Granted Patent
Utility
US 4,404,111 · App. 06/232,456
N,N-Dimethylacrylamide/2-acrylamido-2-methylpropane sulfonic acid copolymers for enhanced petroleum recovery
Inventors:
Le-Khac Bi, Mary E. Dillon, Clyde L. Sharik
Patented Case
View Patent ↗
Granted: Sep 13, 1983
Filed: Feb 6, 1981
Inventors
Le-Khac Bi
Mary E. Dillon
Clyde L. Sharik
Assignee (at issue)
Atlantic Richfield 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.