Environmental Engineering Reference
In-Depth Information
Table 4 Estimated water requirements per well for drilling and fracturing in dif-
ferent shale gas plays (from Mantell
10
and Cuadrilla Resources).
11
Shale Play
Drilling (m
3
)
Fracking (m
3
)
Total (m
3
)
Barnett (US)
950
14000
14950
Haynesville (US)
2300
19000
22300
Fayetteville (US)
250
19000
19250
Marcellus (US)
400
21000
21400
Eagle Ford (US)
500
23000
23500
Bowland Shale (UK)
11
900
8400
9300
reflect the water used for a single exploratory borehole rather than multi-
stage hydraulically fractured production well.
It is therefore very dicult to estimate how much water will be required in
the UK, and in different locations, for shale gas operations because of the
significant uncertainty about how the industry may develop and how much it
will differ from that elsewhere in the world. The only practical way to con-
sider the potential implications is to examine a number of possible scen-
arios. This has been done as part of the Strategic Environmental Assessment
(SEA) for unconventional gas development in the UK, where a range of be-
tween 10 000 and 25 000 m
3
has been considered.
12
The SEA considered two
activity scenarios: high and low development, each with a number of as-
sumptions being made that resulted in estimates of the total number of
production wells ranging from 180 to 2880 and each requiring to be re-
fractured once during its lifetime. The resulting range for total water re-
quirement was between 3.6 and 144 million m
3
.
This water would not all be needed at the same time or in the same lo-
cation and so an additional major complication is the rate at which the wells
would be drilled and hydraulically fractured, and where they will be. Since
this information is unavailable as yet, any estimates of water demand for
shale gas in the UK are purely speculative. However, if we consider one de-
velopment scenario proceeding with 100 wells being drilled and completed
each year this would require 2.5 million m
3
, based on the maximum water
usage used in the SEA. This is a large number, but how does it compare to
how much we already use each year? The most recent UK Government
statistics on water abstraction (www.gov.uk) for 2012 estimated that the total
non-tidal freshwater (surface water and groundwater) abstraction for
England and Wales was 11 700 million m
3
. This would suggest an overall
demand for shale gas equivalent to approximately 0.02% of overall annual
abstraction. A breakdown of the most recent water use estimates for England
and Wales is shown in Table 5.
Overall shale gas requirements are relatively modest, but the challenge
comes from sourcing the water and transporting it to the site at the time
required. Whilst some areas of the UK have plenty of water others do not,
and there may already be significant stress on water resources in these areas
and little, if any, room for additional demand. This is particularly (although
