Toxic Components in Drilling Fluids

Because formulations for mud additives are continually undergoing change, the Drilling Representative should be aware of certain additives that are considered toxic. EPA priority pollutants include various trade metals; zinc, chromium, lead, mercury, cadmium, nickel, asbestos, and various phenol compounds. Chromium is a highly controversial issue; the EPA defines toxic chrome as Cr+6(or in a hexavalent state). In drilling fluids, the chrome exists in a trivalent state (Cr+3) and the process to oxidize the absorbed chrome back to a Cr+6 state is virtually impossible. Additives that contain chrome in the Cr+3 state are: chrome lignite and chrome lignosulfonate.

Aromatic hydrocarbons are among the most toxic to marine organisms and destructive to soils and groundwater. Other hydrocarbon products include: asphalt derivatives, foamers/defoamers, surfactants, emulsifiers and corrosion inhibitors. These can be added in small percentages without significantly reducing LC50 values, but the impact of each should be considered prior to treatment of the entire mud system. Bactericides and biocides are highly toxic; however, newer formulations have shown improved LC50 responses and therefore, greater acceptance in the industry. Completion fluids contain inorganic materials such as: zinc, bromine, chlorine, potassium, etc. and are regulated by most Federal and State Agencies. Completion fluid filtration control additives may contain chrome salts of up to 8.0% by weight.

The use of spotting fluids complicates matters as a fraction of the spot will always become blended with the active mud system, regardless of the amount of buffer zone recovered on either side. Generally, if the retort volume exceeds 2% oil (by volume), the amount absorbed on cuttings will be great enough to leave a visible sheen. Reduced toxicity mineral/vegetable oils may satisfy EPA guidelines, but a visible sheen in the marine environment will still direct unnecessary attention to the discharge and thus prevent discharge.

Because of the information available on drilling fluid toxicity in the marine environment, one can infer that disposal of drilling fluids and solids offshore is environmentally safe if approved by the EPA. Some EPA regions do not allow any discharges overboard, others require bioassay information for the drilling fluid prior to discharge, and some allow almost any discharge into state or federal waters. Many industry experts expect that sooner or later, the Federal EPA and related agencies will require all discharges to be "non-toxic" or hauled to shore for disposal. Moreover, it appears that state waters will follow suit. Thus, the ultimate fate of waste material generated in offshore drilling operations will need to be handled according to onshore disposal regulations.

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Responses

  • Paul Schuhmacher
    Is drilling fluid toxic?
    3 years ago
  • donata
    Is drilling fluid harmful?
    1 year ago
  • Lanny
    What is drilling fluid contains toxic chemicals?
    11 months ago
  • jimmy ketterman
    What harmful chemicals are in drilling muds?
    7 months ago
  • Zewdi
    Is drilling fluids used in oil well drilling considered a pollutant?
    5 months ago
  • Gringamor
    Is Drilling_fluid toxic?
    5 months ago
  • adonay
    How they drill for wells toxic chemical?
    1 month ago

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