Exhibit 10.15

Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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

LOGO

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 424048860 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 Managementand 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 -



| | I. | As of
September 26th2008,as a result of the International Competitive Bidding that takes place in accordance to the Free Trade Agreements signed by the United States of Mexico number 18575051-027-08, and based on the
following Articles of the Political Constitution of the United Mexican States: Article 134, Article 3 fraction II, Article 26 fraction I, Article 27 fraction I, Article 28, Article 30 fraction II item a) and Article 34 of the Law of Public Work
and Same Related Services, the parties concluded the contract in question for the execution of services related to: Repair and Maintenance Work on Wells in the Integral Active of Poza Rica-Alta Mira of the North Region (Package
1).
| | -- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | II. | The contract was signed for a total of: $234,256,757.01 pesos (Two hundred and thirty four million two hundred and fifty six thousand, seven hundred
and fifty seven pesos 01/100 pesos in addition to $48,842,604.99 USD (Forty eight million, eight hundred and forty two thousand, six hundred and four 99/100 USD) plus Value Added Tax and a deadline of 730 (seven hundred and thirty)
calendar days from September the 26th, 2008and consequently ending the day of September 25th, 2010.
| | --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



Page 1 de 12



---

Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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



| | III. | As part of the original contract the parties subscribed to the following annexes:
| | ---- | ---------------------------------------------------------------------------------



|             |  |                                                                                                                                                            
|------------ |  | -----------------------------------------------------------------------------------------------------------------------------------------------------------
|Annex A      |  | DRAWINGS AND THEIR RELATIONSHIP                                                                                                                            
|             | 
|Annex B      |  | GENERAL AND INDIVIDUAL SPECIFICATIONS OF THE PROJECT                                                                                                       
|             | 
|Annex B1     |  | STANDARDS                                                                                                                                                  
|             | 
|Annex DE-10  |  | CATALOG OF CONCEPTS                                                                                                                                        
|             | 
|Annex DE-10A |  | CATALOG OF UNIT PRICES                                                                                                                                     
|             | 
|Annex DT12   |  | SCHEDULED PROGRAM OF GENERAL EXECUTION OF THE WORK                                                                                                         
|             | 
|Annex DT3    |  | RELATIONSHIP OF MACHINERY AND/OR EQUIPMENT AND THEIR PHYSICAL LOCATION                                                                                     
|             | 
|Annex DT10   |  | LIST OF INPUTS INVOLVED IN THE INTEGRATION OF THE PROPOSAL                                                                                                 
|             | 
|Annex DSP    |  | MATERIALS AND INSTALLATION EQUIPMENT PROVIDED BY PEP                                                                                                       
|             | 
|Annex E    |  | MACHINERY AND/OR EQUIPMENT PROVIDED BY PEP (OTHER THAN THOSE OF THE PERMANENT INSTALLATION)                                                                
|             | 
|Annex G      |  | DOCUMENTATION REQUIRED BY FUNDING SOURCES                                                                                                                  
|             | 
|Annex G-1    |  | CERTIFICATE ON THE COUNTRY OF ORIGIN OF THE GOODS AND SERVICES                                                                                             
|             | 
|Annex S      |  | DUTIES OF SAFETY, OCCUPATIONAL HEALTH AND ENVIRONMENTAL PROTECTION OF THE SUPPLIERS OR CONTRACTORS OPERATING IN EXPLORATION AND PRODUCTION PEMEX FACILITIES
|             | 
|Annex BEO    |  | TERMS AND CONDITIONS USE OF THE ELECTRONIC LOG                                                                                                             
|             | 
|Annex DT-17  |  | PRIVATE AGREEMENT OF THE JOINT PROPOSAL                                                                                                                    



| | IV. | As of
September 4th,2009 both parties signed the Agreement Number 1 (One) Listing of Projects and New Concepts with Inclusion of Additional Increase whereby PEP and the Contractoragree to carry out the
work under this contract in the Integral Active Tertiary Gulf Oil same belonging to the northern region of Pemex Exploration and Production. Prevailing prices originally agreed. Therefore, the Contractor accepts not to make any
additional charge for the execution of work whenever they have the same nature and scope of the originally contracted.
| | --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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



