Exhibit 10.53

EXECUTION COPY

AGREEMENT

For

ENGINEERING, PROCUREMENT, AND

CONSTRUCTION SERVICES

for

42 - INCH SABINE PASS PIPELINE PROJECT

between

CHENIERE SABINE PASS PIPELINE COMPANY

and

WILLBROS ENGINEERS, INC.

AGREEMENT

THIS AGREEMENT for Engineering, Procurement and Construction Services (the “Agreement”) is made and entered into effective as of this 1st day of February 2006 (“Effective Date”) by and between Cheniere Sabine Pass Pipeline Company, a company organized under the laws of the State of Delaware (“Cheniere”), and Willbros Engineers, Inc., a company incorporated under the laws of the State of Delaware (“Willbros”). Cheniere and Willbros are hereinafter sometimes referred to individually as a “Party” or collectively as the “Parties.”

WHEREAS, Cheniere desires to design, build, own and operate the 16.0-mile, 42-inch pipeline and related facilities to be constructed from the Cheniere liquefied natural gas terminal to a pipeline interconnect at Johnson’s Bayou, all located entirely in Cameron Parish, Louisiana (as more fully described herein, the “Project”); and

WHEREAS, Willbros, itself or through its Subcontractors or Vendors desires to provide engineering, procurement and construction services related to the Project;

NOW, THEREFORE, in consideration of the mutual covenants herein and for other good and valuable consideration, the receipt and sufficiency of which are acknowledged, Cheniere and Willbros hereby agree as follows:

1. SCOPE OF WORK

2. PROJECT SCHEDULE

The Work shall be performed in accordance with the dates set forth in the Project Schedule attached as Schedule “F”.

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3. COMPENSATION

Willbros will submit invoices, and Cheniere shall pay Willbros the amounts due in accordance with Paragraph 5.4 of Schedule “A”. The sum of the Cost of the Work, the Willbros Management Fee and the Contingency Costs is guaranteed by Willbros not to exceed Sixty-Seven Million Six Hundred Seventy Thousand Two Hundred Dollars ($67,670,200), subject to additions and deductions by Change Order as provided herein (the “Guaranteed Maximum Price”), excluding Louisiana sales and use taxes applicable to permanent materials and equipment to be incorporated into the Project, which shall be reimbursed by Cheniere in accordance with Paragraph 5.4.2 of Schedule “A”. Costs which would cause the Guaranteed Maximum Price to be exceeded shall be paid by Willbros without reimbursement by Cheniere.

4. GENERAL

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Willbros or Cheniere may notify the other at any time of a change in, or addition to, the addresses and/or persons to which communications should be sent. Notices, demands, offers or other written instruments shall be deemed to have been duly given on the date actually received by its intended recipient.

IN WITNESS WHEREOF, Cheniere and Willbros have executed duplicate originals of the Agreement, effective and binding as of the Effective Date.

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SCHEDULE “A”

TERMS AND CONDITIONS

TABLE OF CONTENTS

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SCHEDULE “A”

TERMS AND CONDITIONS

1. DEFINITIONS

The following terms shall have the meanings indicated for all purposes of the Agreement and the use of the singular includes the plural, and vice versa:

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2. WILLBROS’ OBLIGATIONS

Subject to Paragraph 5 and in close cooperation and coordination with Cheniere, and subject to the terms and conditions of the Agreement, Willbros shall perform the Work in accordance with good engineering and construction practices, Applicable Law, Applicable Codes and Standards, the Specifications and all other provisions of this Agreement. Willbros accepts the relationship of trust and confidence established by this Agreement and covenants with Cheniere to exercise its skill and judgment in furthering the interests of Cheniere. Without limiting the generality of the foregoing or the requirements of any other provisions of this Agreement, Willbros shall:

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3. WILLBROS PERSONNEL AND EQUIPMENT

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4. WORK SITE RESPONSIBILITIES

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5. CHENIERE’S OBLIGATIONS

In close cooperation and coordination with Willbros, and subject to the terms and conditions of the Agreement, Cheniere shall:

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6. WORK PLAN AND REPORTS

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7. INSPECTION AND TESTING

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8. COMPLETION AND START-UP

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9. CHANGES

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10. INDEMNITY, LIENS AND PATENTS

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11. INSURANCE

Workers’ compensation with appropriate longshoremen’s or harbor workers’ endorsement (if applicable) covering all Willbros Personnel in accordance with the statutory requirements of the state of hire or country in which the Work is to be performed, and if the Work includes the use of vessels, appropriate maritime extensions. Employers’ liability insurance with the limit of One Million United States Dollars (U.S. $l,000,000) per accident or illness.

Commercial general liability insurance with contractual liability, products and completed operations, and broad form property damage coverage included, which shall provide for a combined single limit of One Million United States Dollars (U.S. $1,000,000) for personal injury, death or property damage resulting from each occurrence and covering all of Willbros’ Work under the Agreement; provided, however, this coverage requirement may be satisfied by Willbros through any combination of primary and excess liability insurance.

Automobile liability insurance covering owned, non-owned and hired motor vehicles, with combined single limits of at least One Million United States Dollars (U.S. $1,000,000) for personal injury, death, or property damage resulting from each occurrence.

Aircraft liability insurance, to the extent applicable, covering owned, non-owned and hired aircraft with a combined single limit of Five Million United States Dollars (U.S. $5,000,000) for bodily injury, death and property damage resulting from each occurrence.

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“All Risk” Insurance covering the full replacement cost of all supplies, equipment and materials to be incorporated into the Work while in the course of transit, including the land portion of any ocean or air shipments, and until arrival at the final local Work Sites. Such transit insurance shall include coverage against the perils of war, strikes, riots and civil commotion and shall insure all general average and salvage charges for which named insureds are responsible. Such insurance shall have a deductible of Fifty Thousand United States Dollars (U.S. $50,000) per loss.

