Granted Patent
Utility
US 5,955,401 · App. 08/649,097
Clay-free biodegradable wellbore fluid and method for using same fluid
Inventor:
W. Andrew Liao
Patented Case
View Patent ↗
Granted: Sep 21, 1999
Filed: May 17, 1996
Inventor
W. Andrew Liao
Assignee (at issue)
Baroid Technology, 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.