ENVIRONMENTAL STATEMENT BARDOLINO DEVELOPMENT

Bardolino Development Environmental Statement
3.4.7 Cementing Chemicals
Cement is used to secure the steel casing in the well bore, and the cementing chemicals are
used to modify the technical properties of the cement slurry. During cementing operations,
the majority of these chemicals are left downhole but a small quantity of cement may be
discharged onto the seabed around the top of the casing. However, the chemicals used will
be contained within inert cement and will therefore not pose a threat to the marine
environment. Careful estimates of the final volume of the hole will be made during drilling,
and the volume of cement used will be adjusted accordingly to minimise the risk of excess
cement being squeezed out of the hole onto the seabed.
A number of chemicals will need to be added to the cement. The exact chemical constituents
required to formulate the cement will be confirmed during the final stages of well design.
They will be included in the detailed chemical risk assessment of the PON 15B which will be
submitted to BERR at least 28 days prior to commencement of drilling activities as required
by the Offshore Chemical Regulations 2002.
3.4.8 Contingency Chemicals
Contingency chemicals will be held on the rig for use in unplanned events. Potential
applications would be to free a stuck drill string, or seal highly porous or fractured zones to
prevent the uncontrolled loss of drilling fluid. A detailed risk assessment for contingency
chemical use will be submitted to BERR as required by the Offshore Chemical Regulations
2002.
3.4.9 Handling Mud and Cuttings
Once on board the rig, drill cuttings are removed from the drilling mud by solids control
equipment. Where LTOBM is used the mud and cuttings will be treated by the solids control
equipment before being intercepted by a collection device. The cuttings will be transferred
from the solids control equipment and then either dried and collected in skips ready for
transfer to a supply vessel, or slurrified and pumped directly to the bulk tanks of a supply
vessel for transport to shore. Once onshore the cuttings are processed until they have very
low oil content and then disposed of. The base oil residue recovered during this process is
returned to the mud company.
Shell’s “Ship to Shore Cuttings Disposal Guidelines” will be followed during the planned
LTOBM phase. In the event of unexpected hole conditions (e.g. faster than expected
penetration rates), equipment breakdown or failure, or operational and logistics downtime due
to adverse weather conditions, contingency arrangements will be in place to permit storage of
cuttings on board the rig until normal operations are resumed. If necessary, unless personnel
safety or installation integrity is threatened, drilling will cease in preference to the discharge of
LTOBM-coated cuttings to sea. However, in the event of a major safety incident where no
compromise on safety risks to personnel or asset can be made, the contingency will exist to
divert limited quantities of cuttings overboard.
3.4.10 Well Clean-up and Testing Operations
Once drilling has been completed, the Bardolino well will be circulated clean prior to
completion, and then tested. The exact chemicals required for these processes will be
included in the chemical risk assessment of the PON 15B as required by the Offshore
Chemical Regulations 2002. Hydrocarbons produced during the well flow clean-up and
testing will be flared.
The aim of well clean-up is to remove detritus from the well prior to running the completion. It
also removes solids that could impair both mechanical operations in the well bore and
reservoir performance once the well has been perforated.
The potential emissions from well clean-up and testing of the development well have been
calculated based on a total testing and clean-up period of 48 hours with a maximum of 15,000
bbls of oil, with an expected GOR of 870 scf/bbl (
Table 3.4). This represents a worst case for emissions. There is no intention to perform an
extended well test, and it is likely that the quantity of oil flared during well clean-up and testing
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