Granted Patent
Utility
US 5,147,964 · App. 07/690,044
Method for reducing fluid loss from oilfield cement slurries using vinyl grafted wattle tannin
Inventors:
David A. Huddleston, Robert K. Gabel, Charles D. Williamson
Patented Case
View Patent ↗
Granted: Sep 15, 1992
Filed: Apr 23, 1991
Inventors
David A. Huddleston
Robert K. Gabel
Charles D. Williamson
Assignee (at issue)
Nalco Chemical Company
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.