Polyacrylamide as coating agent contains many functional groups.It can optimize mud performance by adjsting molecular structure.It has excellent inhibition，filtration lass reduction，lubricity，high temperature resistance，calcium and magnesiumresistance， high salt resistance and  other comprehensive properties.It can reduce the damage to reservoir permeability and as stable chemical performance .It is suitable for water-based and oil-based drilling mud systems. 

Application:(1)coating drilling cuttings,inhibiting dispersion, so as to control soild content;(2）inhibiting shale hydration expansion, stabilizing well wall,inhibiting shrinkage and dispersion collapse;(3)inhibting clay component espansion in oil gas reservoir;(4)reducing damage to permeability of oil and gas reservoir.(5)lubricate the bit to reduce the wear of the equipment;(6)improve the drlling speed and shorten the well construction period.