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Process Chemicals in the Oil and Gas Industry: Potential Occupational Hazards Merva K.W. Cottle and Tee L. Guidotti Toxicol Ind Health 1990 6: 41 DOI: 10.1177/074823379000600104 The online version of this article can be found at: http://tih.sagepub.com/content/6/1/41
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PROCESS CHEMICALS IN THE OIL AND GAS INDUSTRY: POTENTIAL OCCUPATIONAL HAZARDS MERVA K. W. COTTLE, PH.D. AND TEE L. GUIDOTTI, M.D. Occupational Health Program University of Alberta Faculty of Medicine 13-103 Clinical Sciences Bldg. Edmonton, Alberta T6G 2G3 Canada
Numerous chemicals are used in various processes of the oil and gas industry: drilling, cementing, completion, stimulation, and production. The number and the complexity of composition of process chemicals has increased greatly over the last three decades. The occupational hazards of exposure to these agents has received little attention. We reviewed the various processes in the industry, the type of chemicals used in each process, and some of their characteristics. We placed emphasis on those for which signijicant toxicity has been established or is suspected, and those for which there is incomplete information on their chemistry and health hazards. This report is intended to form a basis for a more complete survey of the process chemicals, and to draw attention to the possibilities for toxic exposure resulting from use of these agents in the oil and gas industry. The ultimate objective is to promote the safe use of these agents in the industry. During a study on the feasibility of a proposed occupational health study of workers in the gas industry in Alberta, we identified a need to examine and identify agents used in the oil and gas industry that could produce toxic effects with occupational exposure (Guidotti, 1986). “Process” or “production” chemicals used in the oil production industry number in the hundreds (Parker, 1983). They are used in the various processes necessary to the extraction of oil and gas resources: drilling, cementing, completion, stimulation and production; and are mostly specialty chemicals produced for the industry and marketed under trade names. Often, these chemicals are encountered only rarely outside the oil and gas industry. To ensure that these valuable chemicals are used safely, it is desirable to evaluate the potential hazard they may present. 1. Address correspondence to: Dr. Tee L. Guidotti. Occupational Health Program, University of Alberta Faculty of Medicine, 13-103 Clinical Sciences Bldg., Edmonton, Alberta T6G 2G3, Canada. 2. This paper was presented at the XVI Medichem International Congress on Occupational Health in the Chemical Industry, Helsinki, 1988. 3. Supported by the Tripartite Fund for Occupational Health and by the Acid Deposition Research Program of Alberta. Toxicology and Industrial Health, 6:1, pp. 41-56 Copyright 0 1990 Princeton Scientific Publishing Co., Inc. ISSN: 0748-2337
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In this paper, the term “process chemicals” will be used rather than “production chemicals” because the term “production” has a specific meaning within the oil industry, implying the sustained productivity of a well. This is only one part of the life cycle of a well, although the most important part if the well is successful. From the occupational health point of view, however, the other steps in well development are of equal or even greater interest. Compared to life-threatening occupational risks in the industry, such as that of a “knockdown” by hydrogen sulphide, the occupational hazards of process chemicals might appear to be of minor concern. However, some of these chemicals are known to have toxic properties and others have the potential for significant toxicity. Knowledge of their chemical nature and contaminants, particularly in preparations of commercial grade, is incomplete for many process chemicals. Moreover, mixtures which result from the simultaneous use of the process chemicals raise questions concerning the combined toxicity of the mixtures or products of reaction. We have reviewed specific chemicals available to the oil and gas industry in Alberta. We emphasize those with potential or established toxicity and those for which there is evidence of a potential occupational hazard. Because of the limited available knowledge of the chemistry of some of the products, this survey is not complete. It is intended to form the basis for developing a more complete toxicological profile of the process chemicals and to stimulate further investigation. We hope that further scrutiny and identification of “problem chemicals’’ may lead to a rational basis for making recommendations on exposure limits, use of protective equipment, alteration in the pattern of usage, and the substitution of less desirable products with safer materials. This report does not provide detailed toxicological information on the individual agents or classes of agents but directs the reader to useful reviews and recent reports on their toxicity.
BACKGROUND The use of chemicals in the oil industry to enhance recovery and production has increased since the 1930’s, when their usefulness was first recognized. The number of specialty chemicals available to the industry has increased greatly in the decades since. A large number of chemical agents are used. These range from complex organic polymers, for which the chemical structure is incompletely understood, to relatively simple inorganic compounds. Complex polymers have tended to replace some of the natural clays previously used. In addition to the primary agents of concern, there is the possibility that chemicals of commercial grade may contain contaminants. Others may be altered in the process itself, through chemical reaction and heat, resulting in complex secondary mixtures. For example, drilling mud and the other materials which ultimately are drained into the sump on the drilling site contain a myriad of chemicals.
A major difficulty in surveying the potential toxicity of process chemicals is the use of the trade names and limited information on the chemical constituents. With the intro-
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duction of the Workplace Hazardous Materials Information System (WHMIS) in Canada (Labour Canada, 1985), this information should become more accessible. Process chemicals used in the oil and gas industry have been categorized according to the various processes in which they find a purpose: drilling, cementing, completion, stimulation and production. Data on the chemicals is not easy to come by. General information on the chemicals used in water-based drilling has been obtained chiefly from the proceedings of a symposium organized by the Northwest Region of the Industrial Division of the Royal Society of Chemistry and edited by Ogden (1983). A number of these papers, specifically those of Bensted et al.; Gilby; Kelley; and Parker provide background on the general classes of chemicals (and in some cases more specific agents) used in the oil industry. A useful source of information on the use of specific chemicals found in Alberta is Oilweek, the industry journal (1986, 1987 & 1988). Runion (1988) listed substances that may be present in refining and allied petrochemical operations. Information available on these specific agents is in Tables 1 to 4, which should be regarded only as an initial survey, in time to be followed by an intensive and more detailed survey of the specific chemicals used. Guidotti (1986) included a brief survey of the process chemicals and their potential hazards in a study on the feasibility of occupational health studies in the industry in Alberta. Guidotti and Cottle (1986) discussed the issue in a scientific report based on this work. Divine and Barron (1987) indicated that formaldehyde, asbestos and mercury are hazardous exposures for pipeline and production workers. Runion (1988), in providing detailed information on health hazards in the petroleum industry, mentioned liquid or particulate additives to drilling mud as health hazards for petroleum industry drillers. Runion (1988) also surveyed the types of agents used in water-based drilling and production; and organized these based upon the processes involved.
PROCESSES Drilling fluid or ‘mud’ serves to circulate and to remove drilled cuttings from the base
of the bored hole, in order to maintain the stability of the hole and to cool the bit. The drilling mud may include liquids, solids, and even gases. Because of the explosive nature of gases under pressure, they are avoided as additives. Water-based mud consists of a liquid colloid, containing both inert and chemically reactive ingredients. Drilling chemicals are used to prepare and maintain drilling mud appropriate to the requirements of the site and may be classified according to use: weighting agents, viscosifiers, dispersants, fluid loss additives, commodity chemicals, biocides, corrosion inhibitors, surfactants and defoamers (Table 1). Cementing prevents borehole collapse, provides a base for drilling deeper, and may also serve to isolate non-producing from producing portions of the bore. Portland cement is used, with additives depending on the requirement. These are also classified by use: weighting agents, lost circulation materials (including accelerators and retarders of the cement-setting process), fluid loss additives, dispersants, and other additives (Table 2).
