Granted Patent
Utility
US 5,203,987 · App. 07/694,225
Method of upgrading residua
Inventor:
Emiliano de la Fuente
Patented Case
View Patent ↗
Granted: Apr 20, 1993
Filed: Apr 5, 1991
Inventor
Emiliano de la Fuente
Assignee (at issue)
Union Oil Company of California
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.