobil Corporation
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
 John W. Kessler                     Owner
                                     John W. Kessler Company
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
 Robert I. Lipp                      Chairman
                                     The St. Paul Travelers Companies, Inc.
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
 Richard A. Monoogian                Chairman and Chief Executive Officer
                                     Masco Corporation
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
 David C. Novak                      Chairman and Chief Executive Officer
                                     Yum! Brands, Inc.
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------
 John R. Stafford                    Retired Chairman of the Board
                                     Wyeth
                                     c/o JPMorgan Chase & Co.
                                     270 Park Avenue
                                     New York, New York 10017
--------------------------------------------------------------------------------


                               Page 12 of 12 pages