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TABLE 1 Process chemicals used in water-based drilling172 Type of Agent
Function
1. Weighting agents Provide optimal density 2. Viscosifiers
Provide fluid viscosity
Chemical
References
barytes (iron oxides) calcium carbonate lead sulphide powder
Parker, 1983 Oilweek, 1988
clays - bentonite - attapulgite
polymers
Parker, 1983
- polyacrylate - polyacrilamide - carbohydrate bipolymer - cellulose ethers (methyl, ethyl,
Oilweek, 1988
benzyl hydroxylethyl) - copolymer of vinyl acetate and maleic anhydride xanthum gum asbestos - shredded - pelletized
3. Dispensants (Thinners)
Dispense solid particles
complex organic compounds - lignite (mineral of the coal
series with complex organic acids often in the form of ferric/ferrochromeor chromefree lignosulphonates, might be considered polymers in chemical characteristics) - quebracho (crude tannic acid originating from Quercus, the oak tree)
Divine & Barron, 1987 Oilweek, 1988 Parker, 1983 Bensted et al., 1983 Oilweek, 1988
solvents - ethylene glycol and monobutyl
ether
- lecithin in diesel fuel (T.N. Biosperse3) - liquid organic thinner (T.N. Tackle3) - water solution of fluorocarbon (T.N. D-5g3)
Divine & Barron, 1987 Runion, 1988
polymers - polyacrylates Drilling mud functions to circulate and remove drilled cuttings, maintain stability of the bore hole, and cool the bit and tubing. *Herbicides are used in the vicinity of the well-site to limit vegetation growth but are not unique to the oil and gas industry. Trade name.
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TABLE 1 (continued) Type of Agent
Function
4.Fluidloss
Prevent loss of fluid from drilling mud
additives
Chemical
References
polymers
Parker, 1983
- polyacrylates - carboxymethyl cellulose
gums - xanthan - guar
pregelatinized starch and lignite asphalt
Oilweek, 1988
shredded cedar fibres 5 . Commodity chemicals
- Adjustment to
6. Biocidesl Bacteriostats
- Inhibit growth of
optimal pH micro-organisms such as: slimeproducing; iron bacteria, yeasts, filamentous fungi and sulphate reducing bacteria which may have serious effects by production of H2S
lime sodium hydroxide
Parker, 1988
chlorine or chlorine releasors e.g. chlorine, sodium hypochlorite, chloramines, chlorinated quanidines, chlorinated tripotassium tripotassium phosphate
Parker, 1983 Bessems and Clemmit, 1983
Oilweek, 1988
phenols - dichloroxylenol - benzyl cresol
organometallics - compounds of copper, tin and
Divine & Barron, 1987
mercury oxidants - peroxide
aldehydes
- formaldehyde - gluteraldehyde - paraformaldehyde
quaternary ammonium compounds - trimethylalkyl ammonium chloride
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TABLE 1 (continued) Type of Agent
Function
Chemical
References
7 . Corrosion inhibitors
Prevent or inhibit metal corrosion occurring in the presence of water by H,S and CO,
primary/polysubstituted monoamines and polyamines amides long-chain aliphatic diamines, long-carbon-chain imidazolines (sometimes reacted with ethylene oxide to yield poly oxyethylene) organic sulphophosphate (inhibits oxygen corrosion)
Parker, 1983 Kelley, 1983
quaternary ammonium compounds (trimethylalkyl) 8. Surfactants
Prevent formation of emulsions or precipitates
sulphonates
Parker, 1983
ethanolamines (mono & di) quaternary ammonium compounds
9. Defoamers
Deactivate surface active compounds in crude oil (entrapped gas is released)
phosphate esters (metallic soaps of fatty acids)
Parker, 1983
organic silicone compounds (dimethyl silicone)
CompletionlStimulation is the final drilling step in preparing a new well for production. Completion generally involves cleaning the drilled hole and possibly providing better communication with other layers of rocks in order to improve the flow of production. Stimulation usually involves acidising and hydraulic fracturing of the rock strata. Stimulation also improves productivity and may be important especially if drilling has damaged the rocks or if the rock is of poor quality. Acidising also entails the use of corrosion inhibitors, surfactants, chelating agents, fluid loss agents, clay stabilizers and polymers (Table 3). Production refers to the handling of all produced (pumped) and injected fluids, from the wellhead to the point of dispersal. This includes collection from individual wellheads into a common manifold system, oil/gas/water separation, and crude oil pumping and separating. Table 4 presents the typical chemicals that are used for a number of specific purposes, largely to maintain flow in this system. These include inhibitors of corrosion, scale, and wax formation. In addition, a score of processing chemicals are
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TABLE 2 Process chemicals used in cementing' Type of Agent
Function
Chemical
1. Weighting agents
- See Table 1 -
2. Fluidloss additives
- See Table 1 -
References
3. Lost circulation materials
Prevent loss of cement slurry to the formation
gilsonite mica
Parker, 1983
4. Accelerators
Speed up cement setting time
calcium chloride sodium silicate
Parker, 1983
5. Retarders
Extend cement setting time to allow cement pumping in deep wells
calcium lignosulphonate gums starches carboxymethylhydroxyethyl cellulose
Bensted et al., 1983 Parker, 1983
6. Dispersants and friction reducers
Improve flow or rheology of cement slurry
lignosulphonates
Parker, 1983
lignins polymers acrylamides
-
naphthalene condensation products aryl alkyl sulphonates I Cementing seals casing into boreholes prevents its collapse, provides a base to drill deeper and isolates producing from non-producing portions.
used in production to facilitate dehydration, defoaming, fluidity and startability of waxy crudes, and friction reduction. Deoiling of water, inhibition of bacterial activity (biocides), and deposition of gas hydrates and sulphur are also important aspects of maintaining production.
TOXICITY OF PROCESS CHEMICALS Many of the classes of agents used in all processes contain chemicals well recognized as toxic. There are also many of unknown toxicity and many for which their complete chemical composition, and therefore their possible toxicity, is not known. Those agents for which toxicity is known, suspected, or unknown due to uncertainty over composition are presented in Tables 5, 6 and 7, respectively. It is evident from Table 5 that the agents of most consistently documented toxicity are the biocides (used in drilling and production), the dispersants (used in drilling and cementing) and the drying agents (used in production). Many process chemicals fall into
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TABLE 3 Process chemicals used in completion and stimulation' Type of Agent
Function
Chemical
1. Viscosifiers
Reduce pressure losses due to friction while pumping
- See Table 1 -
2. Fluid loss additives
- See Table 1 -
3. Surfactants
- See Table 1 -
4.Clay stabilizers
Prevent or minimize clay hydration
potassium chloride
References
Parker, 1983
hydroxyalumina zirconium oxychloride
Completion and stimulation serve to clean drilled hole and improve quality and productivity.
the group of suspected toxicity, in Table 6. More information concerning toxicity is needed for these agents. Although the parent compounds used in preparing polymers (Table 7) may be toxic (some highly toxic), polymers, in general, exhibit low toxicity. A recent paper (Darby, 1987) on the safety of polymers found that traces of monomer and solvents often contaminate the product, however. This raises questions regarding their stability and potential hazard. Omitted from Table 5 are numerous chemicals not generally considered hazardous. For example, calcium chloride, which serves as an accelerator in the cementing process (Table 2), is considered a nuisance dust. However, exposure to dust and consequent inhalation or skin and eye contact can produce irritation, usually of the skin, eyes, and airways. For many of the agents listed in Tables 1-4, dermatitis is a common response to skin contact and has not been noted separately in Table 5. Additive irritation is a common occurrence where such materials are used (Mooser, 1987). Knowledge of the practices of handling at the well site, circumstances for storage and disposal, laboratory facilities for washing and changing contaminated clothing and procedures for handling spills are important practical considerations in assessing exposure levels. Evaluation of exposure levels for workers currently handling these agents is beyond the scope of this review. Information concerning occupational practices would provide insight into possible exposure levels on the job site and likely routes of exposure to the agents. Runion (1988), in listing principal health hazards from chemical and physical agents in the petroleum industry, indicated that no data were available on exposures by inhalation or through the skin for those working in the drilling process of the industry. Table 8 presents useful sources of information for the rapid assessment of chemicals encountered in industry.
