1. n. [Drilling Fluids]

A class of water muds that use partially hydrolyzed polyacrylamide (PHPA) as a functional additive, either to control wellbore shales or to extend bentonite clay in a low-solids mud. As a shale-control mud, PHPA is believed to seal microfractures and coat shale surfaces with a film that retards dispersion and disintegration. KCl is used as a shale inhibitor in most PHPA mud designs. In low-solids muds, PHPA interacts with minimal concentrations of bentonite to link particles together and improve rheology without increased colloidal solids loading.

References:

• Clark RK, Scheuerman RF, Raoth H and van Laar H: "Polyacrylamide-Potassium Chloride Mud for Drilling Water Sensitive Shales," Journal of Petroleum Technology 28, no. 6 (June 1976): 719-726.
• Fraser LJ: "New Method Accurately Analyzes PHPA's in Muds," Oil & Gas Journal 85, no. 27 (July 6, 1987): 39-42.

Alternate Form: PHPA

See related terms: acrylamide polymer,  acrylamide acrylate polymer,  acrylate polymer,  beneficiation,  clay extender,  clay-water interaction,  clear-water drilling,  encapsulation,  flocculant,  hardness ion,  low-solids mud,  potassium mud,  seawater mud