Presented by Joe Ferris, PhD 6 June 2014 BMT Cordah Limited Aberdeen Scotland

Transcription

1 Environmental Considerations in Offshore Decommissioning and Removal Presented by Joe Ferris, PhD 6 June 2014 BMT Cordah Limited Aberdeen Scotland

2 Presentation Content Introduction Supporting Studies Selection of Preferred Option through a Comparative Assessment Impact Assessment Process Identifying Risk Principal Decommissioning Impacts Conclusions

3 BMT Cordah Decommissioning Services Environmental advisor support / secondment to decommissioning projects Tailored decommissioning programme(s) Comparative assessments or Best Practical Environmental Option (BPOE) assessment Environmental impact assessment Environmental risk identification workshops Marine and coastal habitat assessment Energy use and gaseous emissions Marine growth assessment Subsea acoustic modelling Waste management strategy and planning Management of cutting piles BMT Cordah supported CNRI with the decommissioning of their 188 m high Murchison Platform

4 Supporting Studies Scoping study Environmental Surveys pre and post decommissioning o Hydrocarbons o Heavy metals o Other Contaminants o Biota o Drill cuttings Pipeline survey Fisheries socio-economic study Energy use and emissions Marine growth assessment

5 Comparative Assessment of Options Risk to personnel Marine Impacts Risk to other users of the sea Energy/resource consumption Risk to those on land Safety Environment Other consequences Fisheries Amenities Societal Technical Feasibility & Cost Risk of major project failure Economics Communities

6 Impacts from Decommissioning Operations End-points Short-term Localised Obvious Long-term Possibly extensive Not immediately obvious Possible legacy issues May be cumulative

7 Environmental Impact Assessment Process Assessment of seabed condition Assessment of potential impacts to marine environment Assessment of atmospheric & terrestrial impacts Waste management Energy use associated with re-use and recycling Potential impacts to future users of the sea Determination of significance

8 Significance of Impacts As Determined Through Risk Assessment Methods

9 Principal Environmental Issues I. Waste Management II. Marine Growth III. Cuttings and Seabed Debris IV. Socioeconomic Concerns V. Hazardous Substances VI. Direct Impacts to Marine Ecosystem

10 I. Waste Management Waste management should align with the Waste Hierarchy Operator ensures obligations met Set targets for reuse / recycling of materials Initial segregation of waste is important Transboundary considerations Duty of Care Waste Hierarchy Eliminate Reduce Reuse Recycle / Recover Most Favourable Option Disposal Least Favourable Option

11 Waste Management Planning

12 II. Marine Growth Weight of marine growth on jackets & supports Occurrence of protected species Transfer of non-native species Onshore odour and disposal issues

13 Weights of Marine Growth Estimated wet weights (in air) in relation to jacket/support structural weight were: o Miller: 10% o Heather Alpha: 9% o NW Hutton: 6% Weights of marine growth received by the decommissioning contractors: Estimated Wet Weight (Tonnes) Actual Weight Received (Dry Weight in Tonnes) 1, (80% reduction) (82-95% reduction)

14 Management of Marine Growth Current marine growth management is company- and location- specific Opportunities exist for more effective technologies Landfill is a common disposal end point Composting and landspreading are alternatives to landfill Bulk removal of marine growth at sea Natural drying

15 III. Drill Cuttings and Seabed Debris Drill cuttings and muds o medium sized discharges (5,000 to 20,000 tonnes) o larger discharges (>20,000 tonnes) Contaminants in cuttings piles: o hydrocarbons o heavy metals o other chemicals from drilling mud additives Potential ecotoxicological affects Debris that may impact fishermen

16 Example of a Large Cuttings Pile volume of 22,545m 3 footprint area of 6,840m 2 elevated levels of total hydrocarbons and PAHs oil loss to water column predicted at 6 tonnes/year

17 IV. Socioeconomics Concerns Commercial and Recreational Fisheries Impacts to onshore resources Waste disposal and chemical contaminants Shipping and transit Obstructions left on the seabed Stakeholders, regulators & public

18 Impact of Pipelines and Subsea Structures

19 V. Hazardous Substances Radioactive Materials (NORM) Tank Contents (chemical soup) Hydrogen sulphide gas Topside materials, e.g. asbestos, PCBs, lead paint

20 VI. Direct Impacts to Marine Ecosystem Disturbance to Seabed Sensitive Species & Habitats Noise Impacts

21 Beneficial Outcomes from Decommissioning Increased access to fishing grounds Removal of obstructions to commercial shipping Removal of source of potential environmental contaminants Re-establishment of marine habitat Economic benefits to suppliers and service providers Use of jackets and platforms for habitat enhancement (often referred to as rigs-to-reefs)

22 Use of Platforms for Habitat Enhancement Proposed as replacement for or enhancement of declining natural reef ecosystems Potential benefits o enhance biological productivity o improve population connectivity o prevent trawl damage / protect deep water reefs Potential drawbacks / concerns o physical habitat damage o spread of invasive species o change marine food webs o release of contaminants over time

23 Methods for Creating Reefs from Platforms Tow and place platform at designated location / area o The rig is submerged and converted into artificial reef o Primary costs in towing and cutting o Divers cutting the jacket legs below the mud line o Can be expensive, labour intensive Topple in place o The remaining portion of the platform is completely submerged and converted into artificial reef o Primary cost is in cutting o Lower costs and time savings. Partial removal of platform o Remove a certain portion of the platform o Remaining part of the platform is completely submerged and left at the drilling site o Primary cost is also cutting o Reduces the removal costs and risks for divers

24 Using Rigs-to-Reefs as Disposal? Concern that placement of rigs for reefs used to legitimise the dumping of waste or other materials UNCLOS (1982) calls for the adoption of regional rules, standards and recommended practices and procedures to prevent, reduce and control pollution of the marine environment from dumping and from seabed activities subject to national jurisdiction Intent of National and International Guidance to: o prevent pollution or degradation of the marine environment; o ensure that placement of artificial reefs is not used as a mechanism to circumvent the provisions of the London Convention on the dumping of waste; o promote artificial reef development that has environmental benefits Current concepts: increase biomass; create conservation hotspots; reestablish biological community; ecotourism; or compensation for habitat loss Clear domestic laws and institutional organization are needed

25 A Few Conclusions Environmental risk and impacts should be identified early in decommissioning planning Both localized, short term and wider, long-term impacts need to be considered Beneficial outcomes should be highlighted and negative risks mitigated Reuse and recycling is a reasonable expectation Artificial reefs for ecological and fisheries enhancement or the protection of endangered species are legitimate under international law Goals of a rigs-to-reef program must be clearly defined

26 Thank You