EXHIBIT 7.1

Computation of ratio of earnings to fixed charges
(thousands of pesos)

|                                                                                |                                                                | Year ended December 31 |           
|------------------------------------------------------------------------------- | -------------------------------------------------------------- | ---------------------- | ----------
|
|Mexican GAAP                                                                    |                                                                |                        |           
|                                                                                | Fixed charges:                                                 |                        |           
|                                                                                | Interest capitalized in fixed assets                           |                        | 5,259,078 
|                                                                                | Interest in the specific reserve for exploration and depletion |                        | 48,132    
|                                                                                | Interest expense                                               |                        | 19,610,439
|                                                                                |                                                                |                        |           
|Total interest cost                                                             |                                                                | 24,917,649             |           
|                                                                                |                                                                |                        |           
|Total Fixed Charges                                                             |                                                                | 24,917,649             |           
|                                                                                |                                                                |                        |           
|Earnings after IEPS taxes and Hydrocarbon                                       |                                                                |                        |           
|Extraction duties                                                               |                                                                | (30,492,113            | )         
|Fixed Charges:                                                                  |                                                                |                        |           
|                                                                                | Interest cost net of amounts capitalized                       |                        | 19,610,439
|                                                                                |                                                                |                        |           
|Total Fixed Charges (Net of amounts capitalized)                                |                                                                | 19,610,439             |           
|                                                                                |                                                                |                        |           
|Earnings after taxes and duties plus fixed charges
(net of amounts capitalized) |                                                                | (10,881,674            | )         
|                                                                                |                                                                |                        |           
|                                                                                | Ratio of earnings to fixed charges                             |                        | (0.44     

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Computation of ratio of earnings to fixed charges
(thousands of pesos)

|                                                                                |                                          | Year ended December 31 |           
|------------------------------------------------------------------------------- | ---------------------------------------- | ---------------------- | ----------
|
|U.S. GAAP                                                                       |                                          |                        |           
|                                                                                | Fixed Charges:                           |                        |           
|                                                                                | Interest capitalized in fixed assets     |                        | 5,722,573 
|                                                                                | Interest expense                         |                        | 19,195,076
|                                                                                |                                          |                        |           
|Total interest cost                                                             |                                          | 24,917,649             |           
|                                                                                |                                          |                        |           
|Total Fixed Charges                                                             |                                          | 24,917,649             |           
|                                                                                |                                          |                        |           
|Income Earnings after taxes and duties                                          |                                          | (32,799,899            | )         
|Fixed Charges:                                                                  |                                          |                        |           
|                                                                                | Interest cost net of amounts Capitalized |                        | 19,195,076
|                                                                                |                                          |                        |           
|Total Fixed Charges (Net of amounts capitalized)                                |                                          | 19,195,076             |           
|                                                                                |                                          |                        |           
|Earnings after taxes and duties plus fixed charges
(net of amounts capitalized) |                                          | (13,604,823            | )         
|                                                                                |                                          |                        |           
|                                                                                | Ratio of earnings to fixed charges       |                        | (0.55     

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