EXHIBIT 10.23

THIRD AMENDMENT TO THIRD AMENDED AND RESTATED CREDIT AGREEMENT

This Third Amendment to Third Amended and Restated Credit Agreement (this “Third
Amendment”) is entered into as of the 30th day of March, 2010 (the “Effective
Date”), by and among GEOMET, INC., a Delaware corporation (“Borrower”), BANK OF
AMERICA, N.A., as Administrative Agent (“Administrative Agent”), and the Banks
party hereto.

W I T N E S S E T H:

WHEREAS, Borrower, Administrative Agent, the financial institutions party
thereto as Banks, and the other agents party thereto are parties to that certain
Third Amended and Restated Credit Agreement dated as of June 9, 2006 (as
amended, the “Credit Agreement”) (unless otherwise defined herein, all terms
used herein with their initial letter capitalized shall have the meaning given
such terms in the Credit Agreement); and

WHEREAS, pursuant to the Credit Agreement, Banks have made a revolving credit
loan to Borrower and provided certain other credit accommodations to Borrower;
and

WHEREAS, Borrower has requested (a) a four month extension of the maturity date
under the Credit Agreement, (b) that the Borrowing Base be reduced to
$123,000,000, and (c) that the minimum current ratio covenant test for the
Fiscal Quarter ended March 31, 2010 be amended; and

WHEREAS, the Administrative Agent and the Banks are willing to amend the Credit
Agreement as set forth herein on the terms and conditions set forth herein.

NOW THEREFORE, for and in consideration of the mutual covenants and agreements
herein contained and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged and confessed, Borrower,
Administrative Agent and

Banks hereby agree as follows:

Section 1. Amendments. In reliance on the representations, warranties, covenants
and agreements contained in this Third Amendment, the Credit Agreement shall be
amended effective as of the Effective Date in the manner provided in this
Section 1.

1.1 Additional Definitions. Section 1.1 of the Credit Agreement is hereby
amended to add thereto in alphabetical order the following definitions which
shall read in full as follows:

“Third Amendment” means that certain Third Amendment to Third Amended and
Restated Credit Agreement dated as of March 30, 2010 among Borrower,
Administrative Agent and the Banks party thereto.

1.2 Amendments to Definitions. The definitions of “Applicable Margin”, “Letter
of Credit Fee”, “Loan Papers”, “Scheduled Determination Date” and “Termination
Date” contained in Section 1.1 of the Credit Agreement are hereby amended to
read in full as follows:

“Applicable Margin” means, on any date, 2.625% with respect to each Adjusted
Base Rate Tranche, and 3.50% with respect to each Eurodollar Tranche.

“Letter of Credit Fee” means, with respect to any Letter of Credit issued
hereunder, a fee in an amount equal to 3.50% of the average daily aggregate
amount of Letter of Credit Exposure of all Banks during the Fiscal Quarter (or
portion thereof) ending on the date such payment is due (calculated on a per
annum basis based on such average daily aggregate Letter of Credit Exposure).
Such fee shall be payable in accordance with the terms of Section 2.13.

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“Loan Papers” means this Agreement, the First Amendment, the Second Amendment,
the Third Amendment, the Notes, each Facility Guaranty now or hereafter
executed, the Mortgages, each Borrower Pledge Agreement now or hereafter
executed, each Subsidiary Pledge Agreement now or hereafter executed, the
Certificate of Effectiveness, the Letters of Credit and all other certificates,
documents or instruments delivered in connection with this Agreement, as the
foregoing may be amended from time to time.

“Scheduled Determination Date” means June 15, 2010, each June 30 (other than
June 30, 2010) and December 31, commencing June 30, 2006.

“Termination Date” means May 6, 2011.

1.3 Amendment to Minimum Current Ratio Provision. Clause (a) of Article X of the
Credit Agreement is hereby amended and restated in its entirety as follows:

(a) Borrower will not permit its ratio of Consolidated Current Assets to its
Consolidated Current Liabilities as of (i) the end of any Fiscal Quarter (other
than the Fiscal Quarter ended on March 31, 2010) to be less than 1 to 1 and
(ii) March 31, 2010 to be less than 0.80 to 1.

