Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4562560 | Method and means for transmitting data through a drill string in a borehole | — | 1985-12-31 |
| 4492276 | Down-hole drilling motor and method for directional drilling of boreholes | — | 1985-01-08 |
| 4491738 | Means for generating electricity during drilling of a borehole | — | 1985-01-01 |
| 4485879 | Downhole motor and method for directional drilling of boreholes | Robijn Feenstra | 1984-12-04 |
| 4465147 | Method and means for controlling the course of a bore hole | Robijn Feenstra | 1984-08-14 |