Earth boring, well treating, and oil field chemistry
Patent class list (only not empty are listed)
Deeper subclasses:
Class / Patent application number | Description | Number of patent applications / Date published |
---|---|---|
507200000 | WELL TREATING | 943 |
507100000 | EARTH BORING | 465 |
507090000 | PREVENTING CONTAMINANT DEPOSITS IN PETROLEUM OIL CONDUITS | 76 |