Exhibit 10.1

SECOND AMENDMENT

TO

CREDIT AGREEMENT

DATED AS OF SEPTEMBER 4, 2012

AMONG

CARRIZO OIL & GAS, INC.,

AS BORROWER,

WELLS FARGO BANK, NATIONAL ASSOCIATION,

AS ADMINISTRATIVE AGENT,

AND

THE LENDERS PARTY HERETO

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SECOND AMENDMENT TO CREDIT AGREEMENT

THIS SECOND AMENDMENT TO CREDIT AGREEMENT (this “Second Amendment”) dated as of
September 4, 2012, among CARRIZO OIL & GAS, INC., a Texas corporation (the
“Borrower”); the Lenders listed on the signature pages hereto; and WELLS FARGO
BANK, NATIONAL ASSOCIATION, as administrative agent for the Lenders (in such
capacity, together with its successors in such capacity, the “Administrative
Agent”).

R E C I T A L S

WHEREAS, the Borrower, the Administrative Agent, the Lenders and the other
Agents party thereto are parties to that certain Credit Agreement dated as of
January 27, 2011 (as heretofore amended, supplemented or otherwise modified, the
“Credit Agreement”), pursuant to which the Lenders have made certain credit and
other financial accommodations available to and on behalf of the Borrower; and

WHEREAS, the Borrower has requested that the Administrative Agent and the
Majority Lenders amend certain provisions of the Credit Agreement, and the
Administrative Agent and the Majority Lenders are willing to do so on the terms
and subject to the conditions set forth herein;

NOW, THEREFORE, to induce the Administrative Agent and the Majority Lenders to
enter into this Second Amendment, and in consideration of the premises and the
mutual covenants herein contained, for good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

Section 1. Defined Terms. Each capitalized term used herein but not otherwise
defined herein has the meaning given such term in the Credit Agreement, as
amended by this Second Amendment. Unless otherwise indicated, all section
references in this Second Amendment refer to sections of the Credit Agreement.

Section 2. Amendments to Credit Agreement.

2.1 Amendments to Section 1.02.

(a) Section 1.02 is hereby amended by deleting the defined terms “Agreement”,
“Existing 2018 Notes”, “Existing 2018 Notes Indenture”, “Permitted Additional
Senior Notes” and “Senior Notes” and replacing them with the following:

“‘Agreement’ means this Credit Agreement, as amended by that certain First
Amendment dated as of March 26, 2012 and that Second Amendment dated as of
September 4, 2012, as the same may from time to time be further amended,
modified, supplemented or restated.

‘Existing 2018 Notes’ means the Borrower’s 8.625% Senior Notes due 2018 issued
on November 2, 2010 pursuant to the Existing 2018 Notes Indenture, the aggregate
outstanding principal amount of which as of the Effective Date is $400,000,000.

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‘Existing 2018 Notes Indenture’ means that certain Indenture dated as of May 28,
2008 among the Borrower, certain Subsidiaries of the Borrower and Wells Fargo
Bank, National Association, as trustee, as supplemented by the Fourth
Supplemental Indenture dated as of November 2, 2010, the Sixth Supplemental
Indenture dated as of May 4, 2011, the Eighth Supplemental Indenture dated as of
August 5, 2011 and the Officer’s Certificate dated as of November 17, 2011, and
as the same may be amended, restated, modified or further supplemented from time
to time (to the extent such amendment, restatement, modification or supplement
is applicable to the Existing 2018 Notes or the Additional 2018 Notes) in
accordance with the terms of this Agreement.

‘Permitted Additional Senior Notes’ means any unsecured senior, senior
subordinated or convertible notes issued after the Second Amendment Effective
Date by the Borrower under Section 9.02(f).

‘Senior Notes’ means the Existing Senior Notes, the Additional 2018 Notes, any
Permitted Additional Senior Notes and any Permitted Refinancing Debt in respect
thereof.”

(b) Section 1.02 is hereby amended by adding the following defined terms thereto
in the appropriate alphabetical order:

“‘Additional 2018 Notes’ means the Borrower’s 8.625% Senior Notes due 2018,
issued on November 17, 2011 pursuant to the Existing 2018 Notes Indenture, the
aggregate outstanding principal amount of which as of the Second Amendment
Effective Date is $200,000,000.

‘Second Amendment Effective Date’ means September 4, 2012.”

2.2 Amendments to Section 9.02.

(a) Section 9.02(f) is hereby amended by deleting the reference to
“$400,000,000” and replacing it with “$350,000,000”.

(b) Section 9.02 is hereby amended by adding a new clause (k) thereto reading in
its entirety as follows:

“(k) the Additional 2018 Notes and any Permitted Refinancing Debt in respect
thereof.”

Section 3. Conditions Precedent. This Second Amendment shall become effective on
the date when each of the following conditions is satisfied (or waived in
accordance with Section 12.02) (such date, the “Second Amendment Effective
Date”):

3.1 The Administrative Agent shall have received all fees and other amounts due
and payable on or prior to the Second Amendment Effective Date, including, to
the extent invoiced, reimbursement or payment of all out-of-pocket expenses
required to be reimbursed or paid by the Borrower under the Credit Agreement.

 

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3.2 The Administrative Agent shall have received from the Majority Lenders and
the Borrower, counterparts (in such number as may be requested by the
Administrative Agent) of this Second Amendment signed on behalf of such Person.

3.3 No Default shall have occurred and be continuing as of the date hereof,
after giving effect to the terms of this Second Amendment.

