| Relationships | Role | Relationship Start | Relationship End |
| Preussag Aktiengesellschaft | Parent | 12/11/1981 | 12/30/1986 |
| Petroleum Enhanced Recovery Ltd. | Subsidary | 12/31/1984 | 12/30/1986 |
| Acquisitions & Mergers | Role | Assets | Acct Method | Type | Transaction Date |
| Preussag Oil And Gas Corp. | Buyer | Discontinued | 12/31/1986 |