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TABLE 4 Types of agents, their functions and particular chemicals used in production1 Operation
Type of Agent
Function
Chemical
Collection into system and flow maintenance
1. Corrosion inhibitors
Prevent metal corrosion in presence of water by H,S and/ or CO,
- See Table 1 -
2. Scale inhibitors Prevent or minimize deposition of scale from water due to instability through temperature or pressure change
phosphorous compounds
References
Parker, 1983
- inorganic poly-
phosphates - organic phosphate esters - organic phosphonates - organic amino-
phosphates - organic polymers
ethylenediamine tetraacetic acid (EDTA)Z 3. Wax deposit inhibitors
Prevent wax deposition as crystals in pipe walls, valves, etc .
polymers - linear with branched
Parker, 1983 Gilby, 1983
side chains - copolymer alkylacrylate
and ethylenevinyl acetate
4.Fluidity
Maintain flow
improvers Oil/gas/ water separation
1. Defoamers
2. Demulsifiers
carboxymethyl cellulose copolymers of ethylene and vinylacetate
Parker, 1983 Gilby, 1983
- See Table 1 -
Inhibit or break emulsions
ethoxylated-propylated adducts
Parker, 1983
ethoxylated phenolic resin cationic type quaternary ammonium salts Crude oil pumping and separating
1. wax inhibitors
- See above (Table 4) -
2. Corrosion inhibitors
- See Tables 1 and 2 -
3. Friction reducers
Improve and maintain water soluble polymers Parker, 1983 flow e.g. guar gum, carboxymethyl cellulose ~
lProduction involves the handling of all produced and injected fluids from wellhead to point of disposal, i.e., collection into manifold system. *This agent is particularly expensive.
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TABLE 4 (continued) Operation
Type of Agent
Function
Chemical
References ~
Gas production and processing
Produced water
I. Drying
Hydrate reducers
~~
ethylene glycol, methanol
2. Corrosion inhibitors
- See Table 1 -
1. Corrosion and Scale inhibitors
- See Tables 1 62 4 -
2. Biocides
- See Table 1 -
3. Deoil and Dehydratioin (may include Demulsifying)
Treatment of water before final disposal
~
alkyl quaternary ammonium compounds
Parker, 1983
Parker, 1983
pyridinium compounds glycol alum ferric chloride ferrous sulphate
CONCLUSION This review identifies the possibilities for toxic exposures resulting from occupational use of process chemicals in the oil industry. More information on the chemicals used, their toxicity, and practices in the field are necessary before the safety of current practices may be evaluated convincingly. Further, the toxicity of mixtures of such chemicals remains to be evaluated. A particular problem area in the oil and gas industry seems to be the use of process chemicals in drilling. Engineering considerations make it difficult to enclose drilling operations and effective personal protection is often impractical under field conditions. The degree of protection must be balanced against the magnitude of the hazard in the field. In the past, the degree of hazard has been unknown and appropriate decisions could not be made.
Consideration may be given to seeking substitution or limiting the use of those agents which are well recognized to be hazardous. Where substitution would be extremely difficult, consideration should be given to reducing exposure levels through personal protection. Information based on suitable testing of alternative process chemicals for use in the oil industry are needed in order to effectively assess the potential toxicological nature of process agents and to ensure safety in substitution and the introduction of new chemicals in the future.
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TABLE 5 Process chemicals known to be toxic Type of Agent Chemical Biocidesl Bactericidal
Toxicity*
References
chlorine or chlorine releasers irritant, mild to severe - chlorine - sodium hypochlorite - chloramines - chlorinated guanidines - chlorinated tripotassium - phosphate (odophors)
phenolics
hepato- and nephrotoxicity
Sittig, 1985
- dichloroxylenol - benzyl cresol
organometallics
neurotoxic
- compounds of copper, tin
mercury oxidants - peroxide
aldehydes formaldehyde - paraformaldehyde - glutaraldehyde
irritant, probable carcinogen
quaternary ammonium compounds
suspected embryotoxic effects
Palmer et al., 1983
ethylene glycol
nephrotoxic male reproductive systems
Sittig, 1985 Kalf et al., 1987
-
Dispersants
diesel fuel
altered immunity
carcinogenic?
fluorocarbon solvents (organic) Drying Agents
Sittig, 1985 numerous references: Nizami, 1981 Blair et al., 1986 Thrasher et al., 1987
Rothman & Emmett, 1988 Albrecht & Bryant, 1987
some mutagenic some neurotoxic
ethylene glycol
Kalf et al., 1987 Rothman & Emmett, 1988 [see above]
nephrotoxic male reproductive system methanol
neurotoxic
Weighting Agents
lead sulphide powder
low toxicity in relation to other sulphur-containing problems
Viscosifiers
asbestos
concentration and physical nature of fibre would be a factor
Sittig, 1985 Hanenson, 1980 Ashford, 4987
~ _ _ _ _ _ _ _ _ ~ -
* Many of the agents listed in Tab6 4 as well as here also cause a mild dermatitis, which is not noted separately. Moreover, low level chemical exposure and its subtle effects are difficult to diagnose. (Kadushin, 1986)
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TABLE 5 (continued) Type of Agent Chemical
Toxicity*
Commodity
sodium hydroxide
Surfactants
ethanolamines
nose, eye, and skin irritation, liver, kidney and respiratory disease complications
quaternary ammonium compounds
(see above under Biocides)
References
irritant, burns Mallett et al., 1984
* Many of the agents listed in Table 4 as well as here also cause a mild dermatitis, which is not noted separately. Moreover, low level chemical exposure and its subtle effects are difficult to diagnose. (Kadushin, 1986)
TABLE 6 Process chemicals of potential toxicity Type of Agent Chemical
Comment
Viscosifiers
clays
presence of free silica poses a problem
Corrosion Inhibitors
long-carbon chain imidazolines some implication of chronic toxicity (sometimes reacted with ethylene oxide to yield polyoxyethylene)
Tandon et al., 1984
Clay Stabilizers
zirconium oxychloride
Delongeas et al., 1983
hydroxyalumina
dust and fumes associated with mild occupational dermatitis; zircon granulomas reported; complaints of vertigo, sweet taste in mouth; some cerebral and pulmonary disorders reported some respiratory effects
Scale Inhibitors
EDTA
Deoil and Dehydration Agents
pyridinium compounds
burning of oily flocculation in incinerators a common practice that may yield toxic fumes of SO, and NO,
alum (aluminum sulfate)
- nose and throat irritation
References
Sax, 1984
NOSH, 1984 Tandon et al., 1984
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Sax, 1984
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TABLE 7 Process chemicals of unknown toxicity Type of Agent
Chemical
Comment
References
Viscosifiers
polyacrylamides
*
Darby, 1987
polyacrylate
* *
Darby et al., 1978
copolymer of vinylacetate and malic anhydride Fluid Loss
amides
* ** **
dimethyl silicone
**
polyacrylates carboxymethyl cellulose
Corrosion Inhibitors Defoamers Wax Deposition Inhibitors Demulsifiers
copolymer of alkylacrylate and ethylenevinylacetate
ethoxylated phenolic resin
* **
* Although the parent compounds for such polymers may be toxic (even of high toxicity) polymers in general exhibit low or unrecognized toxicity. (For various polymers ** may also apply.) ** Searches carried out to date have yielded inadequate data (this may be because testing has been inadequate).
