M-I PAC R Technical-Grade Polyanionic-Cellulose Filtration-Control Additive | SLB


Technical-grade polyanionic-cellulose filtration-control additive

Schlumberger Oilfield Services

Tech-grade-quality M-I PAC R additive is useful in controlling filtration and increasing rheology in all types of water but is particularly effective in saltwater brines. M-I PAC R additive aids in dispersion control by attaching and encapsulating the drill solids. It can be used at all density ranges and functions effectively in dispersed and nondispersed systems.

Typical Physical Properties
Physical appearance White powder
Specific gravity 1.5 to 1.6
pH 6.5 to 8.0 (1% solution)


M-I PAC R additive controls fluid loss in freshwater, seawater, KCl, and saltwater drilling fluid systems. It aids in the formation of a tough, thin filtercake to minimize the potential for differential sticking. Recommended treatment is from 0.5 to 3.0 lbm/bbl [1.5 to 9.0 kg/m3] depending on the water type and the salt level for the control of fluid loss.

M-I PAC R additive is useful in viscosifying all types of water to create sufficient yield point to assist in the carrying capacity of solids for improved hole cleaning. Typically M-I PAC R additive provides a 15-cP viscosity and 30-lbm/100 ft2 [14.3-Pa] yield point with a concentration of 2.5 lbm/bbl [7.0 kg/m3] in freshwater without any clay.

Recommended concentrations for building viscosity range from 1.0 to 4.0 lbm/bbl [3.0 to 12.0 kg/m3]. Water hardness and salt level will affect the amount of M-I PAC R additive required.

M-I PAC R additive will create an envelope around exposed shales and cuttings to encapsulate them, reducing dispersion and permitting improvement of wellbore integrity. The encapsulation protects the shale from exposure to water.


  • Effective in controlling fluid loss
  • Resists attack from bacteria, requiring no preservatives or bactericide
  • Environmentally acceptable
  • Depending on water quality, provides viscosity
  • Functions at all ranges of pH levels in both dispersed and nondispersed fluids


  • Contains salt as a by-product of processing
  • High hardness [1,000 mg/L] will require precipitation of the Ca2+ and Mg2+ to improve performance
  • Temperature stability limitation of 250 degF [120 degC]; approaching this temperature, a thermal stabilizer, such as PTS-200 polymer temperature stabilizer, will be required

Toxicity and handling

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

Packaging and storage

M-I PAC R additive is packaged in 50-lbm [22.7-kg] multiwall paper sacks. Store in a dry location away from sources of heat or ignition, and minimize dust.