Page 2 de 12



---

Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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 pesosplus 43.00% in USDcompared to the
originally contracted amount.



| | V. | As of
September 20th, 2010both parties signed the Agreement Number 2 (Two) for Extension of Time by which PEP and the Contractor agree to extend the deadline in 97 (Ninety seven) calendar days
which added to the original deadline in the contract of 730 (Seven hundred and thirty) calendar days result in a new deadline of 827 (Eight hundred and twenty seven) calendar days being a new contract termination day for
the day December 31st, 2010.
| | -- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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



| | VI. | As of
October 22nd, 2010both parties signed the Agreement Number Three (3) Listing of New Concepts without any Increase in Valueby which PEPand the Contractoragree to include 27 (Twenty seven)New Concepts as detailed in the Annex B Additional 1and the Annex DE-10A-1 which complements the Annex DE-10A which is an integral part of this agreement.
| | --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | VII. | As of
December 31st, 2010 both parties signed the Agreement
Number Four (4) Additional for Extension of Time by which the parties agree to extend the deadline in 365 (Three hundred and sixty five) calendar days which added to the original deadline in the Agreement Number Two
(2) of 827 (Eight hundred and twenty seven) calendar days result in a new deadline of 1,192 (One thousand one hundred and ninety two) calendar days being a new contract termination day for the day
December 31st, 2011.
| | ---- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



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---

Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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.



| | VIII. | Through office number 203-21000-21600-362/2011 dated on February 16th, 2011Office Number 203-21600-0243-2011 dated on
February 18th, 2011and Technical Opinion, the Contractual Services North Division Assistant Management required the Administration and Finance North Assistant Management the preparation of an agreement for extension to the
contract 424048860. The above in accordance with the following justification contained in the technical opinion:
| | ----- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Through office number 227-21000-21700-2176/2010 and 208-21000-21600-3389-2010 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 424048860 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 31st, 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 203-21600-2926-2010, dated on December 17th, 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



|      |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |       |    |  |  |  |    |  |  |  |    |  |  |  |     | 
|----- |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | ----- | -- |  |  |  | -- |  |  |  | -- |  |  |  | --- | 
|AIATG |  | JUN |    |  | FEB |  |    | MAR |  |  | APR |  |  | MAY |    |  | JUN |  |    | JUL |  |  | AGU |  |  | SEP |    |  | OCT |  |    | NOV |  |  | DEC |  |  | TOTAL |   
|DRILL |  |     | 15 |  |     |  | 15 |     |  |  | 15  |  |  |     | 16 |  |     |  | 14 |     |  |  | 14  |  |  |     | 15 |  |     |  | 15 |     |  |  | 16  |  |  |       | 13 |  |  |  | 14 |  |  |  | 16 |  |  |  | 178 | 
|COMP  |  |     | 41 |  |     |  | 45 |     |  |  | 43  |  |  |     | 36 |  |     |  | 37 |     |  |  | 23  |  |  |     | 17 |  |     |  | 14 |     |  |  | 16  |  |  |       | 17 |  |  |  | 15 |  |  |  | 15 |  |  |  | 319 | 
|RMA   |  |     | 19 |  |     |  | 26 |     |  |  | 26  |  |  |     | 28 |  |     |  | 25 |     |  |  | 26  |  |  |     | 25 |  |     |  | 30 |     |  |  | 26  |  |  |       | 27 |  |  |  | 27 |  |  |  | 28 |  |  |  | 313 | 
|RME   |  |     | 9  |  |     |  | 14 |     |  |  | 16  |  |  |     | 17 |  |     |  | 18 |     |  |  | 18  |  |  |     | 15 |  |     |  | 14 |     |  |  | 15  |  |  |       | 18 |  |  |  | 16 |  |  |  | 16 |  |  |  | 186 | 



