CMCs and the closely related PACs are vital components for reducing fluid loss. Depending on the grade, they can also make an important contribution to the viscosity and the shale inhibitive properties of the drilling fluid.

Polyanionic cellulose (PAC) has been developed to meet the increasing demand being placed on polymers, which has pushed the adaptability of CMCs to their limits in certain circumstances.

PAC has been designed to take account of such factors as low solids content, clay stabilization, formation damage and temperature stability.

Akzo Nobel provides purified and semi-purified PAC grades.  All are suitable for use in any type of aqueous mud, from fresh to salt types.

STAFLO Regular and STAFLO Exlo
Premium PACs, with 99% active material, outperform most of the other PACs with regard to fluid-loss reduction, viscosity contribution and shale inhibition. Exlo, unlike the Regular grade, has little effect on the rheology of the system.

Table of STAFLO grades

Product type	Product name	Active contents (%), dry basis (typical)	Fluid-loss controller	Viscosifier	Shale inhibitor
PAC	Staflo Regular	99	*****	*****	*****
PAC	Staflo Exlo	99	****	**	***