Page 69 - Environmental Control in Petroleum Engineering

Drilling and Production Operations 5?

normally is not concentrated in sufficient quantities to cause environ-
mental impact, although it can be temporarily concentrated in low-
lying areas.
Lead-210 is of particular concern to the natural gas liquids industry
(Gray, 1993). When lead-210 is formed, it precipitates on equipment
surfaces, forming an extremely thin layer of radioactive film.
Although significant levels of NORM have been seen at some
production operations, it is not normally encountered at drill sites. The
drilling process does not provide a way for significant concentrations
of NORM to accumulate.

2.3 AIR EMISSIONS

A wide variety of air pollutants are generated and emitted during
the processes of finding and producing petroleum. These air pollutants
include primarily oxides of nitrogen (NO x), volatile organic compounds
(VOCs), oxides of sulfur (SO x), and partially burned hydrocarbons
(like carbon monoxide and particulates). Dust from construction and
unpaved access roads can also be generated.
Volatile hydrocarbons, including aromatics, are emitted during the
regeneration of glycol from natural gas dehydration (Grizzle, 1993;
Thompson et al., 1993). Halon gases are used at many drilling and
production sites for fire suppression. These gases have been identified
as an ozone-depleting chlorofluorocarbon (CFC), and their use releases
them to the atmosphere.

2.3.1 Combustion

The largest source of air pollution in the petroleum industry is the
operation of the internal combustion engines used to power drilling
and production activities, such as drilling rigs, compressors, and
pumps. These engines can be powered by either natural gas or diesel
fuel. The two primary pollutants emitted from these engines are oxides
of nitrogen, primarily NO and NO 2, and partially burned hydrocarbons.
The nitrogen oxides are commonly referred to as NO x. During combustion,
about 3.5 pounds of NO x can be generated for each barrel of fuel burned.
Emissions of NO x from petroleum industry operations in 1975
totaled 1.3 million U.S. tons. This level was about 11% of the total
NO emissions from all stationary sources in the United States and