| Relationships | Role | Relationship Start | Relationship End |
| Tilassa Corporation S.A. | Parent | 12/31/1980 | 12/30/1983 |
| Simpson Oil And Gas Co. | Subsidary | 12/31/1980 | 12/30/1982 |
| Acquisitions & Mergers | Role | Assets | Acct Method | Type | Transaction Date |
| American Cometra, Inc. | Buyer | Discontinued | 12/31/1983 |