1. n. [Drilling Fluids]
A test performed in a specialized filtration-type apparatus (particle-plugging apparatus) to determine the effectiveness of additives to prevent fluid loss into a permeable medium
Alternate Form: particle-plugging test
See: sintered
2. n. [Drilling Fluids]
A laboratory test used to determine if a drilling fluid blocks movement of filtrate through pore spaces of a shale sample. The PPT device monitors the increase in pore pressure in a shale when exposed to a drilling fluid over a period of time. Shale cores from 1 to 3-inches long are fitted into a modified Hassler cell that has sensitive pressure transducers in reservoirs on each end of the cell.

Reference: van Oort E, Hale AH, Mody FK and Roy S: "Transport in Shales and the Design of Improved Water-Based Shale Drilling Fluids," in SPE Drilling and Completion 11, no. 3 (September 1996): 137-146
Alternate Form: pore-pressure transmission