FER-OX hematite weighting agent | SLB


Hematite weighting agent

Schlumberger Oilfield Services

FER-OX™ weighting agent is a high-quality, ground iron oxide with a specific gravity of 5.0 or above. Because of its high specific gravity, muds formulated with FER-OX weighting agent have lower solids content and frequently contribute to higher rates of penetration compared with barite muds.

It can be substituted for or blended with barite in all mud systems. FER-OX weighting agent is ground and processed to remove impurities, then classified to achieve the desired particle size distribution.

FER-OX is a mark of M-I L.L.C., an SLB company.

FER-OX weighting agent is applicable in all types of drilling fluids, including freshwater, seawater and oil-base muds. It can be used to increase the density of all drilling and completion fluids to 25 lbm/galUS [3.0 s.g.]. FER-OX weighting agent is most frequently used in high-density, oil-base muds.

Fluids weighted with FER-OX weighting agent contain fewer solids by volume than those weighted with barite, making higher mud weights possible. It is especially useful in high-density kill fluids.

  • Muds contain fewer solids than similar-density barite muds because of the 15% higher specific gravity
  • Rheological values in muds improve; generally plastic viscosities are 2–30% less than barite muds
  • Use of FER-OX muds can result in higher rates of penetration
  • FER-OX weighting agent has a higher bulk density than barite; so more weight is held in the same volume bulk tanks, and a smaller volume is  required at the wellsite
  • Less FER-OX weighting agent than barite is required to achieve the same mud weight, which reduces mud costs
  • It has a narrower particle-size distribution with a larger average particle size compared to barite
  • It is a harder mineral than barite, so it is more resistant to particle-size degradation
  • Approximately 97% acid soluble in 15% hydrochloric acid
  • Will partially scavenge hydrogen sulfide at neutral and low pH levels and can be regarded as a secondary sulfide scavenger. When  FER-OX weighting agent is used in H2S areas, a high pH should be maintained, and an appropriate primary scavenger should be used.
  • Can be environmentally preferred to barite in certain locations
Typical Physical Properties
Typical Physical Properties Physical appearance Dry: Red to brown powder
Typical Physical Properties Wet: Gray to black
Typical Physical Properties Muds: Deep reddish brown
Typical Physical Properties Specific gravity 5.0
Typical Physical Properties Bulk density 2,178 kg/m3[136 lbm/ft3]
Typical Physical Properties Particle hardness 5–6 Mohs hardness scale


  • Abrasion tests indicate that FER-OX weighting agent is more abrasive than barite. Stringent classification procedures for FER-OX weighting agent yield a  less abrasive weight material than competitive iron oxide products
  • The suspension of FER-OX weight material can require slightly higher gel strengths than those required for the suspension of barite

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

FER-OX weighting agent is packaged in 45.4 kg [100 lbm], multiwall, paper sacks and is available in bulk. 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.