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types of offshore drilling waste

The various drilling operations; exploration and or plug and abandonment operations result in different types of slops. Most of this waste cannot be processed on the platform itself because its components are too complex to be treated with standardised preprogrammed equipment. Especially when waste streams are mixed together or stored for longer periods of time. This waste (slop) is therefore normally transported to an onshore treatment plant.

There are different ways of treating slops. Nature Group has defined four categories, each of which represents a specific treatment:

Category
Category I
Oil-contaminated water
Source:
Deck drains and rainwater
Volume:
High volume >4000 m³ per annum
Characteristics:
Mainly water, brine, less than 5% oil and solids
Average waste reduction:
95%
Solution:
Category
Category II
Water lightly polluted by OBM
Source:
Category I + displacements, pit washings
Volume:
2000-3000 m³ per annum
Characteristics:
Sludge + water, less than 20% oil and solids
Average waste reduction:
80 - 90%
Solution:
CTU + STU
Category
Category III
Water heavily polluted by OBM
Source:
Category I and II + push pills, soap pills, other chemicals, often resulting from plug& abandonment operations
Volume:
1000-4000 m³ per annum
Characteristics:
Mainly sludge, more than 20% oil and solids or highly polluted with chemicals
Average waste reduction:
60 - 85%
Solution:
CTU + STU
Category
Category IV
Produced water
Source:
Water from oil or gas production
Volume:
High Volume >10,000 m³ per annum
Characteristics:
Mainly water and oil, few or no solids
Average waste reduction:
>90%
Solution:
CTU