| Top Driller Limited | Private company limited by shares | Live |
| Oil Driller Equipment Co., Limited | Private company limited by shares | Live |
| Ocean Driller III Limited | Private company limited by shares | Live |
| Ocean Driller II Limited | Private company limited by shares | Live |
| Ocean Driller I Limited | Private company limited by shares | Live |
| DRILLER'S EQUIPMENT (H.K.) LIMITED | Private company limited by shares | Dissolved |
| DRILLERS INTERNATIONAL COMPANY LIMITED | Private company limited by shares | Dissolved |
| UNITED DRILLERS LIMITED | Private company limited by shares | Dissolved |