EXPLORATION AND PRODUCTION Administration and Finance Drilling Management North Administration andFinance Assistant Management Superintendence of Material Resources Monitoring and Control of Supplies Contracts

Exhibit 10.15

Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

EXPLORATION AND PRODUCTION

Administration and Finance Drilling Management

North Administration and Finance Assistant Management

Superintendence of Material Resources

Monitoring and Control of Supplies Contracts

Additional Agreement Number 5 (Five) for Extension of Time to the Public Work Contract on the basis of unit prices Number ###-###-#### celebrated on one hand by PEMEX – Exploration and Production, Public Decentralized Organism of the Federal Government- which on this document will be named “PEP”, and represented by the engineer Juan Alfredo Ríos Jiménez, who is in charge of the Drilling and Well Maintenance Northern Division Management and partly by Merco Ingeniería Industrial S.A. de C.V. and Forbes Energy Services LTD, who is hereby named “The Contractor”. The First one represented by Luis Lauro Moreno Ricart, in his character as Sole Administrator. The second one represented by José Andrés Suárez Canales in his character as Special Representative. In accordance with the following background, statements and clauses:

- B a c k g r o u n d -

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

The parties also convey on including 16 (sixteen) New Concepts, corresponding to the extraordinary items numbers: 6.9, 15.1, 15.2, 15.3, 15.4, 15.5, 15.6, 15.7, 15.8, 15.9, 15.10, 15.11, 15.12, 15.13, 15.14

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

and 15.5, as detailed in the Annex “B” Additional supplementing the Annex “B” and the Annex “DE-10A-1” supplementing the Annex “DE-10A to form part of this agreement.

Additionally the parties agree to extend the contract amount by an amount of $41,043,200.00 pesos (Forty one million, forty three thousand and two hundred 00/100 pesos) plus $21,000,000.00 USD (Twenty one million 00/100 USD) which added to the amount originally contracted of $234,256,757.01 pesos (Two hundred and thirty four million, two hundred and fifty six thousand, seven hundred and fifty seven 01/100 pesos) plus $48,842,604.99 USD (Forty eight million, eight hundred and forty two thousand, six hundred and four 99/100 USD) results in a further sum of $275,299,957.01 pesos (Two hundred and seventy five million, two hundred and ninety nine thousand, nine hundred and fifty seven 01/100 pesos) plus $69,842,604.99 USD (Sixty nine million, eight hundred and forty two thousand, six hundred and four 99/100 USD).

The rate of expansion is of 17.52% in pesos plus 43.00% in USD compared to the originally contracted amount.

The rate of expansion if of 13.29% over the period originally contracted.

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

The rate of expansion is of 50% which added to the 13.29% derived from the Agreement Number Three (3) results in a total percentage of expansion of 63.29% over the period originally contracted.

Through office number 227-21000 ###-###-####/2010 and 208-21000 ###-###-####-2010 the Operating Units of Tertiary Gulf Oil and Poza Rica – Altamira, respectively required the Contractual Services Assistant Management D.N. to perform the steps for the conclusion of a deadline extension and amount agreement to the contract ###-###-#### this in order to comply with the work of repair of wells listed in the Operative Program 2011 (POT-1 2011) of the Integral Active Tertiary Gulf Oil.

It is important to note that because this contract ended its term on December 31^st, 2010 bids have been scheduled for new contracts for Production Refunds (Packages I, II and III). The previous given to the implications that were raised at the time by the new rules and regulations in hiring matters of Pemex. Therefore a strategy was taken to continue this work by extending the deadline in terms and amount of the contract mentioned. Hence, due to the imminent expiration deadline of the contract and given that there was no budget authorization for the ruling of expansion in amount, the Contractual Service Assistant Management through Office ###-###-####-2010, dated on December 17^th, 2010, only required to the Superintendence of Material Resources D.N. the conclusion of the Agreement Four (4) of term expansion to the contract by 365 calendar days.

According to the POT-I 2011, in the Integral Active Tertiary Gulf Oil are programmed a total of 499 repairs of which 313 are major and 186 minor. Also in the Integral Active of Poza Rica – Altamira are programmed a total of 451 repairs of which 85 are major and 366 minor.

