Granted Patent
Utility
US 4,650,593 · App. 06/834,487
Water-based drilling fluids having enhanced fluid loss control
Inventor:
Robert E. Slingerland
Patented Case
View Patent ↗
Granted: Mar 17, 1987
Filed: Sep 19, 1977
Inventor
Robert E. Slingerland
Assignee (at issue)
NL Industries, Inc.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.