Issued Patents 1989
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4888120 | Water-based drilling and well-servicing fluids with swellable, synthetic layer silicates | Claus-Peter Herold, Stephan van Tapavizca, Hans Dolhaine, Wolfgang von Rybinski, Winfried Wichelhaus | 1989-12-19 |
| 4851142 | Fluid loss additive for well drilling fluids | William Chrys Scoggins, Claus-Peter Herold | 1989-07-25 |
| 4802998 | Powder-form lubricant additives for water-based drilling fluids | Claus-Peter Herold | 1989-02-07 |