OS POLYCAP - High Molecular Weight Polyacrylamide



Shale Inhibition

Shale inhibition additives are designed to stop or slow the chemical and mechanical disintegration of cuttings and wellbores while drilling with water-based muds. Depending upon the clay type a variety of inhibition mechanisms are employed using different chemistries. In all cases, regardless of the inhibition method it is important to maintain cuttings and wellbore integrity and protection. High molecular weight PHPA is the best encapsulating polymer for restricting both dispersion and hydration and is field-proven worldwide.


Product Information 

OS POLYCAP is a partially hydrolysed polyacrylamide (PHPA) of high molecular weight. OS POLYCAP is a highly soluble encapsulating polymer which provides shale stabilisation and cuttings integrity as well as fluid loss control and viscosity. OS POLYCAP is designed for use in fresh water, seawater, calcium/sodium brines and KCL mud systems.


Typical Physical Properties 

Appearance   -   White free flowing powder  

Molecular weight   -   > 8 million

Degree of Hydrolysis   -   25 – 35%                               

Moisture   -   <15%

Particle size   -   Min. 95% pass 20 mesh



OS POLYCAP provides good friction reduction and has good solubility in cold conditions.  OS POLYCAP is thermally stable up to 400oF and is compatible with all the commonly used water based mud additives.



OS POLYCAP is highly efficient in KCL mud systems where it coats the drill cuttings and acts by encapsulating active shale plates to form an impervious protective layer on both walls and the cuttings and thus inhibiting their dispersion and incorporation into the mud.


OS POLYCAP should be added through the hopper at 20 minutes per sack up to a concentration of 0.3 – 1.0 ppb depending upon operational need.



OS POLYCAP is packaged in 25 kg sacks.




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