Environmental Statement - Maersk Oil

Balloch Field Development Environmental Statement
Section 5 Assessment of Potential Impacts and Controls
Table 5‐3 Summary of emissions associated with the drilling support vessels assuming three production wells.
Vessel type
Fuel use
(te)
Emissions (te)
CO 2 NO x N 2O SO 2 CO CH 4 VOC
3 Anchor Handling Vessels 3,690 11,808 219 0.81 14.76 57.93 0.66 7.38
Supply vessel 2,550 8,160 151.5 0.56 10.2 40.04 0.46 5.1
Standby vessel 166 532 9.9 0.04 0.66 2.61 0.03 0.33
Helicopter 360 1,152 21.4 0.08 1.44 5.65 0.06 0.72
Total from vessels 6,600 21,120 392 1.45 26.40 103.62 1.19 13.20
Emissions to air from well clean‐up and well testing
Well clean‐up is necessary to ensure the well no longer contains any drilling and completion related
debris (mud, brine, cuttings) which could potentially damage the topsides when completion and
production begin. A well test flow period may be required to obtain reservoir properties, flow rate
information and fluid samples dependent on the information obtained during the drilling of the
reservoir section. Emissions of CO2, CH4 and VOCs are higher during clean‐up and well test operations
than during rig and vessel activities associated with drilling and completions.
At the time of writing (August 2012), the volumes of hydrocarbons to be flared during well clean‐up
and testing were not known. A worst case of 2,000 te of oil per well was therefore assumed.
Atmospheric emissions resulting from the well test and clean‐up for the three proposed Balloch
production wells have been calculated using the EEMS emissions factors (EEMS, 2008) and are
presented in Table 5‐4. Total CO2 associated with flaring at the three wells equates to 0.49 % of that
produced by similar activities in 2009 in UKCS waters.
Table 5‐4 Summary of atmospheric emissions from the Balloch well clean‐up and well testing activities.
Hydrocarbons
flared (te)
Emissions (te)
CO 2 NO x N 2O SO 2 CO CH 4 VOC
Oil 6,000 19,200 22.2 0.49 0.08 108 150 150
2009 total hydrocarbon
well testing emissions
from UKCS offshore
activities 1
Anticipated well clean‐up
& testing emissions as a %
of the equivalent 2009
UKCS emissions
1 Source: EEMS 2009 data.
3,931,850 3,022 113 219 10,300 15,706 11,394
0.49 0.73 0.43 0.04 1.05 0.96 1.32
Emissions from the well clean‐up and well test will be released approximately 225 km from the
nearest coastline (UK). The prevailing winds from the south and southwest will carry the emissions
away from the nearest coastline with very high dispersion and dilution of emissions occurring in the
offshore environment (DTI, 2001).
All relevant permits and consents (PON15B, OPPC and PPC) will be applied for to cover the clean‐up
and well testing operations.
Proposed control measures for impacts associated with emissions to air during the drilling phase
Control measures to mitigate impacts from atmospheric emissions associated with drilling operations
are presented below.
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