TABLE 8 Reliable Sources of Information on Toxicology of Chemicals Used in Industry Telephone Numbers Alberta Occupational Health and Safety, Occupational Health and Safety Library, 10709 Jasper Ave., Edmonton, Alberta T5J 3N3. Provides information to Alberta residents and employers (403 427-3567). Alberta Disaster Services Dangerous Goods Control Division, Compliance Information Centre. Provides information needed by companies or individuals hauling hazardous materials in Alberta (403 422-9600 Edmonton, 1-800-272-9600 elsewhere). Canutech, Transport Canada, Dangerous Goods Branch. Provides information and assistance on transportation incidents in Canada; call collect (613 992-4624). Toxicology Information Response Center, Oak Ridge National Laboratory. Provides information on hazardous substances to physicians, lawyers, and other users on a fee-forservice basis (615 576-1743). Canadian Centre for Occupational Safety and Health. Provides literature searches and data summaries on toxic substances; may not be suitable on an urgent basis (416 523-2981). Reference Works Clayton, G.D., Clayton, F.E. (eds.). Patty’s Industrial Hygiene and Toxicology ed. 3. New York, John Wiley and Sons, 1982, in three volumes. An exceedingly detailed compendium describing industrial processes and hazards, available in reference libraries and in the offices of many large corporations and consulting services.
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TABLE 8 (continued) Doull, J., Klausen, C., Amdur, M. (eds.). Casarett and Doull’s Toxicology, ed. 3. New York, MacMillan 1980. A useful textbook and reference book in toxicology. Finkel, A.J., Hamilton and Hardy’s Industrial Toxicology, ed. 4. Littleton, Massachusetts, John Wright-PSG, 1982. A standard reference in toxicology. Olishifski, J.B. (ed.): Fundamentals of Industrial Hygiene, ed. 2. Chicago, National Safety Council, 1979. An excellent reference in industrial hygiene easily understood by the nonengineer; extensive bibliographies and a supplementon toxic substances makes this a convenient source in an emergency. Parmeggiani, L. (ed.): Encyclopaedia of Occupational Health and Safety, ed. 3. Geneva, International Labour Organization, 1983. A comprehensive source of information on occupational health which is also a useful guide in hazardous materials incidents. Proctor, N.H., Hughes, J.P.: Chemical Hazards of the Workplace. Philadelphia, J.B. Lippincott, 1978. Strongly recommended; an excellent and convenient source. Sax, N.I.: Dangerous Properties of Industrial Materials, ed. 6. New York, Van Nostrand, 1984. An invaluable, comprehensive, and definitive reference. U. S . National Institute for Occupational Safety and Health Administration: Occupational Health Guidelines for Chemical Hazards. Washington, DC, U.S. Government Printing Office, 1981. DHHS (NIOSH) Publication No. 81-123. Useful and inexpensive, but cannot be used alone; guidelines for many common and important hazards are omitted because of U.S. federal standards review.
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DARBY, T.D., JOHNSON, H.J. and NORTHUP, S.J. (1978). An evaluation of apolyurethane for use as a medical grade plastic. Toxicol. App. Pharmacol. 46:449-453. DARBY, T.D. (1987). Safety evaluation of polymer materials. Ann. Rev. Pharmacol. Toxicol. 27:156-1 67. DELONGEAS, J.L., BURNEL, D. and NETTER, P. et al. (1983). Toxicity et pharmacocinetique de l’oxychlorue de zirconium chez la souris et chez le rat. J. Pharmacol. (France) 14(4):437447. DIVINE, B.J. and BARRON, V. (1986). Texaco Mortality Study: II. Patterns of mortality among white males by specific job groups. Am. J. Indust. Med. 10:371-381. DIVINE, B.J. and BARRON, V. (1987). Texaco Mortality Study: III. A cohort study of producing and pipeline workers. Am. J. Indust. Med. 11:189-202. GILBY, G.W. (1983). The use of ethylene-vinyl acetate copolymers as flow improvers and wax deposition inhibitors in waxy crude oil. In: Chemicals in the Oil Industry (Ogden, P.H., ed.). The Royal Society of Chemistry, London. GUIDOTTI, T.L. (10 July 1986). Feasibility and Optimal Design of an Occupational Health Study of Workers in the Gas and Thermal Power Industries in Alberta. Edmonton, Report to the Acid Deposition Research Program of Alberta. GUIDOTTI, T.L. and COTTLE, M.K.W. (1987). Methodological issues in evaluating the health effects of exposure to acid-forming emissions. In: Proceedings of the Second Symposiudworkshop on Acid Forming Emissions in Alberta and their Ecological Effects (Calgary, 12-15 May 1986). Acid Deposition Research Program, pp. 359-389, Calgary. HANENSON, I.B. (ed.). (1980). Quick Reference to Clinical Toxicology. J.B. Lippincott Co., Philadelphia. HANIS, W.M., HOLMES, T.M., SHALLENBERGER, L.G. and JONES, K.E. (1982). Epidemiologic study of refinery and chemical plant workers. J. Occup. Med. 24:203-212. HOAR, S.K., BLAIR, A.A. and HOMES, F.F. et al. (1986). Agricultural herbicide use and risk of lymphoma and soft-tissue. JAMA 256:1141-1 147. KADUSHIN, F. [as reported by McCann, B.]. (July 22, 1986). Effect of low-level chemical exposure hard to diagnose. The Medical Post. KALF, G.F., POST, G.B. and SNYDER, R. (1987). Solvent Toxicology: Recent advances in the toxicology of benzene, the glycol ethers, and carbon tetrachloride. Ann. Rev. Pharmacol. Toxicol. 27:399427. KELLEY, J.A. (1983). The Chemistry of Corrosion Inhibitors Used in Oil Production. In: Chemicals in the Oil Industry (Ogden, P.H., ed.). The Royal Society of Chemistry, London. LABOUR CANADA. (April 1985). Workplace Hazardous Materials Information System (WHMIS). Report of the Project Steering Committee. (Labour Canada, Cat. No. L46-1568/ 85E), Ottawa. MALLETT, A.K., WISE, A. and ROWLAND, J.R. (1984). Hydrocolloid food additives and rat caecal microbial enzyme activities. Food Chem. Toxicol. (England) 22(6):415-418. MILLS, P.K., NEWELL, G.R. and JOHNSON, D.E. (1984). Testicular cancer associated with employment in agriculture and oil and natural gas extraction. Lancet 1:207-210. MOOSER, S.B. (1987). The epidemiology of multiple chemical sensitivities (MCS). Occup. Med. : State of the Art Reviews 2:663-668. NANGLE, B.J. (March, 1988). Chemical Hazards in the WorkplaceAssessment, Communication and Interpretation of Information Advice from a Manufacturer. Dept. of Labour, Occ. Health and Safety Newsletter #40.
