| Relationships | Role | Relationship Start | Relationship End |
| Corexcal, Inc. | Parent | 12/31/1983 | 12/1/1985 |
| Coparex International (Coparex) | Parent | 12/31/1980 | 12/30/1983 |
| Societe De Gestion Et D'interets Petroliers (Sogedip) | Parent | 12/31/1980 | 12/30/1982 |
| Cometra Oil Company, S.A. | Subsidary | 12/31/1984 | 12/30/1985 |
| Simpson Oil And Gas Co. | Subsidary | 12/31/1980 | 12/30/1982 |