A new study commissioned by the US Minerals Management Service (MMS) found that only two chemicals, zinc bromide and ammonium chloride, used by the oil and gas industry could be potential hazards in the Gulf of Mexico.
The study (MMS Study 2001-011 and 012) identifies chemicals used in the gulf and lists their properties, toxicity, usage patterns, and storage and handling practices. It uses spill modeling to evaluate the potential environmental risk for a select group of chemicals. In addition, the study covers an overview of relevant legislation.
MMS says it is using results from this study to modify reporting requirements for Gulf of Mexico operators.
Deepwater focus
MMS explains that from 1947 to 1985, exploration and development activities focused on the shallow waters of the continental shelf, but since the mid-1980s, deepwater exploration and development has accelerated rapidly.
MMS estimates that by year-end 1999, about 1,200 wells had been drilled in water depths exceeding 1,000 ft and production from these deepwater wells now surpasses shallow water production, despite the fact that only 4% of all Gulf of Mexico producing fields are in deepwater.
Chemicals have been used in gulf oil and natural gas exploration and production since the beginning of offshore resources development over a half-century ago. These chemicals are needed for the safe, cost-effective extraction of oil and gas resources.
The study classifies the chemicals used in offshore operations into four major classes: drilling fluids; cementing chemicals; completion, stimulation, and workover chemicals; and production-treating chemicals.
It found that definite differences are apparent in chemical use in deep and shallow gulf waters. Differences noted included:
- More drilling fluid chemicals needed in deepwater wells, possibly because of the nature of the formations and reservoirs encountered in these plays.
- More treating chemicals, such as hydrate inhibitors, needed for deepwater production.
- More treating chemicals, such as defoamers, needed because of the characteristics of the fluids produced from deepwater fields.
Hazardous chemicals
The study identified the types and volumes of hazardous substances used, handled, and stored in offshore exploration and production operations.
It defined hazardous chemicals as those substances listed in the US Code of Federal Regulations (CFR) - Chapter 40, Protection of the Environment, Part 116. This regulation designates hazardous substances per the Clean Water Act.
The study found only eight hazardous substances that might be stored in amounts exceeding reportable quantities. These eight are sodium hydroxide, potassium hydroxide, zinc bromide, hydrofluoric acid, diethylamine, toluene, xylene, and naphthalene.
For risk characterization modeling, the study integrated toxicity data collected for chemical profiles. It concluded that a potential for a hazardous impact exists for only two chemicals: zinc bromide and ammonium chloride.
It predicted the impact of zinc bromide based on a 45,000-gal release to the environment, but did not model ammonium chloride because of its similar behavior to potassium chloride.
With the potassium chloride as a surrogate for ammonium chloride, the study indicates a positive potential for environmental impact. But the study also qualified the results by saying that this was an indicator of potential risk that needed additional study.
