ACCESS NUMBER: 30900 

STUDY TITLE: Deepwater Program: Literature Review, Environmental Risks of 

Chemical Products Used in Gulf of Mexico Deepwater Oil & Gas Operations 

REPORT TITLE: Deepwater Program: Literature Review, Environmental Risks of 

Chemical Products Used in Gulf of Mexico Deepwater Oil & Gas Operations, Volume I: 

Technical Report and Volume II: Appendices

CONTRACT NUMBER: 01-98-CT-30900 

SPONSORING OCS REGION: Gulf of Mexico 

APPLICABLE PLANNING AREA: Gulf of Mexico 

FISCAL YEARS OF PROJECT FUNDING: 1998; 1999; 2000; 2001 

COMPLETION DATE OF REPORT: January 2001 

COSTS: FY 1998: $25,553; FY 1999: $93,398; FY 2000: $228,421; FY 2001: $19,935 

PROJECT MANAGER: P. Boehm 

AFFILIATION: Arthur D. Little, Inc. 

ADDRESS: 20 Acorn Park, Cambridge, Massachusetts 00234 

PRINCIPAL INVESTIGATORS: P. Boehm, Dan Caudle, Debbie French, Nancy 

Rabalais, Robert Spies 

KEY WORDS: Gulf of Mexico; deepwater; chemical inventory; chemical storage; 

ecological risk; spill modeling; deepwater biology 

BACKGROUND: Chemicals have been used in offshore Gulf of Mexico (GOM) oil and 

natural gas exploration and production (E&P) since development of the offshore 

resources over a half a century ago. From 1947 to 1985, E&P activities focused on the 

shallow waters of the continental shelf. Since the mid-1980s, however, the pace of 

exploration and development in the deep waters of the GOM has accelerated rapidly. 

By the end of 1999, approximately 1,200 wells had been drilled in water depths 

exceeding 1,000 ft (305 m) (Minerals Management Service, May 2000). Moreover, 

production from these deepwater wells has now surpassed production in shallow water, 

despite the fact that only 4% of all producing fields in the GOM are in deepwater. 

OBJECTIVES: (1) Establish a baseline inventory of the chemical products, 

compounds, and mixtures in current use by operators in the GOM, with emphasis on 

deep waters (over 1,000 ft. or 305 m; (2) estimate the amount of such chemicals 

expected to be used as exploration in the GOM increases, with emphasis on deep 

waters; (3) locate and collect technical information on chemical volumes in typical GOM 

operations; (4) develop conceptual models using a range of chemical spill scenarios 
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and predicted impacts as a result of these spills; (5) develop an inventory of types and 

amounts of hazardous substances stored, handled, transferred to, and used on offshore 

oil and gas facilities in all water depths. 

DESCRIPTION: An inventory of chemicals used in the Gulf of Mexico was compiled 

based on data received from three major energy companies operating in both the 

shallow and deep waters of the Gulf of Mexico, annual reports provided in World Oil

magazine, MSDS sheets, and a review of Hudgins’ 1991 report on chemical usage in 

the North Sea. For each of four chemical classes two tables were developed. The first 

table describes the functional categories within the class and the second lists the 

products within each chemical class. This data set establishes a searchable chemical 

inventory database that includes information on chemical products; chemical handling, 

physical and chemical properties and toxicological data for selected chemicals and/or 

products. 

Models were developed for offshore E&P operations to estimate the volume of chemical 

transported, stored, and expected to be used at any one time in the Gulf of Mexico 

(GOM) as follows: (1) data was provided by three major operators in the GOM and their 

chemical suppliers (total of eight), (2) the data was unitized to yield average volumes or 

concentrations for each operational unit (well or production amount), (3) the unitized 

data were multiplied by the corresponding number of wells or fluid production data to 

extrapolate total volume estimates for the entire GOM. 

A subset of representative chemicals used in the deepwater and shallow water was 

selected for detailed study based on the following criteria: chemicals used offshore in 

high volumes; potential impact on the environment and factors affecting fate and 

transport. A total of 17 spill scenarios was developed and modeled using Applied 

Science Associates’ (ASA) chemical spill model CHEMMAP. Sixteen spill scenarios 

were modeled using shallow water data and one spill scenario was modeled in 

deepwater. The shallow water current data were obtained from measurements made 

by Texas A&M University as part of the LATEX program. For each of the chemicals 

modeled, habitat areas exposed to peak concentrations or mass loadings within range 

intervals were tabulated. These peak exposure concentrations were compared against 

acute toxicity data to estimate the potential impact to the environment. 

SIGNIFICANT CONCLUSIONS: The results of this analysis indicate a potential for 

impact from a release of either zinc bromide or ammonium chloride. The modeled 

impacts for zinc bromide were predicted based on a 45,000 gallon release to the 

environment, a predicted maximum exposure concentration of greater than 1ppm for at 

least one hour in an area of 11 million m2

 (11 km2, volume of 11 million m2 x 114 m 

deep = 1,254 million m3) around the spill site and an acute 48-hr LC50 toxicity threshold 

for Ceriodaphnia dubia (freshwater crustacean) of 0.5 mg/L. While a spill of ammonium 

chloride was not modeled, a review of the chemical’s structure and properties indicate 

that it would behave similarly to potassium chloride. Utilizing the modeled maximum 

predicted exposure concentrations of potassium chloride as a surrogate for ammonium 

chloride resulting from a potential release of 4,700 kg, a comparison with the LC-50 
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marine toxicity threshold of 250 mg/L for Salmo salar (Atlantic salmon) was conducted 

that indicates a positive potential for environmental impact. Since the analysis was 

conducted by proxy, this predication must be qualified as only an indicator of potential 

risk and the need for a more focussed study on the effects of ammonium chloride on the 

marine environment. 