|      |  |                                      |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |       |    |  |  |  |    |  |  |  |    |  |  |  |     | 
|----- |  | ------------------------------------ |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | ----- | -- |  |  |  | -- |  |  |  | -- |  |  |  | --- | 
|RMA   |  | PROYECTO                             |  | JUN |    |  | FEB |  |    | MAR |  |  | APR |  |  | MAY |    |  | JUN |  |    | JUL |  |  | AGU |  |  | SEP |    |  | OCT |  |    | NOV |  |  | DEC |  |  | TOTAL |   
|[11A] |  | AGUA FRIA-COAPECHCA-TAJIN            |  |     | 15 |  |     |  | 8  |     |  |  | 12  |  |  |     | 10 |  |     |  | 18 |     |  |  | 12  |  |  |     | 12 |  |     |  | 15 |     |  |  | 19  |  |  |       | 20 |  |  |  | 15 |  |  |  | 18 |  |  |  | 174 | 
|[11D] |  | AMATITLAN-PROFETA-TZAPOTEMPA-VINAZCO |  |     | 2  |  |     |  | 12 |     |  |  | 10  |  |  |     | 17 |  |     |  | 7  |     |  |  | 14  |  |  |     | 13 |  |     |  | 15 |     |  |  | 2   |  |  |       | 1  |  |  |  |   |  |  |  |   |  |  |  | 93  | 
|[11E] |  | INTEGRAL COYULA-JAPETO               |  |     | 2  |  |     |  | 2  |     |  |  | 1   |  |  |     |   |  |     |  |   |     |  |  |    |  |  |     |   |  |     |  |   |     |  |  |    |  |  |       |   |  |  |  |   |  |  |  |   |  |  |  | 5   | 
|[11G] |  | AREA 5 CHICONTEPEC                   |  |     |   |  |     |  | 4  |     |  |  | 3   |  |  |     | 1  |  |     |  |   |     |  |  |    |  |  |     |   |  |     |  |   |     |  |  | 5   |  |  |       | 6  |  |  |  | 12 |  |  |  | 10 |  |  |  | 41  | 
|      |  | TOTAL RMA                            |  |     | 19 |  |     |  | 26 |     |  |  | 26  |  |  |     | 28 |  |     |  | 25 |     |  |  | 26  |  |  |     | 25 |  |     |  | 30 |     |  |  | 26  |  |  |       | 27 |  |  |  | 27 |  |  |  | 28 |  |  |  | 313 | 



Page 4 de 12



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Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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



|      |  |                                      |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |       |    |  |  |  |    |  |  |  |    |  |  |  |     | 
|----- |  | ------------------------------------ |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | ----- | -- |  |  |  | -- |  |  |  | -- |  |  |  | --- | 
|RME   |  | PROYECTO                             |  | JUN |    |  | FEB |  |    | MAR |  |  | APR |  |  | MAY |    |  | JUN |  |    | JUL |  |  | AGU |  |  | SEP |    |  | OCT |  |    | NOV |  |  | DEC |  |  | TOTAL |   
|[11A] |  | AGUA FRIA-COAPECHCA-TAJIN            |  |     | 3  |  |     |  | 8  |     |  |  | 8   |  |  |     | 8  |  |     |  | 8  |     |  |  | 6   |  |  |     | 1  |  |     |  |   |     |  |  | 2   |  |  |       | 6  |  |  |  | 4  |  |  |  | 2  |  |  |  | 56  | 
|[11D] |  | AMATITLAN-PROFETA-TZAPOTEMPA-VINAZCO |  |     | 6  |  |     |  | 6  |     |  |  | 8   |  |  |     | 9  |  |     |  | 8  |     |  |  | 9   |  |  |     | 10 |  |     |  | 10 |     |  |  | 12  |  |  |       | 9  |  |  |  | 9  |  |  |  | 14 |  |  |  | 110 | 
|[11E] |  | INTEGRAL COYULA-JAPETO               |  |     |   |  |     |  |   |     |  |  |    |  |  |     |   |  |     |  | 2  |     |  |  | 3   |  |  |     |   |  |     |  | 4  |     |  |  | 1   |  |  |       | 3  |  |  |  | 3  |  |  |  |   |  |  |  | 16  | 
|[11G] |  | HUMAPA-BORNITA                       |  |     |   |  |     |  |   |     |  |  |    |  |  |     |   |  |     |  |   |     |  |  |    |  |  |     | 4  |  |     |  |   |     |  |  |    |  |  |       |   |  |  |  |   |  |  |  |   |  |  |  | 4   | 
|      |  | TOTAL RME                            |  |     | 9  |  |     |  | 14 |     |  |  | 16  |  |  |     | 17 |  |     |  | 18 |     |  |  | 18  |  |  |     | 15 |  |     |  | 14 |     |  |  | 15  |  |  |       | 18 |  |  |  | 16 |  |  |  | 16 |  |  |  | 186 | 
|      |  |                                      |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |       |    |  |  |  |    |  |  |  |    |  |  |  |     | 
|      |  |                                      |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |       |    |  |  |  |    |  |  |  |    |  |  |  |     | 
|      |  | GRAN TOTAL                           |  |     | 28 |  |     |  | 40 |     |  |  | 42  |  |  |     | 45 |  |     |  | 43 |     |  |  | 44  |  |  |     | 40 |  |     |  | 44 |     |  |  | 41  |  |  |       | 45 |  |  |  | 43 |  |  |  | 44 |  |  |  | 499 | 

