Environmental statement - Flyndre and Cawdor - Maersk Oil

5‐ 4
Hydrocarbons
flared (te)
Flyndre and Cawdor Environmental Statement
Section 5 Assessment of Potential Impacts and Control Measures
Emissions (te)
CO 2 NO x N 2O SO 2 CO CH 4 VOC
Liquids 3,384* 10,829 12.51 0.273 0.044 30.9 84.6 84.6
Gas 1,805* 5,054 2.16 0.146 0.023 12.1 81.22 9.02
Total 15,883 14.67 0.419 0.067 73 165.82 93.62
2009 total hydrocarbon
well testing emissions
from UKCS offshore
activities,
3,931,850 3,022 113 219 10,300 15,706 11,394
Emissions from this
development as a % of
UKCS well testing
emissions
*Includes the three Cawdor wells
0.4 0.48 0.37 0.03 0.71 1.06 0.82
Note; Atmospheric emissions have been calculated using emissions factors from EEMS Atmospheric
Calculations Issue 1.810a (Austin, 2008).
Table 5‐4 Summary of emissions from the well clean up and well testing.
The emissions from the well clean up and well test will be released approximately 290 km from
nearest coastline (UK). The prevailing winds which are from the south and south west will carry the
emissions away from the nearest coastline with very high dispersion and dilution of emissions
occurring in the offshore environment (DTI, 2001).
5.1.2. DISCHARGES TO SEA
FLARE DROP OUT
During any flaring and clean up operations there is the potential for flare drop‐out (unburned
hydrocarbons) falling from the flare onto the sea surface, potentially causing an oily slick to form on
the sea surface. This could impact on the environment, particularly seabirds that may be using the
area during the well clean‐up operations. However seabird data obtained from the area suggests the
density of seabirds is generally relatively low throughout the year thus minimising the potential
impact of flare drop‐out.
In order to minimise the risk of flare drop‐out occurring a green burner will be used on the drill rig
which is designed to burn at a greater efficiency and consequently reduce the risk of flare drop‐out.
Proposed Control Measures
Period of well testing will be kept to a minimum
‘Green burners’ will be employed for well test operations, which will significantly reduce the
levels of unburned hydrocarbons entering the environment.
During flaring continuous observation of the sea surface will occur. The test will be
suspended should a significant sheen be observed
DISCHARGE OF DRILLING FLUIDS AND ASSOCIATED CUTTINGS
The top hole sections (36” and 17 1 /2”) of the Cawdor wells will be drilled using seawater and high
viscosity sweeps. The top hole sections of each well will produce 516 tonnes of cuttings which will be
discharged to the seabed.