26
Water for Energy and Fuel Production
The drilling and hydraulic fracturing of horizontal gas wells on average
requires 3.5 million gallons of water. This water generally comes from surface
water bodies or from groundwater, private water sources, municipal water, and
reused produced water. Water, however, plays a very significant role in recovering
unconventional gas such as deep gas, tight gas, gas from geopressurized zones,
shale gas, and coal bed methane. Section 2.2 showed the increased usage of water
for recovery of coal bed methane and the gas from geopressurized zones. In this
section, we briefly discuss the additional usage of water required to recover shale
gas and tight gas using the fracking process. This hydraulic fracturing process to
release trapped gas in tight and nonporous geological matrix requires a substantial amount of water and chemical additives.
The recovery of shale gas and tight gas uses horizontal drilling and hydraulic
fracturing (i.e., fracking). Over the next 25 years, the unconventional gas production will increase from 15% of the total current production to about 77% of the total
gas production. Unconventional natural gas reserves are located at varying depths
below the ground. In Texas’ Barnett and Haynesville/Bossier plays, for example, the
natural gas-producing areas are 1,000–12,000 ft below the ground. In Michigan and
Illinois, natural gas-producing areas are much shallower ranging from hundreds of
feet to 2000 ft below the ground. All of these reservoirs now use horizontal drilling
and fracking process [17,29,35,36].
The drilling and hydraulic fracturing of a horizontal shale gas well uses large volumes of water. The EPA reports [30,31,34] that fracturing shale gas wells requires
between 2.3 and 3.8 million gallons of water per well. An additional 40,000 to
1 million gallons of water is required to drill the well. This is considerably more
water than is required for conventional gas because the wells to access shale gas
and tight gas are deeper. The data [26,33,35] show that for shale gas in Marcellus
region, 4.5 million gallons of water per well is required. Water requirements within
Texas Eagle Ford shale area can be even greater where the fracking process can
use up to 13 million gallons of water per well with additional water requirement for
drilling the wells [17,18,22,36]. Within the state of Texas, the water requirement
does depend on shale plays; for example, water requirement in Barnett shale play
can range from 1 to 8 million gallons of water per well; in Haynesville and Bossier
shale play, it can range from 1 to 10 million gallons per well; and in Woodford,
Pearsall, and Barnett-PB shale plays, it can be as low as 1–5 million gallons per
well [17–19,22,36].
The water used in the fracking process also contains some harmful chemicals such
as acids, scale inhibitors, iron control agents, surfactants, friction reducing agents,
corrosion inhibitors, gelling agents, and bactericide/biocide compounds. Once the
fracking process is complete, the fracking fluid is withdrawn from the well, but this
withdrawal rate can be as low as 20% of the injection rate. The remaining fluid can
have a harmful effect on the underground water aquifers [20–22,24,30–32] due to its
chemical contents. The water withdrawn from the well is accumulated in the surface
pond and treated before it is reused or reinjected in the well. The fracking process
not only requires a large amount of water but also creates a number of water-related
issues such as (1) water withdrawals, (2) groundwater contamination associated with
well drilling and production, (3) waste water management, (4) surface spills and