POT-I 2011 AIATG

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

POT I 2011 POZA RICA-ALTAMIRA

PEP lacks of available repair equipments under administration to operate in the Integral Active Tertiary Gulf Oil. Therefore, in order to monitor the operational program described above, that Active has scheduled interventions to be performed with the equipment which is under protection of the contract ###-###-####. This contract currently has a team of 8 wells repair equipment and operating assets in the Integral Active Tertiary Gulf Oil. They have been contributing to the compliance of the operational programs in this Active. According to the kind of intervention (minor or major repairs), two monthly interventions are performed with each equipment.

For all the mentioned above, in case of not having the amount for the referred contract, PEP would stop doing and average of 16 monthly repairs during the year 2011. This could lead to the Integral Active Tertiary Gulf Oil not being able to comply with the Required Programs by the High Direction of PEP. And since the Integral Active Tertiary Gulf Oil Project is a strategic project is of utmost importance to meet its established goals.

The Integral Active Poza Rica – Altamira to comply in a timely manner to the operational demand in order to deliver favorable contributions to wells production is required to have the Infrastructure Service, Services and 5 repair equipments, planning activities related to this contract in the following wells.

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

Currently the contract has had a total of $252,247,822.07 (Two hundred and fifty two million, two hundred and forty seven thousand, eight hundred and twenty two 07/100 pesos) plus $69,081,663.39 USD (Sixty nine million, eighty one thousand, six hundred and sixty three 39/100 USD).

In order of giving continuity and compliance with the PEP operational program concerning Repair Work and Maintenance of Oil Wells in the northern region, the Integral Active Tertiary Gulf Oil through the Tertiary Gulf Oil Project provided the funds required through the Verification of Resources for Contracts, Agreements and/or Acquisitions with Investment Budget with folio number PATG-114/10 (Table 1). The previous in order to cover an estimated 40% of the work stipulated in its POT-1 2011. Therefore, it is requested the extension in the contract amount No.  ###-###-#### for the amount of $60,000.000.00 USD (Sixty million 00/100 USD).

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

Table 1

The Integral Active Poza Rica – Altamira also provided the funds required through the Verification of Resources for Contracts Agreements and/or Acquisitions with Investment Budget with folio number PIN-034/11 (Table 2) for the amount of $515,521,944.84 pesos (Five hundred and fifteen million, five hundred and twenty one thousand, nine hundred and forty four 84/100 pesos).

The amount extension is required to be carried out in the following manner:

Derived from the formerly mentioned the amount of the contract is extended in $618,129,944.84 pesos (Six hundred and eighteen million, one hundred and twenty nine thousand, nine hundred and forty four 84/100 pesos) plus $50,000,000.00 USD (Fifty million 00/100 USD) being the new contract amount of $893,429,901.85 pesos (Eight hundred and ninety three million, four hundred and twenty nine thousand, nine hundred and one 85/100 pesos) plus $119,842,604.99 USD (One hundred and nineteen million, eight hundred and forty two thousand, six hundred and four 99/100 USD).

The preparation of this agreement involves no affect to the conditions referred to the essential characteristics and nature of the original contract purpose.

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

- S t a t e m e n t s -

PEP testifies that:

The engineer Juan Alfredo Ríos Jiménez is in charge of the Drilling and Well Maintenance Northern Division Management attached to the Unit of Drilling and Well Maintenance, in accordance to the approved designation by the PEP Board of Administration in Ordinary Session No. 135 dated on December 8^th, 2010 in terms of the Article 58, Fraction XI of the Federal State Entities Law. Also, credits his powers as General Representative for Administration Acts in representation of PEMEX Drilling and Production. The previous in accordance with the Public Deed Number 13,783 dated on February 25^th, 2011 granted before the Notary Public Alfredo Bazúa Witte B.S. in Law holder of the Public Notary 230 of the City of Mexico, Federal District.

The Contractor testifies that:

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

For all the above mentioned and based on the agreed in the Thirteenth and Fourteenth Clauses of the Contract and based on the Article 59 of the Law of Public Work and Same Related Services, the parties grant the following:

- C l a u s e s –

According to what stated in the background VII and IX of this contract, the parties agree on increasing the Contract amount in $618,129,944.84 pesos (Six hundred and eighteen million, one hundred and twenty nine thousand, nine hundred and forty four 84/100 pesos) plus $50,000,000.00 USD (Fifty million 00/100 USD) which added to the amount derived from the Agreement Number 1 (One) of $275,299,957.01 pesos (Two hundred and seventy five million, two hundred and ninety nine thousand, nine hundred and fifty seven 01/100 pesos) plus $69,842,604.99 USD (Sixty nine million, eight hundred and forty two thousand, six hundred and four 99/100 USD) result in a new amount of $893,429,901.85 pesos (Eight hundred and ninety three million, four hundred and twenty nine thousand, nine hundred and one 85/100 pesos) plus $119,842,604.99 USD (One hundred and nineteen million, eight hundred and forty two thousand, six hundred and four 99/100 USD).