Section 2. Borrowing Base. In reliance on the representations, warranties,
covenants and agreements contained in this Third Amendment and pursuant to
Borrower’s request, the Borrowing Base shall be decreased, effective as of the
Effective Date, to $123,000,000 and shall remain at $123,000,000 until the next
Determination. Borrower and Banks agree (a) not to call for a Determination of
the Borrowing Base prior to June 15, 2010, (b) that the reduction of the
Borrower Base in this Section 2 (i) was at Borrower’s request, (ii) shall not be
deemed to be the determination of the Borrowing Base scheduled for June 15, 2010
(or such date promptly thereafter as reasonably possible for the Banks) pursuant
to Section 4.2 of the Credit Agreement and (iii) shall not be construed or
deemed to be a Special Determination for purposes of Section 4.3 of the Credit
Agreement.

Section 3. Conditions Precedent to Amendment. This Amendment shall be effective
as of the Effective Date when the following conditions precedent have been
satisfied:

3.1 Amendment/Consent. Administrative Agent shall have received counterparts of
this Amendment executed on behalf of Borrower, Administrative Agent and each
Bank, and of the consent attached to this Amendment executed by GeoMet Operating
and each Domestic Subsidiary party to a Facility Guaranty.

3.2 Fees. Borrower shall have paid to Administrative Agent, for the benefit of
each Bank in accordance with each Bank’s Commitment Percentage of the Borrowing
Base, a nonrefundable amendment fee equal to 0.25% of the Borrowing Base.

3.3 Opinion of Counsel. The Administrative Agent shall have received executed
legal opinions from Thompson & Knight L.L.P. and such other counsels to the
Credit Parties as the Administrative Agent shall reasonably request with respect
to this Amendment, such legal opinion to be in form and substance reasonably
satisfactory to the Administrative Agent.

3.4 Certificate of Borrower; Guarantors. Borrower shall have delivered to
Administrative Agent such certificates of authorized officers of Borrower and
the parties to the Facility Guarantees, certificates of Governmental
Authorities, certified copies of the certificates of incorporation, formation,
bylaws and operating agreements, as applicable, of Borrower and such guarantors
(or certified confirmation that no amendments, modifications or revisions have
been to those previously certifies and delivered to Administrative Agent, as
applicable), certified copies of resolutions of the directors, managers or
members, as applicable of Borrower and such guarantors and such other documents,
instruments and agreements as Administrative Agent shall require to evidence the
valid corporate existence and authority to conduct business of Borrower and such
guarantors and the due authorization, execution and delivery of this Third
Amendment any other documents related to this Third Amendment and any other
legal matters relating to Borrower, such guarantors, or the other Loan Papers,
all in a form and substance reasonable satisfactory to Administrative Agent and
its counsel.

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3.5 Commitments from NGP/North Shore. Administrative Agent shall have received
executed commitment letters, in form and substance reasonably acceptable to
Administrative Agent, from NGP Capital Resources Company, a Maryland
corporation, or one of its Affiliates reasonably acceptable to Administrative
Agent (“NGP”), and North Shore Energy, L.L.C. or one of its Affiliates
reasonably acceptable to Administrative Agent (“North Shore”), pursuant to which
NPG and North Shore have committed to purchase up to $40,000,000 of preferred
equity interests of Borrower on terms and conditions acceptable to
Administrative Agent, which commitment letters shall be certified by Borrower as
being true and correct copies in full force and effect on and as of the
Effective Date.

Section 4. Representations and Warranties of Borrower. To induce Banks and
Administrative Agent to enter into this Third Amendment, Borrower hereby
represents and warrants to Banks and Administrative Agent as follows:

4.1 Reaffirm Existing Representations and Warranties. Each representation and
warranty of Borrower contained in the Credit Agreement and the other Loan Papers
is true and correct on the date hereof and will be true and correct after giving
effect to the amendments set forth in Section 1 hereof.

4.2 Due Authorization; No Conflict. The execution, delivery and performance by
Borrower of this Third Amendment are within Borrower’s corporate powers, have
been duly authorized by all necessary action, require no action by or in respect
of, or filing with, any governmental body, agency or official and do not violate
or constitute a default under any provision of applicable law or any Material
Agreement binding upon Borrower or any other Credit Party, or result in the
creation or imposition of any Lien upon any of the assets of Borrower or any
other Credit Party except Permitted Encumbrances.

