Granted Patent
Utility
US 6,457,528 · App. 09/821,251
Method for preventing critical annular pressure buildup
Inventor:
John J. Staudt
Patented Case
View Patent ↗
Granted: Oct 1, 2002
Filed: Mar 29, 2001
Inventor
John J. Staudt
Assignee (at issue)
Hunting Oilfield Services (UK) Ltd.
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.