80
Measurement of air emissions from oil and gas production operations and other
processes have been made using a variety of methods, including direct measurements of specific chemicals, and downwind measurements using chemical tracers to
identify sources (e.g., Nathan et al. 2015; Allen 2016; Pekney et al. 2018). A focus
area on natural gas operations in particular has been the characterization of methane
emissions, since methane is the main component of natural gas (e.g., Omara et al.
2018; Johnson et al. 2019; Ren et al. 2019). Methane leakage from wellbores and
surface equipment like pipelines and compressors is a concern due to its flammability in air, and also because methane is a more powerful GHG than CO 2 , although it
is less persistent in the atmosphere. Other emission measurements have included
volatile organic compounds (VOCs) (Pétron et al. 2014), nitrogen oxides (NOx)
(Goetz et al. 2015), black carbon soot (Schwarz et al. 2015) and dust (Litovitz
et al. 2013).
The air pollution associated with fracking and other O&G operations falls into
three main categories: (1) particulate matter, (2) organic gases, and (3) nitrogen
oxides. Particulate matter or PM consists of dust and smoke from activities like site
preparation and drilling activities, material transport on and off the pad, and proppant handling and use. Sources of PM include diesel and other engine exhaust, tire,
brake and road dust, and silica dust from proppant sand (Moore et al. 2014). Organic
gases include VOCs like benzene, toluene, ethylbenzene and xylenes (known collectively as BTEX) from engine exhaust, well completions, vented tanks, fluid
transfer operations, flaring, equipment leaks, pneumatic controllers and valves
(Luck et al. 2019), and storage and transport of drilling waste (Allen 2016). Organic
gases may also consist of light hydrocarbons such as methane, ethane, propane, and
butane that volatize into the air when formation water is brought to the surface and
stored in open pits or vented tanks (Pekney et al. 2014). Nitrogen oxides or NOx are
a byproduct of high-temperature combustion and can be found in engine exhaust
during site preparation, material transport, drilling and fracking, and gas compressors (Zielinska et al. 2014).
5.1 Particulate Matter
Diesel and gasoline-powered construction equipment used for site preparation,
drilling, and hydraulic fracturing emit nitrogen oxides (NOx), particulate matter
(PM), volatile organic compounds (VOCs), polyaromatic hydrocarbons (PAHs),
methane (CH4), and other compounds into the air (Moore et al. 2014). A significant
air quality concern with the oil and gas production process in general, and fracking
in particular, is the amount of PM emitted by these operations.
Referring back to the hydraulic fracturing operation pictured in Fig. 2.1, a puff
of diesel smoke is visible above the pump trucks, and a haze of dust is present over
the sand tank at the left rear of the photo. Both of the clouds in this photo are composed of particulate matter, defined by the EPA as a mixture of solid particles
and liquid droplets found in the air (https://www.epa.gov/pm-pollution/
5 Fracking and Air Quality
Measurement of air emissions from oil and gas production operations and other
processes have been made using a variety of methods, including direct measurements of specific chemicals, and downwind measurements using chemical tracers to
identify sources (e.g., Nathan et al. 2015; Allen 2016; Pekney et al. 2018). A focus
area on natural gas operations in particular has been the characterization of methane
emissions, since methane is the main component of natural gas (e.g., Omara et al.
2018; Johnson et al. 2019; Ren et al. 2019). Methane leakage from wellbores and
surface equipment like pipelines and compressors is a concern due to its flammability in air, and also because methane is a more powerful GHG than CO 2 , although it
is less persistent in the atmosphere. Other emission measurements have included
volatile organic compounds (VOCs) (Pétron et al. 2014), nitrogen oxides (NOx)
(Goetz et al. 2015), black carbon soot (Schwarz et al. 2015) and dust (Litovitz
et al. 2013).
The air pollution associated with fracking and other O&G operations falls into
three main categories: (1) particulate matter, (2) organic gases, and (3) nitrogen
oxides. Particulate matter or PM consists of dust and smoke from activities like site
preparation and drilling activities, material transport on and off the pad, and proppant handling and use. Sources of PM include diesel and other engine exhaust, tire,
brake and road dust, and silica dust from proppant sand (Moore et al. 2014). Organic
gases include VOCs like benzene, toluene, ethylbenzene and xylenes (known collectively as BTEX) from engine exhaust, well completions, vented tanks, fluid
transfer operations, flaring, equipment leaks, pneumatic controllers and valves
(Luck et al. 2019), and storage and transport of drilling waste (Allen 2016). Organic
gases may also consist of light hydrocarbons such as methane, ethane, propane, and
butane that volatize into the air when formation water is brought to the surface and
stored in open pits or vented tanks (Pekney et al. 2014). Nitrogen oxides or NOx are
a byproduct of high-temperature combustion and can be found in engine exhaust
during site preparation, material transport, drilling and fracking, and gas compressors (Zielinska et al. 2014).
5.1 Particulate Matter
Diesel and gasoline-powered construction equipment used for site preparation,
drilling, and hydraulic fracturing emit nitrogen oxides (NOx), particulate matter
(PM), volatile organic compounds (VOCs), polyaromatic hydrocarbons (PAHs),
methane (CH4), and other compounds into the air (Moore et al. 2014). A significant
air quality concern with the oil and gas production process in general, and fracking
in particular, is the amount of PM emitted by these operations.
Referring back to the hydraulic fracturing operation pictured in Fig. 2.1, a puff
of diesel smoke is visible above the pump trucks, and a haze of dust is present over
the sand tank at the left rear of the photo. Both of the clouds in this photo are composed of particulate matter, defined by the EPA as a mixture of solid particles
and liquid droplets found in the air (https://www.epa.gov/pm-pollution/
5 Fracking and Air Quality