POLYPAC UL Ultralow-Viscosity Polyanionic Cellulose | SLB


Ultralow-viscosity polyanionic cellulose

Schlumberger Oilfield Services

POLYPAC UL ultralow-viscosity polyanionic cellulose is a high-quality, water-soluble polymer designed to control fluid loss. Because it is an ultralow-viscosity additive, it causes a minimal increase in viscosity in water-based muds.

Typical Physical Properties
Physical appearance White free-flowing powder
Specific gravity 1.5–1.6
pH (1% solution) 6.5–8.0


POLYPAC UL cellulose controls fluid loss in freshwater, seawater, KCl and salt muds. It forms a thin, resilient, low-permeability filter cake which minimizes the potential for differential sticking and the invasion of filtrate and mud solids into permeable formations. POLYPAC UL cellulose resists bacterial attack and does not require a biocide or preservative. It is effective in low concentrations, with the normal concentration to control fluid loss ranging from 0.25 to 1 lbm/bbl [0.71 to 2.85 kg/m3]. In saltwater and PAC-polymer systems, higher concentrations are required for encapsulation, with normal concentrations ranging from 1 to 3 lbm/bbl [2.85 to 8.6 kg/m3].

POLYPAC UL cellulose is an ultra-low additive, which generates less viscosity than regular POLYPAC additive. The viscosity generated depends on the solids concentration, salinity and makeup water chemistry.

POLYPAC UL cellulose is an anionic polymer that attaches to and encapsulates exposed shales and drill cuttings. This protective polymer “envelope” inhibits the dispersion of shale cuttings and restricts fluid interactions with exposed shales.

In saturated salt systems, POLYPAC UL cellulose tends to work significantly better than regular-viscosity PAC materials. For difficult filtration-control fluids, a combination of UL and regular-viscosity PAC products is generally more effective.


  • Effective in low concentrations to control fluid loss
  • Produces minimal viscosity increase
  • Encapsulates shale particles to inhibit swelling and dispersion
  • Resists bacterial attack; no biocide or preservative is necessary
  • Functions over a wide range of salinity and hardness
  • Effective over a wide range of pH levels
  • Has application in all water-based muds, ranging from low-solids, non-dispersed polymer systems to high-density, dispersed systems; compatible with all common mud-treating additives
  • Excellent environmental acceptability


  • Circulating temperature stability is approximately 300 degF [149 degC]
  • Effective in systems with a total hardness <1,000 mg/L (as calcium) but can be precipitated in the combined presence of high hardness and high pH

Toxicity and handling

Bioassay information is available upon request. Handle as an industrial chemical, wearing protective equipment and observing the precautions described in the safety data sheet.

Packaging and storage

POLYPAC UL cellulose is packaged in 50-lbm [22.7-kg] multiwall waterproof sacks. Store in a dry, well-ventilated area. Keep container closed. Store away from incompatibles. Follow safe warehousing practices regarding palletizing, banding, shrink-wrapping, and stacking.