Completed value form builder’s risk property insurance (subject to a deductible per loss not to exceed $50,000) upon the entire Work for one hundred percent (100%) of the full replacement cost value thereof (100% includes additional costs of engineering services in the event of a loss). This policy shall include the interests of Cheniere Group and Willbros Group in the Work as named insureds, as their interests may appear, shall name Cheniere as the loss payee, and shall be on an “All Risk” basis for physical loss or damage including fire, flood, earthquake, subsidence, hail, theft, vandalism and malicious mischief and shall include coverage for portions of the Work while it is stored off the Work Site or is in transit (except as otherwise covered by Paragraph 11.1.5). This policy shall provide, by endorsement or otherwise, that Willbros shall be solely responsible for the payment of all premiums under the policy, and that the Cheniere Group shall have no obligation for the payment thereof, notwithstanding that the Cheniere Group are named insureds under the policy. Willbros shall be responsible for any loss within the deductible of the policy for the liabilities assumed by Willbros hereunder.

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Errors and Omissions Professional Liability Insurance (“E&O Insurance”) having minimum limits of Five Million United States Dollars (U.S.$5,000,000) per claim and in the aggregate, with a deductible not in excess of Two Hundred Fifty Thousand United States Dollars (U.S.$250,000) per claim and in the aggregate, on a claims made basis. E&O Insurance shall cover liability arising out of or based upon any negligent design, engineering or other professional services performed by Willbros or any of its Subcontractors which is required as or associated with any part of the Work. The E&O Insurance shall have a retroactive date prior to the performance of any Work to be provided under this Agreement, shall have a policy period or renewal period extending through the termination or expiration of this Agreement and for two (2) years thereafter, and shall state that in the event of cancellation or non-renewal, the discovery period for insurance claims (tail coverage) shall be at least thirty-six (36) months.

Umbrella or excess liability insurance, written on a “following form” basis and providing coverage in excess of the coverages required to be provided by Willbros for employer’s liability insurance, commercial general liability insurance and automobile liability insurance, with limits of Twenty-Five Million United States Dollars (U.S.$25,000,000) combined single limit each claim and in the aggregate.

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12. WARRANTY

Willbros and its Subcontractors and Vendors shall exercise that high degree of skill and judgment normally exercised by firms performing services of a similar nature.

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13. TITLE TO THE WORK AND TO WORK PRODUCT,

CONFIDENTIAL INFORMATION

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14. DISPUTE RESOLUTION

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The Parties acknowledge that Cheniere will be prejudiced if Willbros fails to provide the notice required under this Paragraph 14.1, and agree that such requirement is an express condition precedent necessary to any right for an adjustment in the Guaranteed Maximum Price, the Project Schedule, any Work or any other modification to any other obligation of Willbros under this Agreement. Oral notice, shortness of time, or Cheniere’s actual knowledge of a particular circumstance shall not waive, satisfy, discharge or otherwise excuse Willbros’ strict compliance with this Paragraph 14.1.

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15. SUSPENSION OF WORK

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16. TERMINATION AT CHENIERE’S CONVENIENCE

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Willbros shall submit all reasonable direct close-out costs to Cheniere for verification and audit within sixty (60) days following the effective date of termination.

17. TERMINATION BY CHENIERE FOR CAUSE

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18. TERMINATION BY WILLBROS

Should Cheniere fail to pay Willbros undisputed invoiced amounts when due under this Agreement, Willbros may demand in writing that Cheniere comply with the payment terms of this Agreement. If, within forty-five (45) days after Cheniere’s receipt of such a demand, Cheniere has not taken satisfactory steps to cure such failure, Willbros may, without prejudice to the exercise of any other rights or remedies which may be available to it, terminate this Agreement by giving Cheniere written notice to that effect. Such termination hereunder by Willbros shall be effective on the date specified in Willbros’ termination notice. In the event of termination under this Paragraph 18, Willbros have the rights (and Cheniere shall make the payments) provided for in Paragraph 16 in the event of a Cheniere termination for convenience. The right of Willbros to terminate this Agreement for cause shall be without prejudice to, and not in lieu of, any other remedies available to Willbros under this Agreement.

19. WILLBROS’ OBLIGATIONS UPON SUSPENSION OR TERMINATION

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20. FORCE MAJEURE AND CHENIERE-CAUSED DELAY

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21. LIQUIDATED DAMAGES

Provided, however, in no event shall such Liquidated Damages exceed the total sum of Five Hundred Sixty Thousand Dollars ($560,000), provided that such limitation of liability shall not be construed to limit Willbros’ other obligations or liabilities under this Agreement (including its obligations (i) to complete the Work for the compensation provided under this Agreement, (ii) to perform all Work required to achieve Start-up and Project Completion, and (iii) with respect to Warranties), nor shall such limitation of liability apply in the event of Willbros’ willful misconduct (including the willful refusal to perform the Work, willful delay in performing the Work or abandonment of the Work) or gross negligence.

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22. PUBLICITY RELEASES

Should Willbros or any of its Subcontractors or Vendors desire to publish or release any publicity or public relations materials of any kind relating to the Agreement specifically or the Project generally, Willbros shall first submit such material to Cheniere for review. Willbros shall not publish or release any such material without Cheniere’s prior consent, such consent not to be unreasonably withheld.

23. GOVERNING LAW

It is understood that the Agreement is governed by the laws of the State of Texas except to the extent its conflict of law principles would refer to the law of another jurisdiction, the Parties acknowledge that the laws of Louisiana govern the rights and obligations of the Parties as to the validity and enforcement of mechanics’ and materialmen’s liens. Only to the extent that either Party may seek relief of the courts pursuant to this Agreement, Cheniere and Willbros each hereby submit to the exclusive jurisdiction of the federal and state courts located in Houston, Texas, and agree that service of process may be affected upon them by delivery to the addresses given in the Signature Document.

