Publication
| Title: | "Disposal of oil-based cuttings" |
| ISBN no.: | 82-7220-894-6 |
Category: |
Reports (Rapporter) |
| Authors: | Simon J. Cripps
Person Ekstern
Person Ekstern
Odd Ketil Andersen
Person Ekstern
Person Ekstern
Craig D. Marken
John Eirik Paulsen
Person Ekstern
Person Ekstern
Troels G. Jacobsen
Inge Brun-Henriksen |
| Research group: | Marint miljø (Marine environment ) |
| Distribution restriction: | Open |
| Order no.: | 1998/097 |
| Price.: | 160 |
Abstract:
Nineteen operations comprising the seven options for handling existing oily
drill cuttings piles were described: leave the piles undisturbed;
bioremediation in situ; capping; gravel dumping; spreading; retrieve with
suction; retrieve with dredging; retrieve with a sea-floor crawler; sub-sea
entombment in a pit; reinjection into a well; bioreactor treatment offshore;
super-critical treatment offshore; land-farming; mechanical treatment onshore;
distillation onshore; stabilisation onshore; combustion onshore; landfill,
either of treated or untreated wastes. Where possible, each operation was
described in terms of eighteen parameters including equipment, handling rates,
costs, emissions and discharges, risks and environmental impacts.
The data presented in Chapters 2 to 10 of the study, and summarised in Section
11, were then used to assess the performance of the key operations or
end-points, in terms of the criteria of environmental impact, energy use,
safety, cost and technical feasibility. The “performance” of the key
operations and end-points was examined on the basis of these criteria, both
when taken individually and when taken in various combinations. It was thus
possible, in an intra-generic group comparison, to identify one specific
decommissioning option which was judged to be particular suitable for
incorporation into a generic option. The relative performances of these
selected options were then assessed in an inter-generic group comparison, using
the same criteria of environmental impact, energy use, safety, cost and
feasibility, both individually and in combination.
Of the specific cutting pile handling techniques evaluated, covering with
gravel using a fall-pipe delivery system appeared overall to offer several
advantages compared with other covering or capping techniques, a sea-floor
crawler was an appropriate retrieval technique, a bioreactor an appropriate
offshore treatment technique, and distillation was judged a suitable onshore
treatment technique. Using these specific techniques in the evaluation of the
different total handling processes, retrieval, slurrification and reinjection
appeared a particularly promising commercially available technique.
Bioremediation in situ appeared to offer much potential, but the method is
currently not developed. Leaving in place was also promising, but aspects such
as decommissioning damage, hindrance and liability need to be considered. The
reinjection option has a moderate level of environmental impact as a result of
the requirement to retrieve the cuttings from the sea-floor and has a net
energy consumption which appears to be in the middle of the range that was able
to be determined for the nine generic options. In all other respects this
option performs well or very well: it is safe, commercially available and
affordable. It does though require that necessary topsides reinjection and
buffer storage facilities are available, and most importantly, the rock
formation is able to accept sufficient quantities of the reinjected slurry.
All the handling options had advantages and disadvantages relative to the other
options, so a case-by-case assessment of each pile is needed. For this reason,
this study has avoided the ranking of operations, or the recommendation of any
one specific operation, end-point or generic option. The methods and data
presented in this study can be used to assist such assessment studies, as well
as to tentatively indicate an overall policy.
Keywords:
Oily drill cuttings, bioremediation, reinjection, respreading, treatment, disposal, environmental impacts, costs, emissions, energy.
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