Granted Patent
Utility
US 6,468,945 · App. 09/474,164
Fluids for fracturing subterranean formations
Inventor:
Kewei Zhang
Patented Case
View Patent ↗
Granted: Oct 22, 2002
Filed: Dec 29, 1999
Inventor
Kewei Zhang
Assignee (at issue)
BJ SERVICES COMPANY CANADA
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.