4.3 Validity and Enforceability. This Third Amendment constitutes the valid and
binding obligation of Borrower enforceable in accordance with its terms, except
as (a) the enforceability thereof may be limited by bankruptcy, insolvency or
similar laws affecting creditor’s rights generally, and (b) the availability of
equitable remedies may be limited by equitable principles of general
application.

4.4 No Default. No Default or Event of Default shall have occurred which is
continuing.

Section 5. Miscellaneous.

5.1 Reaffirmation of Loan Papers. Any and all of the terms and provisions of the
Credit Agreement and the Loan Papers shall, except as amended and modified
hereby, remain in full force and effect. The amendments contemplated hereby
shall not limit or impair any Liens securing the Obligations, each of which are
hereby ratified, affirmed and extended to secure the Obligations as they may be
increased pursuant hereto.

5.2 Parties in Interest. All of the terms and provisions of this Third Amendment
shall bind and inure to the benefit of the parties hereto and their respective
successors and assigns.

5.3 Legal Expenses. Borrower hereby agrees to pay on demand all reasonable fees
and expenses of counsel to Administrative Agent incurred by Administrative Agent
in connection with the preparation, negotiation and execution of this Third
Amendment and all related documents.

5.4 Counterparts. This Third Amendment may be executed in counterparts, and all
parties need not execute the same counterpart; however, no party shall be bound
by this Third Amendment until Borrower and all Banks have executed a
counterpart. Facsimiles or other electronic transmissions (e.g., pdf) shall be
effective as originals.

5.5 Complete Agreement. THIS THIRD AMENDMENT, THE CREDIT AGREEMENT AND THE OTHER
LOAN PAPERS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR ORAL AGREEMENTS OF THE
PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN OR AMONG THE PARTIES.

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5.6 Headings. The headings, captions and arrangements used in this Third
Amendment are, unless specified otherwise, for convenience only and shall not be
deemed to limit, amplify or modify the terms of this Third Amendment, nor affect
the meaning thereof.

5.7 Governing Law. This Third Amendment shall be governed by, and construed in
accordance with, the laws of the State of New York, other than conflict of laws
rules thereof.

IN WITNESS WHEREOF, the parties hereto have caused this Third Amendment to be
duly executed by their respective authorized officers on the date and year first
above written.

 

BORROWER:

GEOMET, INC.,

a Delaware corporation

By:    /s/ J. Darby Seré Name:    J. Darby Seré Title:   President & CEO

 

ADMINISTRATIVE AGENT/BANK:

BANK OF AMERICA, N.A.,

as Administrative Agent

By:    /s/ Jeffrey H. Rathkamp   Jeffrey H. Rathkamp,   Managing Director

 

BANK OF AMERICA, N.A.,

as a Bank

By:    /s/ Jeffrey H. Rathkamp   Jeffrey H. Rathkamp,   Managing Director

 

BANKS: BNP PARIBAS By:   /s/ Edward Pak Name:    Edward Pak Title:   Vice
President By:   /s/ Betsy Jocher Name:    Betsy Jocher Title:   Director

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BANK OF SCOTLAND plc By:   /s/ Julia R. Franklin Name:    Julia R. Franklin
Title:   Assistant Vice-President

 

U.S. BANK NATIONAL ASSOCIATION By:   /s/ Monte E. Deckerd Name:    Monte E.
Deckerd Title:   Senior Vice President

 

STERLING BANK By:   /s/ David Phillips Name:    David Phillips Title:   Senior
Vice President

The undersigned (i) consents and agrees to this Third Amendment, and (ii) agrees
that the Loan Papers to which it is a party (including, without limitation, the
Facility Guaranty dated as of June 9, 2006 or January 1, 2007, as applicable)
shall remain in full force and effect and shall continue to be the legal, valid
and binding obligation of the undersigned, enforceable against it in accordance
with its terms.

 

CONSENTED, ACKNOWLEDGED AND AGREED TO BY:

GEOMET GATHERING COMPANY, LLC,

an Alabama limited liability company

By:   /s/ J. Darby Seré Name:    J. Darby Seré Title:   President & CEO

 

GEOMET OPERATING COMPANY, INC.,

an Alabama corporation

By:   /s/ J. Darby Seré Name:    J. Darby Seré Title:   President & CEO