24. GENERAL PROVISIONS

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END OF SCHEDULE “A”

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ATTACHMENT I

WILLBROS’ PARENT GUARANTEE

This GUARANTEE (this “Guarantee”) effective February 01, 2006, is made by Willbros USA, Inc. organized under the laws of the State of Delaware (“Guarantor”), in favor of Cheniere Sabine Pass Pipeline Company, a company organized under the laws of the State of Delaware (“Owner,” and, together with Guarantor, each a “Party” and, collectively, the “Parties”). Capitalized terms used, but not otherwise defined, herein shall have the respective meanings ascribed to such terms in the Agreement (as defined below).

RECITALS

WHEREAS, Owner has agreed to enter into the Agreement for the Engineering, Procurement and Construction of the 42-inch Sabine Pass Pipeline dated February 01, 2006, with Willbros Engineers, Inc. (“Willbros”) for the engineering, procurement, construction, commissioning, start-up and testing of the 42-inch Sabine Pass Pipeline Project (the “Project”) located in Cameron Parish, Louisiana and a letter agreement dated February 01, 2006, with Willbros (collectively, the “Agreement”), which are hereby incorporated by reference in this Guarantee and made a part hereof; and

WHEREAS, Willbros is a subsidiary of Guarantor; and

WHEREAS, it is a condition to Owner and Willbros’ entering into the Agreement that Guarantor execute and deliver this Guarantee.

NOW THEREFORE, in consideration of the promises and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Parties hereby agree as follows:

1. Guarantee.

(a) On the terms and subject to the conditions contained herein, Guarantor hereby unconditionally and irrevocably guarantees, to and for the benefit of Owner, the full and punctual performance and payment, as and when each such payment or performance becomes due (whether at the stated due date, by acceleration or otherwise), by or on behalf of Willbros of any and all obligations or amounts owed by Willbros to Owner in connection with and to the extent provided for in the Agreement (the “Guaranteed Obligations”). The Guaranteed Obligations of Guarantor hereunder are direct and primary obligations.

(b) This Guarantee is an unconditional, present, and continuing guarantee of performance and payment, and not of collection, is in no way conditioned or contingent upon any attempt to collect from or enforce performance or payment by Willbros or upon any other event, contingency or circumstance whatsoever, and shall remain in full force and effect and be binding upon and against Guarantor and its successors and permitted assigns (and shall inure to the benefit of Owner and its successors, endorsees, transferees, and permitted assigns), without

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regard to the validity or enforceability of the Agreement. If, for any reason, Willbros shall fail or be unable duly, punctually, and fully to perform or pay, as and when such performance or payment is due, any of the Guaranteed Obligations, Guarantor shall promptly perform or pay, or cause to be performed or paid, such Guaranteed Obligations.

(c) Guarantor agrees that any judgment from any litigation (or any award resulting from any arbitration, if Owner and Willbros should agree to arbitrate) between Willbros and Owner under the Agreement (whether in contested litigation or arbitration, by default or otherwise) shall be conclusive and binding on the Parties for the purposes of determining Guarantor’s obligations under the Guarantee.

(d) Guarantor further agrees to pay to Owner any and all costs, expenses (including, without limitation, all reasonable fees and disbursements of counsel), and damages which may be paid or incurred by Owner in enforcing any rights with respect to this Guarantee, including, without limitation, collecting against Guarantor under this Guarantee.

2. Obligations Unconditional, Continuing; Etc.

Guarantor agrees that the obligations of Guarantor set forth in this Guarantee shall be direct obligations of Guarantor, and such obligations shall be irrevocable and unconditional, shall not be subject to any counterclaim, set-off, deduction, diminution, abatement, recoupment, suspension, deferment, reduction or defense (other than full and strict compliance with its obligations hereunder) based upon any claim Guarantor or any other person may have against Owner or any other person and shall remain in full force and effect without regard to and shall not be released, discharged or in any way affected or impaired by, any circumstance or condition whatsoever (other than full and strict compliance by Guarantor with its obligations hereunder) (whether or not Guarantor shall have any knowledge or notice thereof), including, without limitation: (i) any amendment or modification of or supplement to or other change in the Agreement or any other document, including, without limitation, any change order, renewal, extension, acceleration or other changes to payment terms thereunder; (ii) any failure, omission or delay on the part of Owner or any other person to confirm or comply with any term of the Agreement, (iii) any waiver, consent, extension, indulgence, compromise, release or other action or inaction under or in respect of the Agreement or any other document or any obligation or liability of Owner or any other person, or any exercise or non-exercise of any right, remedy, power, or privilege under or in respect of any such instrument or agreement or any such obligation or liability, other than as expressly set forth in writing executed by Owner and Guarantor; (iv) any bankruptcy, insolvency, reorganization, arrangement, readjustment, liquidation, or similar proceeding with respect to Owner, Willbros or any other person or any of their respective properties, or any action taken by any trustee or receiver or by any court in any such proceeding; (v) any discharge, termination, cancellation, invalidity or unenforceability, in whole or in part, of the Agreement or any other document or any term or provision thereof; (vi) any merger or consolidation of Guarantor or Willbros into or with any other person or any sale, lease, or transfer of all or any of the assets of Guarantor or Willbros; (vii) any change in the ownership of Guarantor or Willbros; (viii) any winding up or dissolution of Willbros; or (ix) to the extent permitted under Applicable Law, any other occurrence or circumstance whatsoever, whether similar or dissimilar to the foregoing, which might otherwise constitute a legal or

