3. The new “fracking” technique to recover unconventional shale gas will require
a significantly large use of water. In recent years, the recoveries of shale and
tight gases have revolutionized the gas industry. Shale deposits were formed
about 350 million years ago. Shale is a very fine-grained sedimentary rock,
which is easily breakable into thin parallel layers. It is a very soft rock, but
it is impermeable to water in its natural state. The shales can contain natural
gas usually when two thick black shale deposits “sandwich” a thinner area of
shale. Due to the nonporous and impermeable properties of these shales, the
extraction of natural gas from shale formation is more difficult.
Similarly, the “tight gas” is a gas that is stuck in a very tight and unusually i mpermeable h ard r ock o r i n a s andstone o r l imestone f ormation t hat i s
unusually impermeable and nonporous (tight sand). Unlike extracting conventional natural gas, a significant more effort has to be put into extracting
gas from a tight formation. Recently, both shale and tight gases have been
successfully recovered using a new technique of fracking, by which impermeable rocks in both cases are fractured using a horizontal or directional
drilling technique, which uses high-pressure water solutions (with many
chemical additives) to fracture impermeable and tight shale or sand matrix.
The dramatic expansion of shale gas industry will require water (with chemicals) as “fracking fluid” to fracture impermeable shale rocks. Additional
water will also be required to capture tight gas by the “fracking process”
[18–37]. A significant increase in water requirement for this process may
cause local conflicts due to competing needs for water. We will briefly discuss the role of water in this successful but somewhat controversial process.
4. Additional water will be required for the recovery of solid fuels such as
coal, oil shale, tar sand, and uranium as these sources become harder to
recover due to their locations and recovery methods. Both surface mining
and deep mining are used in the recovery process. The extraction processes
can be carried out outside the mine or in situ. A significant amount of water
is used for these processes and water is essential for recovery and treatment
of these fuels [38–42]. The use of water in the recovery of tar sands will
grow very rapidly as more and more tar sands are discovered deeper into
the ground and at a lower concentration in the sand.
Role of Water in Recovery and Production of Raw Fuels
19
2.2 inCreased Water UsaGe FOr reCOVery OF COal Bed
methane and Gas FrOm GeOPressUriZed ZOnes
Recovery of methane from coal beds is an attractive prospect for development
because of the ability of coal bed to retain a large amount of methane gas; coal is
able to store six to seven times more gas than an equivalent volume of rock common
to conventional gas reservoirs. In most regions of the United States, coal bed methane wells produce between 100 and 500 thousand cubic feet of methane per day. The
amount of methane in a coal deposit depends on the quality and depth of deposit.
In general, the higher the energy value of the coal and the deeper the coal bed, the
more methane in the deposit [3–12]. Like the United States, the extraction of coal
bed methane is gaining a significant momentum in Canada as well [8]. In principle,
a significantly large use of water. In recent years, the recoveries of shale and
tight gases have revolutionized the gas industry. Shale deposits were formed
about 350 million years ago. Shale is a very fine-grained sedimentary rock,
which is easily breakable into thin parallel layers. It is a very soft rock, but
it is impermeable to water in its natural state. The shales can contain natural
gas usually when two thick black shale deposits “sandwich” a thinner area of
shale. Due to the nonporous and impermeable properties of these shales, the
extraction of natural gas from shale formation is more difficult.
Similarly, the “tight gas” is a gas that is stuck in a very tight and unusually i mpermeable h ard r ock o r i n a s andstone o r l imestone f ormation t hat i s
unusually impermeable and nonporous (tight sand). Unlike extracting conventional natural gas, a significant more effort has to be put into extracting
gas from a tight formation. Recently, both shale and tight gases have been
successfully recovered using a new technique of fracking, by which impermeable rocks in both cases are fractured using a horizontal or directional
drilling technique, which uses high-pressure water solutions (with many
chemical additives) to fracture impermeable and tight shale or sand matrix.
The dramatic expansion of shale gas industry will require water (with chemicals) as “fracking fluid” to fracture impermeable shale rocks. Additional
water will also be required to capture tight gas by the “fracking process”
[18–37]. A significant increase in water requirement for this process may
cause local conflicts due to competing needs for water. We will briefly discuss the role of water in this successful but somewhat controversial process.
4. Additional water will be required for the recovery of solid fuels such as
coal, oil shale, tar sand, and uranium as these sources become harder to
recover due to their locations and recovery methods. Both surface mining
and deep mining are used in the recovery process. The extraction processes
can be carried out outside the mine or in situ. A significant amount of water
is used for these processes and water is essential for recovery and treatment
of these fuels [38–42]. The use of water in the recovery of tar sands will
grow very rapidly as more and more tar sands are discovered deeper into
the ground and at a lower concentration in the sand.
Role of Water in Recovery and Production of Raw Fuels
19
2.2 inCreased Water UsaGe FOr reCOVery OF COal Bed
methane and Gas FrOm GeOPressUriZed ZOnes
Recovery of methane from coal beds is an attractive prospect for development
because of the ability of coal bed to retain a large amount of methane gas; coal is
able to store six to seven times more gas than an equivalent volume of rock common
to conventional gas reservoirs. In most regions of the United States, coal bed methane wells produce between 100 and 500 thousand cubic feet of methane per day. The
amount of methane in a coal deposit depends on the quality and depth of deposit.
In general, the higher the energy value of the coal and the deeper the coal bed, the
more methane in the deposit [3–12]. Like the United States, the extraction of coal
bed methane is gaining a significant momentum in Canada as well [8]. In principle,