POT I 2011 POZA
RICA-ALTAMIRA



|               |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |     |    |  |     |  |    |     |  |  |     |  |  |       |    |  |  |  |    |  |  |  |    |  |  |  |     | 
|-------------- |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | --- | -- |  | --- |  | -- | --- |  |  | --- |  |  | ----- | -- |  |  |  | -- |  |  |  | -- |  |  |  | --- | 
|ADMINISTRACION |  | JUN |    |  | FEB |  |    | MAR |  |  | APR |  |  | MAY |    |  | JUN |  |    | JUL |  |  | AGU |  |  | SEP |    |  | OCT |  |    | NOV |  |  | DEC |  |  | TOTAL |   
|RMA            |  |     | 4  |  |     |  | 9  |     |  |  | 12  |  |  |     | 9  |  |     |  | 5  |     |  |  | 6   |  |  |     | 7  |  |     |  | 8  |     |  |  | 3   |  |  |       | 6  |  |  |  | 8  |  |  |  | 8  |  |  |  | 85  | 
|RME            |  |     | 26 |  |     |  | 30 |     |  |  | 31  |  |  |     | 32 |  |     |  | 30 |     |  |  | 32  |  |  |     | 24 |  |     |  | 24 |     |  |  | 30  |  |  |       | 34 |  |  |  | 39 |  |  |  | 34 |  |  |  | 366 | 
|SUMA           |  |     | 30 |  |     |  | 39 |     |  |  | 43  |  |  |     | 41 |  |     |  | 35 |     |  |  | 38  |  |  |     | 31 |  |     |  | 32 |     |  |  | 33  |  |  |       | 40 |  |  |  | 47 |  |  |  | 42 |  |  |  | 451 | 

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 424048860. 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.



|                      |  |                       |  |                   
|--------------------- |  | --------------------- |  | ------------------
|Well                  |  | Well                  |  | Well              
|                      |  |                      
|1 Presidente Alemán 2 |  | 17 Nuevo Progreso 7   |  | 33 Xocotla 120    
|                      |  |                      
|2 Poza Rica 81        |  | 18 Ezequiel Ordoñez 5 |  | 34 Xocotla 117    
|                      |  |                      
|3 Mecatepec 81        |  | 19 Escolín 161        |  | 35 Xocotla 118    
|                      |  |                      
|4 Escolín 122         |  | 20 Mecatepec 13       |  | 36 Xocotla 101    
|                      |  |                      
|5 Escolín 240         |  | 21 Escolín 121        |  | 37 Santa Águeda 28
|                      |  |                      
|6 Escolín 138         |  | 22 Escolín 36         |  | 38 Santa Águeda 66
|                      |  |                      
|7 Escolín 102         |  | 23 Escolín 23         |  | 39 Santa Águeda 56
|                      |  |                      
|8 Escolín 238         |  | 24 Talaxca 5          |  | 40 Santa Águeda 30