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NIOSH. (198 1). Occupational Health Guidelines for Chemical Hazards. U.S. Government Printing Office, Washington, DC. (DHHS Pub. No. [NIOSH] 81-123). NIOSH. (1984). Registry of Toxic Effects of Chemical Substances (1983 Supplement to 198182). U. S. Government Printing Offices, Washington, DC. NIZAM, R.M. (1981). Formaldehyde: Its hazards at work and in the home. Modem Med. Canada 36: 1007. OGDEN, P.H. (ed.). (1983). Chemicals in the Oil Industry. The Royal Society of Chemistry, London. OILWEEK GUIDE TO DRILLING FLUIDS. (1986, 1987, 1988). Annual Supplement to December Issue of Oilweek, a Maclean Hunter Publication. PALMER, A.K., BOTTOMLEY, A.M., EDWARDS, J.A. and CLARK, R. (1983). Absence of embryotoxic effects in rats with three quaternary ammonium compounds (Cationic Surfactants). Toxicol. (Ireland) 26(34):3 13-3 15. PARKER, R.C. (1983). Chemicals in the Oil Industry (Ogden, P.H., ed.). The Royal Society of Chemistry, London. RIEKE, H.H. and CHILINGARIAN, G.V. (1981). Drilling and Drilling Fluids (Chilingarian, G.V. and Vorabutr, P., ed.). Amsterdam, Elsevier. ROTHMAN, N. and EMMETT, E.A. (1988). The carcinogenicpotential of selected petroleumderived products. Occup. Med.: State of the Art Reviews 3:475494. RUNION, H.E. (1988). Occupational exposures to potentially hazardous agents in the petroleum industry. Occup. Med.: State of the Art Reviews 3:431444. SAX, N.I. (ed.). (1984). Dangerous Properties of Industrial Materials. 6th Edition. Van Nostrand, Reinhold, New York. SHAW, D.R. (1974). Proc. 8th Canadian Symp. Water Poll. Res. Canada, pp. 315-319. SITTIG, M. (1985). Handbook of Toxic and Hazardous Chemicals and Carcinogens. 2nd Edition. Noyes, Park Ridge, NJ. TANDON, S.K., JAIN, V.K. and MATHURS, A.K. (1984). Effect of metal chelators on excretion and tissue levels of essential trace elements. Environmental Research 35( 1):237-245. THOMAS, T.L., STEWART, P.A., STEMHAGEN, A., CORREA, P., NORMAN, S.A., BLEEKER, M.L. and HOOVER, R.N. (1987). Risk of astrocytic brain tumors associated with occupational chemical exposures. A case-referent study. Scand. J. Work Environ. Health 13:417423. THRASHER, J.D., WOJDANI, A., CHEUNG, G. and HEUSER, G. (1987). Evidence for formaldehyde antibodies and altered cellular immunity in subjects exposed to formaldehyde in mobile homes. Arch. Env. Health 42:347-350. WEN, C.P., TSAI, S.P., McCLELLAN, W.A. and GIBSON, R.L. (1983). Long-term mortality study of oil refinery workers. I. Mortality of hourly and salaried workers. Am. J. Epidemiol. 118:526-542.
Received April 10, 1989 Accepted August 5, 1989
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Process Chemicals in the Oil and Gas Industry: Potential Occupational Hazards Merva K.W. Cottle and Tee L. Guidotti Toxicol Ind Health 1990 6: 41 DOI: 10.1177/074823379000600104 The online version of this article can be found at: http://tih.sagepub.com/content/6/1/41
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PROCESS CHEMICALS IN THE OIL AND GAS INDUSTRY: POTENTIAL OCCUPATIONAL HAZARDS MERVA K. W. COTTLE, PH.D. AND TEE L. GUIDOTTI, M.D. Occupational Health Program University of Alberta Faculty of Medicine 13-103 Clinical Sciences Bldg. Edmonton, Alberta T6G 2G3 Canada
Numerous chemicals are used in various processes of the oil and gas industry: drilling, cementing, completion, stimulation, and production. The number and the complexity of composition of process chemicals has increased greatly over the last three decades. The occupational hazards of exposure to these agents has received little attention. We reviewed the various processes in the industry, the type of chemicals used in each process, and some of their characteristics. We placed emphasis on those for which signijicant toxicity has been established or is suspected, and those for which there is incomplete information on their chemistry and health hazards. This report is intended to form a basis for a more complete survey of the process chemicals, and to draw attention to the possibilities for toxic exposure resulting from use of these agents in the oil and gas industry. The ultimate objective is to promote the safe use of these agents in the industry. During a study on the feasibility of a proposed occupational health study of workers in the gas industry in Alberta, we identified a need to examine and identify agents used in the oil and gas industry that could produce toxic effects with occupational exposure (Guidotti, 1986). “Process” or “production” chemicals used in the oil production industry number in the hundreds (Parker, 1983). They are used in the various processes necessary to the extraction of oil and gas resources: drilling, cementing, completion, stimulation and production; and are mostly specialty chemicals produced for the industry and marketed under trade names. Often, these chemicals are encountered only rarely outside the oil and gas industry. To ensure that these valuable chemicals are used safely, it is desirable to evaluate the potential hazard they may present. 1. Address correspondence to: Dr. Tee L. Guidotti. Occupational Health Program, University of Alberta Faculty of Medicine, 13-103 Clinical Sciences Bldg., Edmonton, Alberta T6G 2G3, Canada. 2. This paper was presented at the XVI Medichem International Congress on Occupational Health in the Chemical Industry, Helsinki, 1988. 3. Supported by the Tripartite Fund for Occupational Health and by the Acid Deposition Research Program of Alberta. Toxicology and Industrial Health, 6:1, pp. 41-56 Copyright 0 1990 Princeton Scientific Publishing Co., Inc. ISSN: 0748-2337
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In this paper, the term “process chemicals” will be used rather than “production chemicals” because the term “production” has a specific meaning within the oil industry, implying the sustained productivity of a well. This is only one part of the life cycle of a well, although the most important part if the well is successful. From the occupational health point of view, however, the other steps in well development are of equal or even greater interest. Compared to life-threatening occupational risks in the industry, such as that of a “knockdown” by hydrogen sulphide, the occupational hazards of process chemicals might appear to be of minor concern. However, some of these chemicals are known to have toxic properties and others have the potential for significant toxicity. Knowledge of their chemical nature and contaminants, particularly in preparations of commercial grade, is incomplete for many process chemicals. Moreover, mixtures which result from the simultaneous use of the process chemicals raise questions concerning the combined toxicity of the mixtures or products of reaction. We have reviewed specific chemicals available to the oil and gas industry in Alberta. We emphasize those with potential or established toxicity and those for which there is evidence of a potential occupational hazard. Because of the limited available knowledge of the chemistry of some of the products, this survey is not complete. It is intended to form the basis for developing a more complete toxicological profile of the process chemicals and to stimulate further investigation. We hope that further scrutiny and identification of “problem chemicals’’ may lead to a rational basis for making recommendations on exposure limits, use of protective equipment, alteration in the pattern of usage, and the substitution of less desirable products with safer materials. This report does not provide detailed toxicological information on the individual agents or classes of agents but directs the reader to useful reviews and recent reports on their toxicity.