STUDY RESULTS: Chemicals perform critical functions during drilling; cementing; well 

completion, stimulation, and workover processes; and producing processes. In offshore 

operations, chemicals fall naturally into four major classes: (1) drilling fluid chemicals, 

(2) cementing chemicals, (3) completion, stimulation, and workover chemicals and (4) 

Production-treating chemicals. The liquid and solid drilling fluid chemicals used in the 

highest quantity in the GOM are: Shale Control Inhibitors (liquid)– 1,210,000 gal. 

(shallow water); 763,000 gal. (deepwater); Weighting Materials – 326,000,000 lbs. 

(shallow water); 372,000,000 lbs. (deepwater); and Shale Control Inhibitors (solid) – 

6,660,000 lbs. (shallow water); 14,000,000 lbs. (deepwater). The cementing chemicals 

used in the highest quantity in the GOM are: Basic Cements – 203,000,000 lbs. 

(shallow water); 18,500,000 lbs. (deepwater) Silica – 14,100,000 lbs. (shallow water); 

1,780,000 lbs. (deepwater) Extenders/density-reducers – 3,890,000 lbs. (shallow 

water); 365,000 lbs. (deepwater). Except for the chemically inert substances such as 

sand and ceramic proppants the completion, stimulation and workover chemicals used 

in the highest quantity in the GOM are acids and brine solutions: Water-based 

Completion Fluids – 16,300,000 gal. (shallow water); 760,000 gal. (deepwater), specific 

chemical amounts were: 9,110,000 gal. of calcium chloride (shallow water); 426,000 

gal. (deepwater) and 4,660,000 gal. sodium chloride (shallow water); 218,000 gal. 

(deepwater); Hydrochloric Acid – 2,520,000 gal. solution containing 2,760,000 lbs. HCl 

(shallow water); 94,100 gal. solution containing 103,000 lbs. HCl (deepwater); 

Ammonium Chloride Overflush – 2,340,000 gal. of 5% solution containing 989,000 lbs. 

of ammonium chloride (shallow water); 87,400 gal. of solution containing 37,000 lbs. of 

ammonium chloride (deepwater). The production-treating chemicals used in the highest 

quantity in the GOM are: Hydration Inhibition Chemicals (Methanol) – 5,420,000 gal. 

(total); Corrosion Inhibitor – 2,500,000 gal. (total) and Hydration Inhibition Chemicals

(Glycols) – 1,460,000 gal. (total). As part of this study, the types and volumes of 

hazardous substances used, handled, and stored in offshore E&P operations were 

identified. Hazardous chemicals were defined as those substances listed in the U.S. 

Code of Federal Regulations (CFR) – Chapter 40, Protection of the Environment, Part 

116, that designates hazardous substances per the Clean Water Act. Only seven 

hazardous substances were found to be stored in amounts exceeding reportable 

quantities; sodium hydroxide, potassium hydroxide, zinc bromide, diethylamine, toluene, 

xylene, and naphthalene. Twenty-one chemicals were selected for detailed study 

based on volume estimates, screening-level toxicity data and professional judgement. 

For each of the selected chemicals a detailed chemical profile was developed to obtain 

a more definitive characterization of their use, storage, and potential for environmental 

impact. In addition, spill scenarios were developed and modeled for seventeen of the 

twenty-one profiled chemicals using Applied Science Associates’ (ASA) chemical spill 

model CHEMMAP. As part of the risk characterization, the results of the modeling effort 

were integrated with the toxicity data collected for the chemical profiles. The results of 
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this analysis indicate that a potential for impact exists for both zinc bromide and 

ammonium chloride. 

STUDY PRODUCTS: Arthur D. Little, Inc. 2001. Deepwater Program: Literature 

Review, Environmental Risks of Chemical Products Used in Gulf of Mexico Deepwater 

Oil & Gas Operations, Volume I: Technical Report and Volume II: Appendices. OCS 

Study MMS 2001-011 and MMS 2001-012. A final report to U.S. Department of the 

Interior, Mineral Management Service, Gulf of Mexico OCS Region, Metaire, LA 

Contract No. 01-98-CT-30900. Volume I: Technical Report 343 pp; Volume II: 

Appendices 382 pp. 

Arthur D. Little, Inc. 2001. Deepwater Program: Literature Review, Database of 

Chemical Products Used in Gulf of Mexico Deepwater Oil & Gas Operations. A 

Microsoft Access database submitted to U.S. Department of the Interior, Mineral 

Management Service, Gulf of Mexico OCS Region, Metaire, LA Contract No. 01-98-CT30900. 

*P.I.'s affiliation may be different than that listed for Project Manager(s).