Category: drilling fluids waste management

1. Handling Drilling Fluid Products and Cuttings

Working with drilling fluids can be hazardous. Some drilling-fluid products emit noxious or hazardous vapors that may reach levels that exceed the maximum recommended short-term or long-term safe exposure limits. Some shale and corrosion inhibitors and some oil-base mud emulsifiers tend to produce ammonia or other hazardous volatile amines, particularly in hot areas on a rig. Other products are flammable or combustible (flash point <140F), so that they too must be handled with caution. Thus, proper ventilation is vital in the mud pit areas and around the solids-control equipment.

Various mud products, brines, cleaning agents, solvents, and base oils commonly found on drill rigs are irritating or even hazardous to body tissues. Cuttings may be coated with these materials, too. Consequently, proper protective equipment should be worn for hands, body, and eyes when working around solids-control devices, even though the protective equipment may be inconvenient or uncomfortable.

2. Drilling Fluid Product Compatibility and Storage Guidelines

Mud products and test reagents can be particularly hazardous when stored improperly. As in any well-run chemistry laboratory, materials on the rig that are chemically incompatible should be stored apart from each other, and preferably in separate spill trays (secondary containment vessels). Some general storage guidelines are given in Table 2.3. Mud products and test reagents are classified into six hazard groups, in decreasing order of hazard risk (priority)—reactive/oxidizer, toxic, flammable, acids and bases, unknown, and nonhazardous—and each group should be segregated from the others. There should be very little or no material on the rig that falls into the reactive/oxidizer category. Acids and bases, though grouped together, should be placed in separate spill trays.

Table 2.3

Hazard Classification of Chemical Reagents and Mud Products

Chemical Segregation Guidelines

Safe storage practices require that materials be separated according to chemical compatibility and hazard class. The following hazard classes should be used for segregating the waste of decreasing hazard potential. Each hazard class of chemicals should be stored in a separate secondary containment labeled with the hazard class name. The containment vessels for hazard classes containing primarily solids (e.g., nonhazardous materials) should be placed above all others. Priority 3 materials should be isolated from the flammables cabinet. The secondary containment vessel for the oxidizer hazard classes should be made of metal and sit on a metal shelf.

Hazard Class	Definition	Example
Water/air	Materials that are potentially explosive, react violently, or generate toxic vapors when allowed to come in contact with air or water	Acetyl chloride, sodium metal, potassium metal, phosphorus (red and white),inorganic solid peroxides
Oxidizers,inorganic salts	Specific listed inorganic compounds that react vigorously with organic materials and/or reducing agents	Inorganic liquid peroxides, chlorates, perchlorates, persulfates, nitrates, permanganates, bleach
Oxidizers,inorganic acids (liq)	Inorganic liquids with pH<2 and strong tendency to oxidize organics	Perchloric, pitric, concentrated sulfuric, bromic, hypochlorous
Oxidizers, organic	Specific ‘‘listed’’ organic compounds that react vigorously with organic materials and/or reducing agents	Organic peroxides
Toxic materials, metals	Materials that contain specific ‘‘listed’’ water-soluble or volatile, nonoxidizing/ nonreacting metallic compounds that are regulated at levels below a few mg/L	Metals and water-soluble compounds of arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury,thallium (e.g., chrome lignosulfonate(CLS) and materials contamined with CLS.
Toxic materials, organic reagents	Specific ‘‘listed’’ compounds whose concentrations in wastes are regulated at levels of 0.1 to 200 mg/L	Phenol, biocides, cyanides, propargyl alcohol, carbon disulfide
Flammable and combustible liquids	Nonhalogenated, pourable, organic liquids with flashpoint <140_F (classes I and II)	Acetone, xylene, toluene, methanol, most organic oils, oil-based mud, brine/oil mixtures, oily cuttings solvent wash,invert mud emulsifiers and wetting agents, some lubricants
Halogenated liquids	Halogenated organic liquids, whether flammable or not	Chloroform, methylene chloride
Acids, organic (liq)	Organic liquids with pH<2	Acetic, butyric, formic
Acids, inorganic mineral (liq) and some concentrated brines	Inorganic liquids with pH<2, generally acids and certain salts	Hydrochloric, hydrobromic, hydrofluoric, dilute sulfuric, phosphoric, conc. brines (low pH, e.g., bromides and iodides)
Bases, organic (liq)	Organic liquids with pH>12.5	Amines, hydrazines
Bases, inorganic (liq)	Inorganic liquids with pH>12.5	Ammonia, ammonium hydroxide, sodium hydroxide, potassium hydroxide
Unclassified materials (hazardous and nonhazardous)		Calorimetric ampoules (ammonia and phosphate); mercury thermometers; salt gel (attapulgite); chemical spill kits, corrosion inhibitors, field product samples, HTCE residuals, well-cleaning chemicals, some shale inhibitors, tar
Nonhazardous materials, salts, clays, etc.	Miscellaneous materials that do not exhibit any of the hazards identified in categories 1–10, including nonoxidizing salts with 2<pH<12.5 (if in solution)	Most clays; nonflammable/noncombustible/nontoxic polymers (HEC, CMC,PAC); chrome-free lignosulfonates;most empty containers;chrome-free freshwater test fluids, filter cakes, filter media, retort solids residue; solid or aqueous chlorides, formates,carbonates,acetates, dilute bromides, and iodides

3.Waste Management and Disposal

The drilling-fluid program should address environmental issues concerned with the discharge of drilling fluid, products, and removed solids. Personnel managing the solids-separation equipment must be very familiar with this part of the drilling-fluid program and have a good

understanding of governmental regulations and operator requirements. Many drilling operations have strategies in place for drilling-fluid recovery and will have established some general guidelines for the disposal of materials classified as waste. However, situations can arise that present the engineer managing the solids-control equipment with the issue of whether to discard or recycle some types of waste and how to do it. If disposal costs are not a factor, then all waste can be disposed of and treated, if necessary, onsite or sent to a processor offsite. However, if it is possible to recycle some of the products to the mud system, it may prove economical to do so [Hollier et al]. Table 2.4 contains some general guidelines approved in the state of Texas for recycling and disposing of waste from a drilling operation. Definitions used in those guidelines for hazardous, class 1, class 2, and class 3 wastes are given below. Solid waste is classified as hazardous by the U.S. Environmental Protection Agency if it meets any of the following four conditions:

. The waste exhibits ignitability, corrosivity, reactivity, or toxicity.

. The waste is specifically listed as being hazardous in one of the four tables of 40 CFR 261: [Code of Federal Regulations]

1. Hazardous wastes from nonspecific sources (40 CFR 261.31)
2. Hazardous wastes from specific sources (40 CFR 261.32)
3. Acute hazardous wastes (40 CFR 261.33(e))
4. Toxic hazardous wastes (40 CFR 261.33(f)).

. The waste is a mixture of a listed hazardous waste and a nonhazardous waste.

. The waste has been declared to be hazardous by the generator.

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