BACKGROUND The use of chemicals in the oil industry to enhance recovery and production has increased since the 1930’s, when their usefulness was first recognized. The number of specialty chemicals available to the industry has increased greatly in the decades since. A large number of chemical agents are used. These range from complex organic polymers, for which the chemical structure is incompletely understood, to relatively simple inorganic compounds. Complex polymers have tended to replace some of the natural clays previously used. In addition to the primary agents of concern, there is the possibility that chemicals of commercial grade may contain contaminants. Others may be altered in the process itself, through chemical reaction and heat, resulting in complex secondary mixtures. For example, drilling mud and the other materials which ultimately are drained into the sump on the drilling site contain a myriad of chemicals.
A major difficulty in surveying the potential toxicity of process chemicals is the use of the trade names and limited information on the chemical constituents. With the intro-
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duction of the Workplace Hazardous Materials Information System (WHMIS) in Canada (Labour Canada, 1985), this information should become more accessible. Process chemicals used in the oil and gas industry have been categorized according to the various processes in which they find a purpose: drilling, cementing, completion, stimulation and production. Data on the chemicals is not easy to come by. General information on the chemicals used in water-based drilling has been obtained chiefly from the proceedings of a symposium organized by the Northwest Region of the Industrial Division of the Royal Society of Chemistry and edited by Ogden (1983). A number of these papers, specifically those of Bensted et al.; Gilby; Kelley; and Parker provide background on the general classes of chemicals (and in some cases more specific agents) used in the oil industry. A useful source of information on the use of specific chemicals found in Alberta is Oilweek, the industry journal (1986, 1987 & 1988). Runion (1988) listed substances that may be present in refining and allied petrochemical operations. Information available on these specific agents is in Tables 1 to 4, which should be regarded only as an initial survey, in time to be followed by an intensive and more detailed survey of the specific chemicals used. Guidotti (1986) included a brief survey of the process chemicals and their potential hazards in a study on the feasibility of occupational health studies in the industry in Alberta. Guidotti and Cottle (1986) discussed the issue in a scientific report based on this work. Divine and Barron (1987) indicated that formaldehyde, asbestos and mercury are hazardous exposures for pipeline and production workers. Runion (1988), in providing detailed information on health hazards in the petroleum industry, mentioned liquid or particulate additives to drilling mud as health hazards for petroleum industry drillers. Runion (1988) also surveyed the types of agents used in water-based drilling and production; and organized these based upon the processes involved.
PROCESSES Drilling fluid or ‘mud’ serves to circulate and to remove drilled cuttings from the base
of the bored hole, in order to maintain the stability of the hole and to cool the bit. The drilling mud may include liquids, solids, and even gases. Because of the explosive nature of gases under pressure, they are avoided as additives. Water-based mud consists of a liquid colloid, containing both inert and chemically reactive ingredients. Drilling chemicals are used to prepare and maintain drilling mud appropriate to the requirements of the site and may be classified according to use: weighting agents, viscosifiers, dispersants, fluid loss additives, commodity chemicals, biocides, corrosion inhibitors, surfactants and defoamers (Table 1). Cementing prevents borehole collapse, provides a base for drilling deeper, and may also serve to isolate non-producing from producing portions of the bore. Portland cement is used, with additives depending on the requirement. These are also classified by use: weighting agents, lost circulation materials (including accelerators and retarders of the cement-setting process), fluid loss additives, dispersants, and other additives (Table 2).
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TABLE 1 Process chemicals used in water-based drilling172 Type of Agent
Function
1. Weighting agents Provide optimal density 2. Viscosifiers
Provide fluid viscosity
Chemical
References
barytes (iron oxides) calcium carbonate lead sulphide powder
Parker, 1983 Oilweek, 1988
clays - bentonite - attapulgite
polymers
Parker, 1983
- polyacrylate - polyacrilamide - carbohydrate bipolymer - cellulose ethers (methyl, ethyl,
Oilweek, 1988
benzyl hydroxylethyl) - copolymer of vinyl acetate and maleic anhydride xanthum gum asbestos - shredded - pelletized
3. Dispensants (Thinners)
Dispense solid particles
complex organic compounds - lignite (mineral of the coal
series with complex organic acids often in the form of ferric/ferrochromeor chromefree lignosulphonates, might be considered polymers in chemical characteristics) - quebracho (crude tannic acid originating from Quercus, the oak tree)
Divine & Barron, 1987 Oilweek, 1988 Parker, 1983 Bensted et al., 1983 Oilweek, 1988
solvents - ethylene glycol and monobutyl
ether
- lecithin in diesel fuel (T.N. Biosperse3) - liquid organic thinner (T.N. Tackle3) - water solution of fluorocarbon (T.N. D-5g3)
Divine & Barron, 1987 Runion, 1988
polymers - polyacrylates Drilling mud functions to circulate and remove drilled cuttings, maintain stability of the bore hole, and cool the bit and tubing. *Herbicides are used in the vicinity of the well-site to limit vegetation growth but are not unique to the oil and gas industry. Trade name.
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TABLE 1 (continued) Type of Agent
Function
4.Fluidloss
Prevent loss of fluid from drilling mud
additives
Chemical
References
polymers
Parker, 1983
- polyacrylates - carboxymethyl cellulose
gums - xanthan - guar
pregelatinized starch and lignite asphalt
Oilweek, 1988
shredded cedar fibres 5 . Commodity chemicals
- Adjustment to
6. Biocidesl Bacteriostats
- Inhibit growth of
optimal pH micro-organisms such as: slimeproducing; iron bacteria, yeasts, filamentous fungi and sulphate reducing bacteria which may have serious effects by production of H2S
lime sodium hydroxide
Parker, 1988
chlorine or chlorine releasors e.g. chlorine, sodium hypochlorite, chloramines, chlorinated quanidines, chlorinated tripotassium tripotassium phosphate
Parker, 1983 Bessems and Clemmit, 1983
Oilweek, 1988
phenols - dichloroxylenol - benzyl cresol
organometallics - compounds of copper, tin and
Divine & Barron, 1987
mercury oxidants - peroxide
aldehydes
- formaldehyde - gluteraldehyde - paraformaldehyde
quaternary ammonium compounds - trimethylalkyl ammonium chloride
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TABLE 1 (continued) Type of Agent
Function
Chemical
References
7 . Corrosion inhibitors
Prevent or inhibit metal corrosion occurring in the presence of water by H,S and CO,
primary/polysubstituted monoamines and polyamines amides long-chain aliphatic diamines, long-carbon-chain imidazolines (sometimes reacted with ethylene oxide to yield poly oxyethylene) organic sulphophosphate (inhibits oxygen corrosion)
Parker, 1983 Kelley, 1983
quaternary ammonium compounds (trimethylalkyl) 8. Surfactants
Prevent formation of emulsions or precipitates
sulphonates
Parker, 1983
ethanolamines (mono & di) quaternary ammonium compounds
9. Defoamers
Deactivate surface active compounds in crude oil (entrapped gas is released)
phosphate esters (metallic soaps of fatty acids)
Parker, 1983
organic silicone compounds (dimethyl silicone)
CompletionlStimulation is the final drilling step in preparing a new well for production. Completion generally involves cleaning the drilled hole and possibly providing better communication with other layers of rocks in order to improve the flow of production. Stimulation usually involves acidising and hydraulic fracturing of the rock strata. Stimulation also improves productivity and may be important especially if drilling has damaged the rocks or if the rock is of poor quality. Acidising also entails the use of corrosion inhibitors, surfactants, chelating agents, fluid loss agents, clay stabilizers and polymers (Table 3). Production refers to the handling of all produced (pumped) and injected fluids, from the wellhead to the point of dispersal. This includes collection from individual wellheads into a common manifold system, oil/gas/water separation, and crude oil pumping and separating. Table 4 presents the typical chemicals that are used for a number of specific purposes, largely to maintain flow in this system. These include inhibitors of corrosion, scale, and wax formation. In addition, a score of processing chemicals are
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TABLE 2 Process chemicals used in cementing' Type of Agent
Function
Chemical
1. Weighting agents
- See Table 1 -
2. Fluidloss additives
- See Table 1 -
References
3. Lost circulation materials
Prevent loss of cement slurry to the formation
gilsonite mica
Parker, 1983
4. Accelerators
Speed up cement setting time
calcium chloride sodium silicate
Parker, 1983
5. Retarders
Extend cement setting time to allow cement pumping in deep wells
calcium lignosulphonate gums starches carboxymethylhydroxyethyl cellulose
Bensted et al., 1983 Parker, 1983
6. Dispersants and friction reducers
Improve flow or rheology of cement slurry
lignosulphonates
Parker, 1983
lignins polymers acrylamides
-
naphthalene condensation products aryl alkyl sulphonates I Cementing seals casing into boreholes prevents its collapse, provides a base to drill deeper and isolates producing from non-producing portions.
