Granted Patent
Utility
US 4,447,338 · App. 06/292,235
Drilling mud viscosification agents based on sulfonated ionomers
Inventors:
Robert D. Lundberg, Thad O. Walker, Charles P. O'Farrell, Henry S. Makowski
Patented Case
View Patent ↗
Granted: May 8, 1984
Filed: Aug 12, 1981
Inventors
Robert D. Lundberg
Thad O. Walker
Charles P. O'Farrell
Henry S. Makowski
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.