Granted Patent
Utility
US 4,436,638 · App. 06/288,110
Additive composition for release of stuck drill pipe
Inventors:
Thad O. Walker, Patricia C. Matthews
Patented Case
View Patent ↗
Granted: Mar 13, 1984
Filed: Jul 29, 1981
Inventors
Thad O. Walker
Patricia C. Matthews
Assignee (at issue)
Exxon Research and Engineering 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.