Drill Cuttings Issues in Decommissioning

Derek Moore, Formerly Marine Scotland

Drill Cuttings Issues in Decommissioning

September 2014

Derek Moore

3

• Brief History

• Environmental impacts

• Decommissioning

• Post Decommissioning

Drilling muds

4

DRILLING MUDS

• Cool and lubricate drill

bit

• Transport cuttings out

of well

• Stabilise well walls

• Provide hydrostatic

head

Pile Morphology

5

Clyde Brent South

Brent Alpha

Beryl Alpha Miller

Water based vs Oil based?

6

“…we only use water based

muds in the North Sea…

… however we do routinely add

10-15% diesel to improve its

performance !”

Replacement mud types

7

Alternatives to diesel based

muds

POBM Pseudo Oil

Based Mud

SOBM Synthetic Oil

Based Mud

LTOBM Low Toxicity

Based Mud

OSPAR 2000/3

8

9

Oil Based Mud

Water Based Drilling Fluid

Additives

Brines e.g. Calcium Chloride

Dihydrate

Sodium Hydroxide

Sodium Carbonate

Potassium Chloride

Potassium Aluminium

Silicate

Silica

Disodium Duhydrogen

Diphosphate

Sucrose

Sodium Bicarbonate

Citric Acid Monohydrate

Weighting Chemical Barite

Calcium Carbonate

Silica

Acidity Control Chemical Calcium Hydroxide

Viscosifier

Quaternary Ammonium

Compounds

Glyoxal

Xanthan Gum

Lost Circulation Material Nut Shells

Synthetic Fibres

Synthetic Flakes

Walnut Shells

Wood Fibres

Graphite

Carbon

Calcinated Petroleum Coke

Cellulose

Kaolin

Polyalkalene Glycol

Polyvinyl Alcohol

Sodium Sulphate

Wollastonite

Fluid Loss Control Chemical Cellulose Fibre

Gilsonite

Methylstyrene/Acrylate

Copolymer

Synthetic Amorphous Silica

Mica

Nut Shells

Wood Fibres

Emulsifier

Dipropylene Glycol Monomethyl

Ether

Petroleum Distillate

Fatty Acids

Modified Amidoamine from FA

OPF Base Oil Hydrocarbons

Petroleum Distillate

OPF Additive

Dipropylene Glycol Monomethyl

Ether

Petroleum Distillate

Modified Amidoamine from FA

Shale Inhibitor/Encapsulator Lignite

Sodium Asphalt Sulphonate

Pipe Release Chemical Citric Acid Monohydrate

Disodium Dihydrogen

Diphosphate

Potassium Chloride

Ethylene Glycol Monobutyl

Ether

Biocide Triethanol

EDTA (ethylene-dinitrilo)

tetraacetic acid

Hydrogen Sulphide Scavenger Iron (III) Oxide

Silicon Dioxide Crystalised

Triethanol

Detergent / Cleaning Fluid D-glucopyranose

Tetrapotassium Pyrophosphate

Benthic impacts

10

OSPAR Recommendation 2006/5

11

Post Decommissioning

12

Plan and relief of the Murchison drill

cuttings pile

Fishing operations

13

14

Post Decommissioning

Fishing Gear Disturbance

15

Fishing Gear Disturbance

16

Conclusions

17

• Acceptable case can be made

for leaving piles to degrade

naturally

• Little impact from fishing

operations

• Must recognise that fishing

gear has the potential to

become contaminated and

influence the marketing chain

• Use of technological advances

such as FishSAFE and web

based information systems

such as the Kingfisher

Fortnightly Bulletin.