The rate of expansion is 263.87% in pesos plus 102.36% in USD compared to the amount originally contracted, which added to the accumulated percentage of 17.52% in pesos plus 43% in USD derived from the Agreement Number 1 (One) result in a total rate expansion of 281.39% in pesos plus 145.36 in USD.

As a result of the above, the Second Clause that refers to the “Amount of the Contract” is modified and prevails as follows: The total amount of the present contract is of $893,429,901.85 pesos (Eight hundred and ninety three million, four hundred and twenty nine thousand, nine hundred and one 85/100 pesos) plus $119,842,604.99 USD (One hundred and nineteen million, eight hundred and forty two thousand, six hundred and four 99/100 USD) plus the Added Tax Value.

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

PEP and the CONTRACTOR agree that during the expansion of amount that takes place through this agreement remains the discount rate offered by the CONTRACTOR, accepted by PEP and accorded in the Agreement Number 4 (Four). Therefore, the work performed and invoiced in accordance with this agreement will be subject to such application. Subsisting in its literal application the provisions agreed for the discount rate.

The Contractor to ensure compliance with its obligations under this agreement agrees to deliver to the Superintendence of Material Resources of the North Administration and Finance Well Drilling and Maintenance Assistant Management located in the ground floor of the Administrative Building of the North Division Well Drilling and Maintenance Management, at the Colonia Herradura, area code 93370 of this city on the date of the execution of this agreement, an expansion in amount endorsement to the Bond Police(s) originally established due compliance in the clause Seventeenth of the Contract and the concerning to the compliance warranty and hidden vices warranty for an amount of $61,812,994.48 pesos (Sixty one million, eight hundred and twelve thousand, nine hundred and ninety four 48/100 pesos) plus $5,000,000.00 USD (Five million 00/100 USD) which equals a 10% of the extended amount accorded through this agreement. The previous indicates that they are supportive and inseparable of the original bond and also are committed to guarantee the compliance of the Contract, supporting the terms of this agreement. Aware that the lack of timely filing of such documents will endorse PEP to stop the payment of invoices for performed work under the extended amount that had been submitted or are submitted for collection. Up until those endorsements of policies are successfully delivered. Without that suspension generates the payment of financial charges for being a reason attributable to the Contractor itself and could be grounds for rescission.

With the exception of the modified clauses which must here be understood in the terms agreed remain without variation all the stipulations of the contract, its annexes, and modifying agreements as well as the execution time derived from the Agreement Number 4(Four) of 1,192 (one thousand and ninety two) calendar days counted from September 26^th, 2008 and consequently ending on December 31^st, 2011.

This document was read by the contracting parties which are duly aware of the content and scope of it and is signed in accordance in 3 copies in the city of Poza Rica de Hidalgo, Veracruz on March 24^th, 2011.

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

By PEMEX Exploration and Production

/s/ Juan Alfredo Ríos Jiménez

Juan Alfredo Ríos Jiménez

Well Drilling and Maintenance North Division Manager

Of the Well Drilling and Maintenance Assistant Management Unit

This page is part of the Agreement Number 5(Five) of the Contract Number ###-###-#### signed on March 24^th, 2011 which is made of 12(twelve) sheets.

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Additional Agreement Number 5 (Five) for Extension of Time

Contract ###-###-####

Merco Ingeniería Industrial S.A. de C.V./Forbes Energy Services LTD (Joint Proposal)

E l a b o r a t e d

/s/ Hugo Amaya Enderle

Hugo Amaya Enderle

Super Intendant of Material Resources

Le g a l   R e v i e w

/s/ Eduardo Montesinos Martínez B.S.

Eduardo Montesinos Martínez B.S.

Legal Services Assistant Manager

Northeast Region of Poza Rica

This page is part of the Agreement Number 5(Five) of the Contract Number ###-###-#### signed on March 24^th, 2011 which is made of 12(Twelve) sheets.

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