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equitable defense or discharge of the liabilities of guarantor or surety or which might otherwise limit recourse against Guarantor. Guarantor reserves the right to (a) set-off against any payment that has become due and payable by the Owner to Willbros under the Agreement and (b) assert defenses which Willbros may have under or with respect to the Agreement to performance of any Guaranteed Obligations other than defenses arising from the bankruptcy or insolvency of Willbros or Willbros’ failure to have the authority to (x) execute or deliver the Agreement or (y) perform its obligations under the Agreement. The Guaranteed Obligations constitute the full recourse obligations of Guarantor enforceable against it to the full extent of all its assets and properties. Without limiting the generality of the foregoing, Guarantor agrees that repeated and successive demands may be made and recoveries may be had hereunder as and when, from time to time, Willbros shall fail to perform obligations or pay amounts owed by Willbros under the Agreement and that notwithstanding the recovery hereunder for or in respect of any given failure to so comply by Willbros under the Agreement, this Guarantee shall remain in full force and effect and shall apply to each and every subsequent such failure.

3. Reinstatement. Guarantor agrees that this Guarantee shall be automatically reinstated with respect to any payment made by or on behalf of Willbros pursuant to the Agreement if and to the extent that such payment is rescinded or must be otherwise restored, whether as a result of any proceedings in bankruptcy or reorganization or otherwise.

4. Waiver of Demands, Notices; Etc. Guarantor hereby unconditionally waives, to the extent permitted by Applicable Law: (i) notice of any of the matters referred to in Paragraph 2 hereof; (ii) all notices which may be required by Applicable Law, or otherwise, now or hereafter in effect, to preserve any rights against Guarantor hereunder, including, without limitation, any demand, proof, or notice of non-payment or non-performance of any Guaranteed Obligation; (iii) any right to the enforcement, assertion, or exercise of any right, remedy, power, or privilege under or in respect of the Agreement; (iv) notice of acceptance of this Guarantee, demand, protest, presentment, notice of failure of performance or payment, and any requirement of diligence; (v) any requirement to exhaust any remedies or to mitigate any damages resulting from failure of performance or payment by Willbros under the Agreement or by any other person under the terms of the Agreement; and (vi) any other circumstance whatsoever which might otherwise constitute a legal or equitable discharge, release, or defense of a guarantor or surety, or which might otherwise limit recourse against Guarantor.

5. No Subrogation. Notwithstanding any performance, payment or payments made by Guarantor hereunder (or any set-off or application of funds of Guarantor by Owner), Guarantor shall not be entitled to be subrogated to any of the rights of Willbros or of any rights of Owner hereunder, or any collateral, security, or guarantee or right of set-off held by Owner, for the performance or payment of the obligations guaranteed hereunder, nor shall Guarantor seek or be entitled to assert or enforce any right of contribution, reimbursement, indemnity or any other right to payment from Willbros as a result of Guarantor’s performance of its obligations pursuant to this Guarantee until all Guaranteed Obligations are performed or paid in full. If any amount shall be paid to Guarantor on account of such subrogation, contribution, reimbursement or indemnity rights at any time when all of the Guaranteed Obligations and all amounts owing hereunder shall not have been performed and paid in full, such amount shall be held by Guarantor in trust for Owner, segregated from other funds of Guarantor, and shall, forthwith

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upon receipt by Guarantor, be turned over to Owner in the exact form received by Guarantor (duly endorsed by Guarantor to Owner, if required), to be applied against the Guaranteed Obligations, whether or not matured, in such order as Owner may determine.

6. Representations and Warranties. Guarantor represents and warrants that:

(a) it is a corporation duly organized and validly existing under the laws of the State of Delaware and has the corporate power and authority to execute, deliver and carry out the terms and provisions of the Guarantee;

(b) the execution, delivery and performance of this Guarantee will not conflict with, violate or breach the terms of any agreement of Guarantor;

(c) no authorization, approval, consent or order of, or registration or filing with, any court or other governmental body having jurisdiction over Guarantor is required on the part of Guarantor for the execution and delivery of this Guarantee; and

(d) this Guarantee, when executed and delivered, will constitute a valid and legally binding agreement of Guarantor, except as the enforceability of this Guarantee may be limited by the effect of any applicable bankruptcy, insolvency, reorganization, moratorium or similar laws affecting creditors’ rights generally and by general principles of equity as they apply to the Guarantor.

7. Miscellaneous.

(a) This Guarantee shall inure to the benefit of and be binding upon the Parties hereto and their respective successors and permitted assigns. Guarantor may not assign or transfer this Guarantee or any rights or obligations hereunder without Owner’s prior written consent. Owner may assign this Guarantee, in whole or part, to any of its affiliates or co-venturers or to any person jointly controlled by Owner and any co-venturers. Furthermore, Owner may assign, pledge and/or grant a security interest in this Guarantee to any lender without Guarantor’s consent. Except as otherwise provided in this Paragraph 7, nothing herein, express or implied, is intended or shall be construed to confer upon or to give to any person other than the Parties hereto any rights, remedies, or other benefits.

(b) This Guarantee shall be governed by, and construed in accordance with, the laws of the state of Texas, without giving effect to the principles thereof relating to conflicts of law.