Page 5 de 12



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Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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



|                        |  |                       |  |                        
|----------------------- |  | --------------------- |  | -----------------------
|9 Poza Rica 308         |  | 25 Talaxca 6          |  | 41 Tihuatlán 105       
|10 Castillo de Teayo 16 |  | 26 Poza Rica 187      |  | 42 Tihuatlán 102       
|11 Castillo de Teayo 11 |  | 27 Tejada 4           |  | 43 Castillo de Teayo 14
|12 Santa Águeda 44      |  | 28 Ezequiel Ordoñez 6 |  | 44 Castillo de Teayo 13
|13 San Andrés 259       |  | 29 Mozutla 6          |  | 45 Poza Rica 384       
|14 Poza Rica 304        |  | 30 Santa Águeda 67    |  | 46 San Andrés 49       
|15 Poza Rica 373        |  | 31 San Andrés 320 A   |  | 47 San Andrés 351      
|16 Ezequiel Ordoñez 2   |  | 32 San Andrés 102     |  | 48 Remolino 12         

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. 424048860 for the amount of $60,000.000.00
USD (Sixty million 00/100 USD).



|     |  |            |  |                           |  |                 |  |                  |  |                    |  |            |  |  |               | 
|---- |  | ---------- |  | ------------------------- |  | --------------- |  | ---------------- |  | ------------------ |  | ---------- |  |  | ------------- | 
|YEAR |  | CONCEPTUAL |  | FUND                      |  | FUNCTIONAL AREA |  | CENTERMANAGEMENT |  | FINANTIAL POSITION |  | USD AMOUNT | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD8R00QA10840T |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD1600QA12030X |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD1E00QA127B9E |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD1600QA12031W |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD0100PD12006A |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD0100PD12140E |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD0100PD12823S |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD0100PD11130M |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD0100PD127903 |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD0600PA11130Q |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD0600PA11131R |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DD0600PA11131S |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DP0000PH522300 |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DP0000PH520000 |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DP0000PH527900 |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|2011 |  | 11D        |  | TERTIARY GULF OIL PROJECT |  | PEF             |  | 11DP0000PH517500 |  | 2253220022721800   |  | 314302515  |  |  | 3,750,000.00  | 
|     |  |            |  |                           |  |                 |  |                  |  |                    |  | TOTAL      |  |  | 60,000,000.00 | 



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Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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).



|     |  |            |     |      |  |                           |  |                   |  |                    |  |                  |  |           |  |               
|---- |  | ---------- | --- | ---- |  | ------------------------- |  | ----------------- |  | ------------------ |  | ---------------- |  | --------- |  | --------------
|YEAR |  | CONCEPTUAL |     | FUND |  | FUNCTIONAL AREA           |  | CENTER MANAGEMENT |  | FINANTIAL POSITION |  | PESOS AMOUNT    
|2011 |  |            | 11C |      |  | TERTIARY GULF OIL PROJECT |  | PEF               |  | 11CP0000PH527000   |  | 2253220022721800 |  | 314302515 |  | 463,969,750.36
|2011 |  |            | 11C |      |  | TERTIARY GULF OIL PROJECT |  | PEF               |  | 11CD0200PD208802   |  | 2253220022721800 |  | 314302515 |  | 51,552,194.48 
|     |  |            |     |      |  |                           |  |                   |  |                    |  |                  |  | TOTAL     |  | 515,521,944.84

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



|                                                                                               |  |        |                       | 
|---------------------------------------------------------------------------------------------- |  | ------ | --------------------- | 
|DESCRIPTION                                                                                    |  | AMOUNT |                      
|UOATG Increase                                                                                 |  |        |                       | 
|                                                                                               | 
|Amount Increase in National Currency                                                           |  |        | $ 102608,000.00 M.N. | 
|                                                                                               | 
|Total of dollars approved according to the exchange rate of the day of the bid opening 10.2608 |  |        | $ 10000,000.00 USD   | 
|                                                                                               | 
|Amount Increase in US dollars                                                                  |  |        | $50000,000.00 USD    | 
|                                                                                               | 
|USD TOTAL UOATG                                                                                |  |        | $60000,000.00        | 
|                                                                                               | 
|Amount Increase in National Currency                                                           |  |        | $ 515521,944.84 M.N. | 