used in production to facilitate dehydration, defoaming, fluidity and startability of waxy crudes, and friction reduction. Deoiling of water, inhibition of bacterial activity (biocides), and deposition of gas hydrates and sulphur are also important aspects of maintaining production.
TOXICITY OF PROCESS CHEMICALS Many of the classes of agents used in all processes contain chemicals well recognized as toxic. There are also many of unknown toxicity and many for which their complete chemical composition, and therefore their possible toxicity, is not known. Those agents for which toxicity is known, suspected, or unknown due to uncertainty over composition are presented in Tables 5, 6 and 7, respectively. It is evident from Table 5 that the agents of most consistently documented toxicity are the biocides (used in drilling and production), the dispersants (used in drilling and cementing) and the drying agents (used in production). Many process chemicals fall into
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TABLE 3 Process chemicals used in completion and stimulation' Type of Agent
Function
Chemical
1. Viscosifiers
Reduce pressure losses due to friction while pumping
- See Table 1 -
2. Fluid loss additives
- See Table 1 -
3. Surfactants
- See Table 1 -
4.Clay stabilizers
Prevent or minimize clay hydration
potassium chloride
References
Parker, 1983
hydroxyalumina zirconium oxychloride
Completion and stimulation serve to clean drilled hole and improve quality and productivity.
the group of suspected toxicity, in Table 6. More information concerning toxicity is needed for these agents. Although the parent compounds used in preparing polymers (Table 7) may be toxic (some highly toxic), polymers, in general, exhibit low toxicity. A recent paper (Darby, 1987) on the safety of polymers found that traces of monomer and solvents often contaminate the product, however. This raises questions regarding their stability and potential hazard. Omitted from Table 5 are numerous chemicals not generally considered hazardous. For example, calcium chloride, which serves as an accelerator in the cementing process (Table 2), is considered a nuisance dust. However, exposure to dust and consequent inhalation or skin and eye contact can produce irritation, usually of the skin, eyes, and airways. For many of the agents listed in Tables 1-4, dermatitis is a common response to skin contact and has not been noted separately in Table 5. Additive irritation is a common occurrence where such materials are used (Mooser, 1987). Knowledge of the practices of handling at the well site, circumstances for storage and disposal, laboratory facilities for washing and changing contaminated clothing and procedures for handling spills are important practical considerations in assessing exposure levels. Evaluation of exposure levels for workers currently handling these agents is beyond the scope of this review. Information concerning occupational practices would provide insight into possible exposure levels on the job site and likely routes of exposure to the agents. Runion (1988), in listing principal health hazards from chemical and physical agents in the petroleum industry, indicated that no data were available on exposures by inhalation or through the skin for those working in the drilling process of the industry. Table 8 presents useful sources of information for the rapid assessment of chemicals encountered in industry.
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TABLE 4 Types of agents, their functions and particular chemicals used in production1 Operation
Type of Agent
Function
Chemical
Collection into system and flow maintenance
1. Corrosion inhibitors
Prevent metal corrosion in presence of water by H,S and/ or CO,
- See Table 1 -
2. Scale inhibitors Prevent or minimize deposition of scale from water due to instability through temperature or pressure change
phosphorous compounds
References
Parker, 1983
- inorganic poly-
phosphates - organic phosphate esters - organic phosphonates - organic amino-
phosphates - organic polymers
ethylenediamine tetraacetic acid (EDTA)Z 3. Wax deposit inhibitors
Prevent wax deposition as crystals in pipe walls, valves, etc .
polymers - linear with branched
Parker, 1983 Gilby, 1983
side chains - copolymer alkylacrylate
and ethylenevinyl acetate
4.Fluidity
Maintain flow
improvers Oil/gas/ water separation
1. Defoamers
2. Demulsifiers
carboxymethyl cellulose copolymers of ethylene and vinylacetate
Parker, 1983 Gilby, 1983
- See Table 1 -
Inhibit or break emulsions
ethoxylated-propylated adducts
Parker, 1983
ethoxylated phenolic resin cationic type quaternary ammonium salts Crude oil pumping and separating
1. wax inhibitors
- See above (Table 4) -
2. Corrosion inhibitors
- See Tables 1 and 2 -
3. Friction reducers
Improve and maintain water soluble polymers Parker, 1983 flow e.g. guar gum, carboxymethyl cellulose ~
lProduction involves the handling of all produced and injected fluids from wellhead to point of disposal, i.e., collection into manifold system. *This agent is particularly expensive.
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TABLE 4 (continued) Operation
Type of Agent
Function
Chemical
References ~
Gas production and processing
Produced water
I. Drying
Hydrate reducers
~~
ethylene glycol, methanol
2. Corrosion inhibitors
- See Table 1 -
1. Corrosion and Scale inhibitors
- See Tables 1 62 4 -
2. Biocides
- See Table 1 -
3. Deoil and Dehydratioin (may include Demulsifying)
Treatment of water before final disposal
~
alkyl quaternary ammonium compounds
Parker, 1983
Parker, 1983
pyridinium compounds glycol alum ferric chloride ferrous sulphate
CONCLUSION This review identifies the possibilities for toxic exposures resulting from occupational use of process chemicals in the oil industry. More information on the chemicals used, their toxicity, and practices in the field are necessary before the safety of current practices may be evaluated convincingly. Further, the toxicity of mixtures of such chemicals remains to be evaluated. A particular problem area in the oil and gas industry seems to be the use of process chemicals in drilling. Engineering considerations make it difficult to enclose drilling operations and effective personal protection is often impractical under field conditions. The degree of protection must be balanced against the magnitude of the hazard in the field. In the past, the degree of hazard has been unknown and appropriate decisions could not be made.