(c) The Parties agree that any claim, dispute, controversy, difference, disagreement, or grievance (of any and every kind or type, whether based on contract, tort, statute, regulation or otherwise) arising out of, connected with, or relating in any way to this Guarantee (including, without limitation, the construction, validity, interpretation, termination, enforceability or breach of this Guarantee, the relationship of the Parties established by this Guarantee, or any dispute over arbitrability or jurisdiction) (“Dispute”) shall be decided by final and binding arbitration. Any arbitration held under this Guarantee shall be held in Houston, Texas, unless otherwise agreed by the Parties, shall be administered by the Dallas, Texas office of the American Arbitration Association (“AAA”) and shall, except as otherwise modified by this Paragraph 7(c),

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be governed by the AAA’s Construction Industry Arbitration Rules and Mediation Procedures (including Procedures for Large, Complex Construction Disputes) (the “AAA Rules”). The number of arbitrators required for the arbitration hearing shall be determined in accordance with the AAA Rules. The arbitrator(s) shall determine the rights and obligations of the Parties according to the substantive law of the state of Texas, excluding its conflict of law principles, as would a court for the state of Texas; provided, however, the law applicable to the validity of the arbitration clause, the conduct of the arbitration, including resort to a court for provisional remedies, the enforcement of any award and any other question of arbitration law or procedure shall be the Federal Arbitration Act, 9 U.S.C.A. § 2. Issues concerning the arbitrability of a matter in dispute shall be decided by a court with proper jurisdiction. The Parties shall be entitled to engage in reasonable discovery, including the right to production of relevant and material documents by the opposing Party and the right to take depositions reasonably limited in number, time and place, provided that in no event shall any Party be entitled to refuse to produce relevant and non-privileged documents or copies thereof requested by the other Party within the time limit set and to the extent required by order of the arbitrator(s). All disputes regarding discovery shall be promptly resolved by the arbitrator(s). This agreement to arbitrate is binding upon the Parties and the successors and permitted assigns of any of them. At Owner’s sole option, any other person may be joined as an additional party to any arbitration conducted under this Paragraph 7(c), provided that the party to be joined is or may be liable to either Party in connection with all or any part of any Dispute between the Parties. The arbitration award shall be final and binding, in writing, signed by all arbitrators, and shall state the reasons upon which the award thereof is based. The Parties agree that judgment on the arbitration award may be entered by any court having jurisdiction thereof.

(d) No modification or amendment of this Guarantee shall be of any force or effect unless made in writing, signed by the Parties hereto, and specifying with particularity the nature and extent of such modification or amendment. This Guarantee constitutes the entire and only understanding and agreement among the Parties hereto with respect to the subject matter hereof and cancels and supersedes any prior negotiations, proposals, representations, understandings, commitments, communications, or agreements, whether oral or written, with respect to the subject matter hereof.

(e) All notices, requests and communications to a Party hereunder shall be in writing (including telecopy and/or fax or similar writing) and shall be sent:

If to Owner:

Graham A. McArthur

Vice President and Treasurer

Cheniere Sabine Pass Pipeline

717 Texas Avenue, Suite 3100

Houston, Texas 77002

Telephone: (713) 659-1361

Fax: (713) 659-5459

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If to Guarantor:

Gay S. Mayeux

Vice President and Assistant Treasurer

Willbros USA, Inc.

4400 Post Oak Parkway

Suite 1000

Houston, Texas 77027

Telephone: (713) 403-8147

Fax: (713) 403-8017

or to such other address or telecopy number and with such other copies, as such Party may hereafter reasonably specify by notice to the other Parties. Each such notice, request or communication shall be effective upon receipt, provided that if the day of receipt is not a business day then it shall be deemed to have been received on the next succeeding business day.

(f) The headings of the several provisions of this Guarantee are inserted for convenience only and shall not in any way affect the meaning or construction of any provision of this Guarantee.

(g) No forbearance or delay by Owner in asserting rights against Willbros shall affect or impair in any way Guarantor’s obligations hereunder or the rights of Owner hereunder.

(h) In addition to other assurances provided in this Guarantee, Guarantor acknowledges that Owner has obtained or may obtain project financing associated with the Project and Guarantor agrees to cooperate with Owner and its lenders in connection with such project financing, including, but not limited to, entering into direct agreements with lenders, as required by such lenders, covering matters that are customary in project financings of this type such as lender assignment or security rights with respect to this Guarantee, consent agreements, opinions of counsel, direct notices to lender and lender’s independent engineer, step-in/step-out rights, access by lenders’ representative, including lender’s independent engineer, and other matters applicable to such project financing.

(i) This Guarantee may be executed in any number of separate counterparts and all of said counterparts taken together shall be deemed to constitute one and the same instrument.

IN WITNESS WHEREOF, the undersigned have duly executed this Guarantee as of the date first above written.

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ATTACHMENT II - 1

PAYMENT BOND

Bond No.                    

KNOW ALL MEN BY THESE PRESENTS, that                      (hereinafter “Principal”) and                     , incorporated in the state of              and duly authorized to do business in Louisiana, (hereinafter “Surety”), are held and firmly bound unto Cheniere Sabine Pass Pipeline Company (hereinafter “Obligee”), and its representatives, successors and assigns, in the sum of                      Dollars ($            ) for the payment of which sum well and truly to be made the said Principal and Surety bind themselves, and their respective heirs, administrators, executors, successors and assigns jointly and severally, firmly by these presents.

WHEREAS, Principal has been awarded a contract with Obligee for the project known as the 42-inch Sabine Pass Pipeline Project in Cameron Parish, Louisiana (hereinafter called the “Contract”) and which Contract is hereby referred to and incorporated by express reference as if fully set forth herein.

NOW, THEREFORE, THE CONDITION OF THIS OBLIGATION IS SUCH, that if the Principal shall promptly make payment in full to all persons or entities supplying labor, material, services, utilities and equipment, or any other things in the prosecution of the work provided for in said Contract, and any and all modifications of said Contract that may hereafter be made, and shall indemnify and save harmless said Obligee of and from any and all loss, damage, and expense, including costs and attorneys’ fees, which the said Obligee may sustain by reason of Principal’s failure to do so, then this obligation shall be null and void; otherwise it shall remain in full force and effect.