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 424048860

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



| | IX. | For the compliance of this agreement there is a sufficient budget under the Poza Rica Integral Project 11-C and the Tertiary Gulf Oil Integral Project 11D through the
financial position 314302515 and the Management Centers 2253220022721800 and 2383210120821800.
| | --- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

- 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. 135dated on December 8th, 2010in 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 25th, 2011granted before the Notary Public Alfredo Bazúa Witte B.S. in Lawholder of the Public Notary 230of the City of Mexico,
Federal District.

The Contractor testifies that:



| | 1. | Luis Lauro Moreno Ricartcredits his presence and faculties as Sole Administratorof Merco Ingeniería Industrial S.A. de C.V.through testimony of the Public Deed Number 2,053dated on September 5th, 2003. Those were granted before Jacinto Flores Peña B.S. in Law,Notary Public Number 115of the City of Reynosa Tamaulipas,who is enrolled in the Public Register of Commerce
of Reynosa Tamaulipas,under the number 775volume 2-016 section of commerce dated on October 1st, 2003.And they have not been revoked, modified or limited in any way.
| | -- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | 2. | José Andrés Suárez Canales credits his presence and faculties as Special Representative of Forbes Energy Services
LTD, through the Affidavit Number 12394 dated on October 6th, 2009granted before A. Ramses Capitanachi López B.S., Notary Public Number 7 of the Seventh Attorney Demarcation of the State
of Veracruz, which is properly registered in the Public Register of Property and Commerce of Poza Rica, Veracruz, in the commercial electronic folio number 7322*7 dated on October 22nd, 2009.
| | -- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



Page 8 de 12



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Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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 Contractand based on theArticle 59 of the Law of Public Work and Same Related Services,the parties grant the following:

- C l a u s e s 



| | First: | Additional Expansion of the Amount
| | ------ | ----------------------------------

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.



| | Second: | Total Amounts Modified
| | ------- | ----------------------

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.



| | Third: | Agreed Discount Rate Subsistence
| | ------ | --------------------------------



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Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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.



| | Fourth: | Endorsement Guarantees
| | ------- | ----------------------

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.



| | Fifth: | Other Provisions
| | ------ | ----------------

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 26th, 2008and consequently ending on December 31st,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 24th, 2011.



Page 10 de 12



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Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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



|                                            |  |  |  |                               
|------------------------------------------- |  |  |  | ------------------------------
|By Merco Ingeniería Industrial S.A. de C.V. |  |  |  | By Forbes Energy Services LTD 
|                                            |  | 
|/s/ Luis Lauro Moreno Ricart                |  |  |  | /s/ José Andrés Suárez Canales
|                                            |  | 
|Luis Lauro Moreno Ricart                    |  |  |  | José Andrés Suárez Canales    
|                                            |  | 
|Sole Administrator                          |  |  |  | Special Representative        

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



|                                 |  |  |  |                           
|-------------------------------- |  |  |  | --------------------------
|A d m i n i s t r a t i v e      |  |  |  | T e c h n i c a l         
|                                 |  | 
|/s/ Oscar Vincent Ávila          |  |  |  | /s/ Luis Ángel Ayala Gómez
|                                 |  | 
|Oscar Vincent Ávila              |  |  |  | Luis Ángel Ayala Gómez    
|                                 |  | 
|North Administration and Finance |  |  |  | Contractual Services      
|                                 |  | 
|Assistant Manager                |  |  |  | Assistant Manager         
|                                 |  | 
|                                 |  |  |  | P.M.P., D.N.              

This page is part of
the Agreement Number 5(Five) of the Contract Number 424048860 signed on March 24th, 2011 which is made of 12(twelve) sheets.



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Additional Agreement Number 5 (Five) for Extension of Time

Contract 424048860

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 424048860 signed on March 24th,
2011 which is made of 12(Twelve) sheets.



Page 12 de 12