Consideration may be given to seeking substitution or limiting the use of those agents which are well recognized to be hazardous. Where substitution would be extremely difficult, consideration should be given to reducing exposure levels through personal protection. Information based on suitable testing of alternative process chemicals for use in the oil industry are needed in order to effectively assess the potential toxicological nature of process agents and to ensure safety in substitution and the introduction of new chemicals in the future.
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TABLE 5 Process chemicals known to be toxic Type of Agent Chemical Biocidesl Bactericidal
Toxicity*
References
chlorine or chlorine releasers irritant, mild to severe - chlorine - sodium hypochlorite - chloramines - chlorinated guanidines - chlorinated tripotassium - phosphate (odophors)
phenolics
hepato- and nephrotoxicity
Sittig, 1985
- dichloroxylenol - benzyl cresol
organometallics
neurotoxic
- compounds of copper, tin
mercury oxidants - peroxide
aldehydes formaldehyde - paraformaldehyde - glutaraldehyde
irritant, probable carcinogen
quaternary ammonium compounds
suspected embryotoxic effects
Palmer et al., 1983
ethylene glycol
nephrotoxic male reproductive systems
Sittig, 1985 Kalf et al., 1987
-
Dispersants
diesel fuel
altered immunity
carcinogenic?
fluorocarbon solvents (organic) Drying Agents
Sittig, 1985 numerous references: Nizami, 1981 Blair et al., 1986 Thrasher et al., 1987
Rothman & Emmett, 1988 Albrecht & Bryant, 1987
some mutagenic some neurotoxic
ethylene glycol
Kalf et al., 1987 Rothman & Emmett, 1988 [see above]
nephrotoxic male reproductive system methanol
neurotoxic
Weighting Agents
lead sulphide powder
low toxicity in relation to other sulphur-containing problems
Viscosifiers
asbestos
concentration and physical nature of fibre would be a factor
Sittig, 1985 Hanenson, 1980 Ashford, 4987
~ _ _ _ _ _ _ _ _ ~ -
* Many of the agents listed in Tab6 4 as well as here also cause a mild dermatitis, which is not noted separately. Moreover, low level chemical exposure and its subtle effects are difficult to diagnose. (Kadushin, 1986)
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TABLE 5 (continued) Type of Agent Chemical
Toxicity*
Commodity
sodium hydroxide
Surfactants
ethanolamines
nose, eye, and skin irritation, liver, kidney and respiratory disease complications
quaternary ammonium compounds
(see above under Biocides)
References
irritant, burns Mallett et al., 1984
* Many of the agents listed in Table 4 as well as here also cause a mild dermatitis, which is not noted separately. Moreover, low level chemical exposure and its subtle effects are difficult to diagnose. (Kadushin, 1986)
TABLE 6 Process chemicals of potential toxicity Type of Agent Chemical
Comment
Viscosifiers
clays
presence of free silica poses a problem
Corrosion Inhibitors
long-carbon chain imidazolines some implication of chronic toxicity (sometimes reacted with ethylene oxide to yield polyoxyethylene)
Tandon et al., 1984
Clay Stabilizers
zirconium oxychloride
Delongeas et al., 1983
hydroxyalumina
dust and fumes associated with mild occupational dermatitis; zircon granulomas reported; complaints of vertigo, sweet taste in mouth; some cerebral and pulmonary disorders reported some respiratory effects
Scale Inhibitors
EDTA
Deoil and Dehydration Agents
pyridinium compounds
burning of oily flocculation in incinerators a common practice that may yield toxic fumes of SO, and NO,
alum (aluminum sulfate)
- nose and throat irritation
References
Sax, 1984
NOSH, 1984 Tandon et al., 1984
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Sax, 1984
Toxicology and Industrial Health, Vol. 6, No. 1, 1990
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TABLE 7 Process chemicals of unknown toxicity Type of Agent
Chemical
Comment
References
Viscosifiers
polyacrylamides
*
Darby, 1987
polyacrylate
* *
Darby et al., 1978
copolymer of vinylacetate and malic anhydride Fluid Loss
amides
* ** **
dimethyl silicone
**
polyacrylates carboxymethyl cellulose
Corrosion Inhibitors Defoamers Wax Deposition Inhibitors Demulsifiers
copolymer of alkylacrylate and ethylenevinylacetate
ethoxylated phenolic resin
* **
* Although the parent compounds for such polymers may be toxic (even of high toxicity) polymers in general exhibit low or unrecognized toxicity. (For various polymers ** may also apply.) ** Searches carried out to date have yielded inadequate data (this may be because testing has been inadequate).
TABLE 8 Reliable Sources of Information on Toxicology of Chemicals Used in Industry Telephone Numbers Alberta Occupational Health and Safety, Occupational Health and Safety Library, 10709 Jasper Ave., Edmonton, Alberta T5J 3N3. Provides information to Alberta residents and employers (403 427-3567). Alberta Disaster Services Dangerous Goods Control Division, Compliance Information Centre. Provides information needed by companies or individuals hauling hazardous materials in Alberta (403 422-9600 Edmonton, 1-800-272-9600 elsewhere). Canutech, Transport Canada, Dangerous Goods Branch. Provides information and assistance on transportation incidents in Canada; call collect (613 992-4624). Toxicology Information Response Center, Oak Ridge National Laboratory. Provides information on hazardous substances to physicians, lawyers, and other users on a fee-forservice basis (615 576-1743). Canadian Centre for Occupational Safety and Health. Provides literature searches and data summaries on toxic substances; may not be suitable on an urgent basis (416 523-2981). Reference Works Clayton, G.D., Clayton, F.E. (eds.). Patty’s Industrial Hygiene and Toxicology ed. 3. New York, John Wiley and Sons, 1982, in three volumes. An exceedingly detailed compendium describing industrial processes and hazards, available in reference libraries and in the offices of many large corporations and consulting services.
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TABLE 8 (continued) Doull, J., Klausen, C., Amdur, M. (eds.). Casarett and Doull’s Toxicology, ed. 3. New York, MacMillan 1980. A useful textbook and reference book in toxicology. Finkel, A.J., Hamilton and Hardy’s Industrial Toxicology, ed. 4. Littleton, Massachusetts, John Wright-PSG, 1982. A standard reference in toxicology. Olishifski, J.B. (ed.): Fundamentals of Industrial Hygiene, ed. 2. Chicago, National Safety Council, 1979. An excellent reference in industrial hygiene easily understood by the nonengineer; extensive bibliographies and a supplementon toxic substances makes this a convenient source in an emergency. Parmeggiani, L. (ed.): Encyclopaedia of Occupational Health and Safety, ed. 3. Geneva, International Labour Organization, 1983. A comprehensive source of information on occupational health which is also a useful guide in hazardous materials incidents. Proctor, N.H., Hughes, J.P.: Chemical Hazards of the Workplace. Philadelphia, J.B. Lippincott, 1978. Strongly recommended; an excellent and convenient source. Sax, N.I.: Dangerous Properties of Industrial Materials, ed. 6. New York, Van Nostrand, 1984. An invaluable, comprehensive, and definitive reference. U. S . National Institute for Occupational Safety and Health Administration: Occupational Health Guidelines for Chemical Hazards. Washington, DC, U.S. Government Printing Office, 1981. DHHS (NIOSH) Publication No. 81-123. Useful and inexpensive, but cannot be used alone; guidelines for many common and important hazards are omitted because of U.S. federal standards review.
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Received April 10, 1989 Accepted August 5, 1989
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