The Surety agrees that no change, extension of time, alteration, addition, omission, waiver, or other modification of the terms of either the Contract or in the work to be performed, or in the specifications, or in the plans, or in the contract documents, or any forbearance on the part of either the Obligee or Principal to the other, shall in any way affect its obligation on this Bond, and Surety does hereby waive notice of any such changes, extensions of time, alterations, additions, omissions, waivers, or other modifications.

The Principal and the Surety agree that this Bond shall inure to the benefit of all persons or entities as supplying labor, material, services, utilities and equipment, or any other things in the prosecution of the work provided for in said Contract, as well as to the Obligee, and that any of such persons or entities may maintain independent actions upon this Bond in the name of the person or entities bringing any such action.

The parties executing this Bond on behalf of Principal and Surety represent and warrant that they are duly authorized to bind the Principal and Surety respectively.

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IN WITNESS WHEREOF, the above bounden parties have executed this instrument under their several seals this              day of                     , 200   the name and corporate seal of each corporate seal of each corporate party being hereto affixed and these presents duly signed by its undersigned representative, pursuant to authority of its governing body.

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ATTACHMENT II - 2

DUAL OBLIGEE RIDER FOR PAYMENT BOND

This Rider is to be attached to and forms a part of Payment Bond No.                      issued by                      (hereinafter referred to as “Surety”), as Surety, on the              day of                     , 20     (“Payment Bond”).

WHEREAS, on or about the              day of                 , 200  ,                      (hereinafter called the “Principal”), entered into a written agreement with (hereinafter called the “Primary Obligee”) for the construction of                      (hereinafter called the “Contract”); and

WHEREAS, the Principal and the Surety executed and delivered to said Primary Obligee the Performance Bond No.                  (“Performance Bond”) in connection with the Contract; and

WHEREAS, the Primary Obligee has requested the Principal and the Surety to execute and deliver this Dual Obligee Rider for Payment Bond and the Principal and the Surety have agreed to do so.

NOW, THEREFORE, the undersigned hereby agree and stipulate that Cheniere Sabine Pass Pipeline Company shall be a named obligee (hereinafter referred to as “Additional Obligee”) to the Payment Bond, subject to the conditions set forth below:

1. In the event of a material default in payment by the Primary Obligee to the Principal under the terms of the Contract, the right of the Additional Obligee to recover hereunder shall be subject to the condition that the Additional Obligee remedies said material payment default and thereafter continues to make payment to the Principal as required under the terms of the Contract.

2. The aggregate liability of the Surety under the Payment Bond, to any or all of the obligees (Primary and Additional Obligees), as their interests may appear, is limited to the total penal sum of the Payment Bond.

Signed, sealed and dated this             day of             , 20    .

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ATTACHMENT II - 3

PERFORMANCE BOND

Bond No.                                    

KNOW ALL MEN BY THESE PRESENTS, that                                      (hereinafter “Principal”) and                                     , incorporated in the state of                          and duly authorized to do business in Louisiana (hereinafter “Surety”), are held and firmly bound unto Cheniere Sabine Pass Pipeline Company (hereinafter “Obligee”), and its representatives, successors and assigns, in the sum of                  Dollars ($                ) for the payment of which sum well and truly to be made the said Principal and Surety bind themselves, and their respective heirs, administrators, executors, successors and assigns jointly and severally, firmly by these presents.

WHEREAS, Principal has been awarded a contract with Obligee for the project known as the 42-inch Sabine Pass Pipeline Project in Cameron Parish, Louisiana (hereinafter called the “Contract”) and which Contract is hereby referred to and incorporated by express reference as if fully set forth herein.

NOW, THEREFORE, THE CONDITION OF THIS OBLIGATION IS SUCH, that if the above bounden Principal shall well and truly perform all the work, undertakings, covenants, terms, conditions, and agreements of said Contract within the time provided therein and any extensions thereof that may be granted by Obligee, and during the life of any obligation, guaranty or warranty required under said Contract, and shall also well and truly perform all the undertakings, covenants, terms, conditions, and agreements of any and all modifications of said Contract that may hereafter be made, and shall indemnify and save harmless said Obligee of and from any and all loss, damage, and expense, including costs and attorneys’ fees, which the Obligee may sustain by reason of Principal’s failure to do so, then this obligation shall be null and void; otherwise it shall remain in full force and effect.

The Surety agrees that no change, extension of time, alteration, addition, omission, waiver, or other modification of the terms of either the Contract or in the work to be performed, or in the specifications, or in the plans, or in the contract documents, or any forbearance on the part of either the Obligee or Surety to the other, shall in any way affect said Surety’s obligation on this Bond, and said Surety does hereby waive notice of any such changes, extensions of time, alterations, additions, omissions, waivers, or other modifications. The parties executing this Bond on behalf of Principal and Surety represent and warrant that they are duly authorized to bind the Principal and Surety respectively.

IN WITNESS WHEREOF, the above bounden parties have executed this instrument under their several seals this                  day of                 , 200  , the name and corporate seal of each corporate seal of each corporate party being hereto affixed and these presents duly signed by its undersigned representative, pursuant to authority of its governing body.

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ATTACHMENT II - 4

DUAL OBLIGEE RIDER FOR PERFORMANCE BOND

This Rider is to be attached to and forms a part of Performance Bond No.                      issued by                      (hereinafter referred to as “Surety”), as Surety, on the              day of                     , 20     (“Performance Bond”).

