Environmental Engineering Reference
In-Depth Information
Table 3 Truck visits over lifetime of six well pads.
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Per well
Per pad
Purpose
Low
High
Low
High
Drill pad and road construction equipment
10
45
Drilling rig
30
30
Drilling fluid and materials
25
50
150
300
Drilling equipment (casing, drill pipe, etc.)
25
50
150
300
Completion rig
15
15
Completion fluid and materials
10
20
60
120
Completion equipment (pipe, wellhead)
5
5
30
30
Hydraulic fracture equipment (pump trucks, tanks)
150
200
Hydraulic fracture water
400
600
2400
3600
Hydraulic fracture sand
20
25
120
150
Flow back water removal
200
300
1200
1800
Total
4315
6590
... of which, associated with fracturing process:
3870 5750
90% 87%
The emissions from the hydraulic fracturing process, which uses more
fuel than a conventional well, relate to emissions from the fuel used by the
high-pressure pumps required. New York State reports that emissions from
these pumps, based on an average fuel use, for hydraulic fracturing of eight
horizontally drilled wells in the Marcellus Shale used a total of 110 000 litres
of diesel fuel, producing 295 tonnes of carbon dioxide per well.
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As with all industrial sites, during the construction and hydraulic frac-
turing phases there will be heavy road trac moving in and out of the site.
New York State (2009)
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provides estimates of truck visits to a typical site.
These are summarised in Table 3, giving trips per well and per well pad
(based on six wells per pad). This suggests a total number of truck visits of
between 4300 and 6600 of which about 90% are associated with the
hydraulic fracturing operation.
These truck visits will also have an adverse impact on greenhouse gas
emissions.
During the production phase the amount of trac will be minimal, but
once the site is completed there will again be considerable heavy trac
movements as equipment is removed and the site returned to its original use.
Thefossilfuelemissionsofshalegasversus conventional gas per well are
given in Table 4 which, in addition to the emissions associated with the hori-
zontal drilling and the hydraulic fracturing, also takes into account the trans-
port of water to and from the site and the wastewater treatment. Water UK
estimated the emissions to the atmosphere at the wastewater treatment plant to
be 0.406 tonnes of carbon dioxide per thousand cubic metres of water treated.
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2.2.2.7 Road Trac
In the UK many of the shale gas sites will be in rural locations served by
minor roads which are often narrow and of relatively light road construction