3.4 The Administrative Agent shall have received such other documents as the
Administrative Agent or its special counsel may reasonably require in connection
with the transactions contemplated hereby.

The Administrative Agent is hereby authorized and directed to declare this
Second Amendment to be effective when it has received documents confirming or
certifying, to the satisfaction of the Administrative Agent, compliance with the
conditions set forth in this Section 3 or the waiver of such conditions as
permitted in Section 12.02 of the Credit Agreement. Such declaration shall be
final, conclusive and binding upon all parties to the Credit Agreement for all
purposes.

Section 4. Miscellaneous.

4.1 Confirmation. The provisions of the Credit Agreement, as amended by this
Second Amendment, shall remain in full force and effect following the
effectiveness of this Second Amendment.

4.2 Ratification and Affirmation; Representations and Warranties. The Borrower
hereby (a) acknowledges the terms of this Second Amendment; (b) ratifies and
affirms its obligations under, and acknowledges its continued liability under,
each Loan Document to which it is a party and agrees that each Loan Document to
which it is a party remains in full force and effect as expressly amended hereby
and (c) represents and warrants to the Lenders that as of the date hereof, after
giving effect to the terms of this Second Amendment:

(i) all of the representations and warranties of the Borrower and the Guarantors
contained in the Loan Documents are true and correct in all material respects,
except to the extent any such representations and warranties are expressly
limited to an earlier date, in which case, such representations and warranties
shall continue to be true and correct in all material respects as of such
specified earlier date, and

(ii) no Default or Event of Default has occurred and is continuing.

4.3 Loan Document. This Second Amendment is a Loan Document.

4.4 Counterparts. This Second Amendment may be executed by one or more of the
parties hereto in any number of separate counterparts, and all of such
counterparts taken together shall be deemed to constitute one and the same
instrument. Delivery of this Second Amendment by facsimile transmission shall be
effective as delivery of a manually executed counterpart hereof.

 

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4.5 NO ORAL AGREEMENT. THIS SECOND AMENDMENT, THE CREDIT AGREEMENT AND THE OTHER
LOAN DOCUMENTS EXECUTED IN CONNECTION HEREWITH AND THEREWITH REPRESENT THE FINAL
AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS, OR UNWRITTEN ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO
SUBSEQUENT ORAL AGREEMENTS BETWEEN THE PARTIES.

4.6 GOVERNING LAW. THIS SECOND AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF TEXAS.

4.7 Payment of Expenses. In accordance with Section 12.03, the Borrower agrees
to pay or reimburse the Administrative Agent for all of its reasonable out-of-
pocket costs and reasonable expenses incurred in connection with this Second
Amendment, any other documents prepared in connection herewith and the
transactions contemplated hereby, including, without limitation, the reasonable
fees and disbursements of counsel to the Administrative Agent.

4.8 Severability. Any provision of this Second Amendment which is prohibited or
unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective
to the extent of such prohibition or unenforceability without invalidating the
remaining provisions hereof, and any such prohibition or unenforceability in any
jurisdiction shall not invalidate or render unenforceable such provision in any
other jurisdiction.

4.9 Successors and Assigns. This Agreement shall be binding upon and inure to
the benefit of the parties hereto and their respective successors and assigns.

[SIGNATURES BEGIN NEXT PAGE]

 

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IN WITNESS WHEREOF, the parties hereto have caused this Second Amendment to be
duly executed as of the date first written above.

 

BORROWER:    

CARRIZO OIL & GAS, INC.

    By:   /s/ Paul F. Boling       Paul F. Boling Chief Financial Officer,      
Vice President, Secretary and Treasurer

 

Signature Page to Second Amendment

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LENDERS:     WELLS FARGO BANK, NATIONAL     ASSOCIATION, as Administrative Agent
    and a Lender     By:   /s/ Greg Smothers      

 

    Name:   Greg Smothers     Title:   Director

 

Signature Page to Second Amendment

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CREDIT AGRICOLE CORPORATE AND INVESTMENT BANK, as a Lender By:   /s/ Tom
Byargeon  

 

Name:   Tom Byargeon Title:   Managing Director By:   /s/ Sharada Manne  

 

Name:   Sharada Manne Title:   Managing Director

 

Signature Page to Second Amendment

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ROYAL BANK OF CANADA, as a Lender By:  

/s/ Mark Lumpkin, Jr.

Name:   Mark Lumpkin, Jr. Title:   Authorized Signatory

 

Signature Page to Second Amendment

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CAPITAL ONE, N.A., as a Lender By:  

/s/ Robert James

Name:   Robert James Title:   Vice President

 

Signature Page to Second Amendment

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COMPASS BANK, as a Lender By:  

/s/ Ann Van Wagener

Name:   Ann Van Wagener Title:   Vice President

 

Signature Page to Second Amendment

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UNION BANK, N.A., as a Lender

 

By:   /s/ Damien G. Meiburger Name:   Damien G. Meiburger Title:   Senior Vice
President

 

Signature Page to Second Amendment

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SOCIETE GENERALE, as a Lender By:   /s/ Graeme Bullen Name:   Graeme Bullen
Title:   Managing Director

 

Signature Page to Second Amendment

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CREDIT SUISSE AG, CAYMAN

ISLANDS BRANCH, as a Lender

By:   /s/ Ari Bruger Name:   Ari Bruger Title:   Vice President By:   /s/
Michael Spaight Name:   Michael Spaight Title:   Associate

 

Signature Page to Second Amendment