WHEREAS, on or about the              day of                     , 200  ,                      (hereinafter called the “Principal”), entered into a written agreement with                                  (hereinafter called the “Primary Obligee”) for the construction of                      (hereinafter called the “Contract”); and

WHEREAS, the Principal and the Surety executed and delivered to said Primary Obligee the Payment Bond No.                      (“Payment Bond”) in connection with the Contract; and

WHEREAS, the Primary Obligee has requested the Principal and the Surety to execute and deliver this Dual Obligee Rider for Performance Bond and the Principal and the Surety have agreed to do so.

NOW, THEREFORE, the undersigned hereby agree and stipulate that Cheniere Sabine Pass Pipeline Company shall be a named obligee (hereinafter referred to as “Additional Obligee”) to the Performance Bond, subject to the conditions set forth below:

1. In the event of a material default in performance by the Primary Obligee to the Principal under the terms of the Contract, the right of the Additional Obligee to recover hereunder shall be subject to the condition that the Additional Obligee remedies said material performance default and thereafter continues to perform as required under the terms of the Contract.

2. The aggregate liability of the Surety under the Performance Bond, to any or all of the obligees (Primary and Additional Obligees), as their interests may appear, is limited to the total penal sum of the Performance Bond.

Signed, sealed and dated this              day of                     , 20    .

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ATTACHMENT III

MECHANICAL COMPLETION CERTIFICATE

Date:                    

Cheniere Sabine Pass Pipeline Company

717 Texas Avenue, Suite 3100

Houston, Texas 77002

Attention: Richard E. Keyser

Pursuant to Paragraph 8.1 of the Agreement, Willbros hereby certifies that it has completed all requirements under the Agreement for Mechanical Completion with respect to the Sabine Pass Pipeline Project (“Project”), including: (a) the Work is approved by Cheniere as being ready for pre-commissioning and/or commissioning; (b) Willbros has delivered to Cheniere a set of original test and inspection certificates, including hydrostatic test reports, materials documentation, MAOP establish records, and internal geometry pig results; (c) Willbros has completed all construction, procurement, fabrication, assembly, erection, installation and testing, including final pipeline hydrostatic tests for the pipeline and all appropriate appurtenances to ensure that such systems were correctly constructed, procured, fabricated, assembled, erected, installed and tested and are capable of being operated safely and reliably within the requirements contained in this Agreement; (d) Willbros hereby delivers this Mechanical Completion Certificate as required under Paragraph 8.1 of the Agreement; (e) Willbros has dewatered and dried the pipeline to a dewpoint of negative forty degrees Fahrenheit (-40ºF); (f) Willbros has completed all Exception Items in accordance with Paragraph 8.1 of the Agreement; and (g) Willbros has performed all other obligations required under the Agreement for Mechanical Completion.

Willbros certifies that it achieved all requirements under the Agreement for Mechanical Completion on                     , 200  .

Attached is all documentation required to be provided by Willbros under the Agreement to establish that Willbros has achieved all requirements under the Agreement for Mechanical Completion, including the required final pipeline hydrostatic test reports, materials documentation, MAOP establish records, and internal geometry pig results.

IN WITNESS WHEREOF, Willbros has caused this Mechanical Completion Certificate to be duly executed by its authorized representative and delivered as of the date first written above.

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ATTACHMENT IV

PROJECT COMPLETION CERTIFICATE

Date:                    

Cheniere Sabine Pass Pipeline Company

717 Texas Avenue, Suite 3100

Houston, Texas 77002

Attention: Richard E. Keyser

Pursuant to Paragraph 8.3 of the Agreement, Willbros hereby certifies that it has completed all requirements under the Agreement for Project Completion with respect to the Sabine Pass Pipeline Project (“Project”), including: (a) the successful achievement of Mechanical Completion of all systems for the Project; (b) the successful achievement of Start-up of all systems for the Project; (c) delivery by Willbros of all documentation required to be delivered under this Agreement, including any Work Product, Cheniere’s Confidential Information and other documentation; (d) delivery by Willbros to Cheniere of fully executed Final Lien and Claim Waivers in the form of Schedule “A”, Attachment X – Part 2 of the Agreement; (e) removal from the Work Site all of Willbros Personnel, supplies, waste, materials, rubbish and temporary facilities and restoration of the Work Site to its natural conditions in accordance with this Agreement, Applicable Law and Applicable Codes and Standards or any other requirements of any Governing Authority; (f) Willbros hereby delivers this Project Completion Certificate as required under Paragraph 8.3 of the Agreement; (g) delivery by Willbros to Cheniere of evidence acceptable to Cheniere that all Subcontractors and Vendors have been fully and finally paid, including fully executed Final Lien and Claim Waivers from all Subcontractors and Major Vendors in the form of Schedule “A”, Attachment X – Part 4 of the Agreement; (h) Willbros has completed all Exception Items in accordance with Paragraph 8.3 of the Agreement; and (i) performance of all other obligations required by the Agreement for Project Completion.

Attached is all documentation required to be provided by Willbros under the Agreement to establish that Willbros has achieved all requirements under the Agreement for Project Completion, including the required Willbros, Subcontractor, and Major Vendor Lien and Claim Waivers.

IN WITNESS WHEREOF, Willbros has caused this Project Completion Certificate to be duly executed by its authorized representative and delivered as of the date first written above.

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ATTACHMENT V

START-UP CERTIFICATE

Cheniere Sabine Pass Pipeline Company

717 Texas Avenue, Suite 3100

Houston, Texas 77002

Attention: Richard E. Keyser

Pursuant to Paragraph 8.2 of the Agreement, Willbros hereby certifies that it has completed all requirements under the Agreement for Start-up with respect to the Sabine Pass Pipeline Project (“Project”), including: (a) the successful achievement of Mechanical Completion of all systems for the Project; (b) Cheniere has purged the Project with either natural gas or nitrogen with assistance and support from Willbros as requested; (c) Willbros has completed all Exception Items in accordance with Paragraph 8.2 of the Agreement; and (d) performance of all other obligations required by the Agreement for Start-up.

