| Relationships | Role | Relationship Start | Relationship End |
| Kavernen Bau- Und Betriebs-Gmbh | Parent | 12/31/1992 | 12/30/1993 |
| Preussag Aktiengesellschaft | Parent | 12/11/1981 | 12/30/1992 |
| Greylock Pipeline Inc. | Subsidary | 1/4/1984 | 11/27/1989 |
| Preussag Energy Ventures General Partnership | Subsidary | 1/4/1984 | 5/10/1989 |
| Acquisitions & Mergers | Role | Assets | Acct Method | Type | Transaction Date |
| Preussag Corp. Of Delaware | Seller | Discontinued | 12/31/1986 | ||
| Preussag Oil And Gas Production Inc. | Seller | Discontinued | 12/31/1986 | ||
| Preussag Oil And Gas Research Corp. | Seller | Discontinued | 12/31/1986 |