Attached is all documentation required to be provided by Willbros under the Agreement to establish that Willbros has achieved all requirements under the Agreement for Start-up, including documentation evidencing the completion of all Exception Items required under Paragraph 8.2.

IN WITNESS WHEREOF, Willbros has caused this Start-up Certificate to be duly executed by its authorized representative and delivered as of the date first written above.

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ATTACHMENT VI

CHANGE ORDER FORM

The Agreement between the Parties listed above is changed as follows: (attach additional documentation if necessary)

Adjustment to price under the Agreement:

Adjustment to dates:

The Preparation and Material Receipt Commencement Date will be (increased)(decreased)(unchanged) by              (        ) calendar days and as a result of this Change Order is now:                     , 20    .

The Construction Commencement Date will be (increased)(decreased)(unchanged) by              (        ) calendar days and as a result of this Change Order is now:                     , 20    .

The Scheduled Mechanical Completion Date will be (increased)(decreased)(unchanged) by              (        ) calendar days and as a result of this Change Order is now:                     , 20    .

Other impacts to liability or obligation of Willbros or Cheniere under the Agreement:

Upon execution of this Change Order by Cheniere and Willbros, the above-referenced change shall become a valid and binding part of the original Agreement without exception or qualification, unless noted in this Change Order. Except as modified by this and any previously issued Change Orders, all other terms and conditions of the Agreement shall remain in full force and effect. This Change Order is executed by each of the Cheniere’s Authorized Representative and Willbros’ Authorized Representative.

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ATTACHMENT VII

APPROVED SUBCONTRACTORS AND VENDORS LIST

The following Subcontractors and Vendors each having subcontracts or purchase orders of any tier are approved Subcontractors and Vendors for the following portions of the Work:

Construction Subcontractors:

Geotechnical Investigation:

Cathodic Protection System Design:

Pipeline Civil Surveying:

Pipe Mills, DSAW:

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Pipe Mills, ERW:

Valves, Ball Mainline:

Valves, Control:

General Pipe, Valves and Fittings:

Bolts, Stud and Gaskets:

Fittings and Flanges (Hy Yield):

Bends, Induction:

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Pig Signal:

Launch/Receiver Package:

Regulator Package:

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ATTACHMENT VIII

ORGANIZATIONAL CHART

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ATTACHMENT IX

CHENIERE’S HEALTH, SAFETY AND ENVIRONMENTAL POLICIES

Health, safety and safeguarding of the environment are within Cheniere’s core values. Willbros shall take into consideration health, safety and the environment (“HSE”) throughout execution of the Work.

The minimum approach to the management of HSE issues is generally described in this Attachment IX, and Willbros shall comply with such minimum requirements and, to the extent possible, maintain the highest level of HSE stewardship for Work of this nature during the execution of the Work. At a minimum, the Work and Willbros’ HSE activities and plans shall comply with: (i) all Applicable Codes and Standards; (ii) all Applicable Laws, including 29 C.F.R. Part 1910, CERCLA, SARA, and all other applicable environmental laws, regulations and requirements; (iii) the FERC Certificate, and (iv) the most current FERC-authorized Wetland and Waterbody Construction and Mitigation Procedures and the Upland Erosion Control, Re-vegetation, and Maintenance Plan.

Cheniere’s general HSE policies shall apply to Willbros and its Subcontractors and Vendors performing Work at the Work Site, and shall apply to the fullest extent practical at all other sites where Work is being performed for Cheniere or where Cheniere personnel are involved.

Willbros shall pay the highest regard to safety and shall conform to all safety-related requirements set forth in the Agreement, including this Attachment IX and Schedule “D”.

Willbros shall be responsible for the safe performance of the Work under the Agreement, including: (i) the safety of all of the employees, agents, representatives and invitees of Willbros and its Subcontractors and Vendors engaged in the performance of the Work; (ii) ensuring that all Willbros Personnel are familiar with and will apply all applicable HSE rules and regulations; (iii) providing safety incident reports to Cheniere in accordance with the Agreement; (iv) providing a safe working environment at the Work Site; (v) the safe performance of the Work by all Willbros Personnel; and (vi) ensuring that awareness of the importance of safety is actively promoted at the Work Site.

Willbros shall pay the highest regard to protection of the environment and shall carry out environmental management to ensure that the Work is performed in an environmentally sound manner and in compliance with all provisions of the Agreement, including this Attachment IX, regarding the environment and Applicable Law.

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Willbros’ objective shall be to ensure, through the proper application of its environmental protection procedures, that the Work is: (i) managed, planned and engineered to minimize any impact upon the environment; (ii) performed and completed without incidents detrimental to the environment; and (iii) performed in full compliance with the environmental policy objectives.

Willbros shall incorporate all health, safety and environmental requirements of the Agreement, including this Attachment IX, into Willbros’ HSE plan which it shall implement and adhere to during the performance of the Work.

Willbros HSE plan shall contain a full description of the safety and environmental rules, procedures, guidelines, and Work instructions applicable at the Work Site, which Willbros shall use to ensure the safe and environmentally friendly management of the Work. The HSE plan shall cover all phases of the Work and all activities through Final Acceptance and shall specifically describe safety and environmental management at the Work Site.

The HSE plan shall address all safety and environmental matters relevant to the Work, including the following: (i) safety meetings and safety events; (ii) safety inspections; (iii) training schedule; (iv) safety reviews at the Work Site; (v) construction safety reviews; (vi) all reasonable emergency response plans, medical emergency plans; (vii) plans to control the possession and use of firearms, alcohol and controlled substances; and (viii) a Spill Prevent, Control and Countermeasure (SPCC) plan.