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Major accident and spill prevention

Preventing a major incident or spill is of paramount importance to all our operations. This is why strict planning, design and operating procedures are backed up with a comprehensive emergency response capability.

Preventing major accidents

The emphasis for major accident control remains prevention. We place substantial effort on both internally and externally assured well design, equipment inspection and operational audits for all drilling programmes as part of our commitment to prevent major incidents (see Asset protection and major accident prevention).

Emergency response planning

We prepare for the very low possibility of a high-impact event, and have robust plans in place to manage potential incidents. In advance of our Senegal drilling activities in 2015 we revised our Emergency Response Plan (ERP) to integrate with our well management delegate systems, and likewise aligned and improved the Oil Spill Contingency Plan (OSCP). An ERP was also in place for our seismic activities in Senegal, which completed in 2015. Following a substantial revision of our Crisis and Emergency Response Manual, the Crisis and Emergency Response Team (CERT) – the focal point to support Group crisis management – was revised, briefed and exercised in a variety of crisis and emergency scenarios, including major accident and oil spill. Exercises were carried out on a routine basis to improve and maintain preparedness skills.

Oil spill contingency planning

We invested heavily in memberships to gain access to specialist equipment managed by Oil Spill Response Limited (OSRL) during 2015. These memberships allow access to a toolbox of different response equipment and techniques, including mechanical containment and surface dispersant application systems, sub-sea systems, and aerial surveillance and dispersant spraying capability. Specialist sub-sea equipment includes the Sub-sea Incident Response Toolkit (SIRT), which enables debris clearance and application of dispersant at or near any well releasing hydrocarbons, and also improves mixing and efficiency of treatment and dispersal. This, in turn, improves amenability to biodegradation of spilled oil. We also have access to a Global Dispersant Stockpile, which consists of substantial amounts of commonly used dispersants that can be drawn on should our supplies run out.

Membership of the Capping Stack System (CSS) allows access to well-capping stacks situated at four strategic locations worldwide. These can be deployed to shut-in a well and prevent oil from escaping to sea, at which point sub-sea dispersant is no longer needed. We continue to plan for relief well drilling as an option to address such an event. The nature of the response depends on numerous factors relating to logistics and effectiveness.

Each drilling programme has specifically tailored emergency response plans, which include regional variations. We continue to work extensively with authorities in Senegal, including participation in an International Maritime Organisation workshop on offshore dispersants and a full offshore equipment deployment exercise.

Case study: Oil spill prevention and contingency planning in Senegal

Wherever Cairn operates, oil spill planning starts with detailed prevention activities including well designs that exceed requirements for the expected characteristics of the geological formations to be encountered. All well designs are verified by specialists. In this way, primary and secondary well control is built into the design (see Asset protection and major accident prevention).

In the very unlikely event that both primary and secondary well control barriers prove ineffective, tertiary response methods are employed. In accordance with International Association of Oil & Gas Producers (IOGP) guidance, a number of hydrocarbon release scenarios are examined including the ‘worst credible case discharge’. The latter is used in conjunction with information gathered via the Environmental and Social Impact Assessment (ESIA) to develop an appropriate plan. Our OSCP for Senegal was no exception and this was developed in close consultation with local authorities and in accordance with IOGP guidance. We held a capacity-building session with a variety of stakeholders in 2015, which assisted in raising awareness of response techniques included in the OSCP. The ERP and OSCP were used in producing the ‘Plan d’Opération Interne’ (POI) that formed part of the application for approval process in Senegal.

The OSCP is based on a three-tier response system. Tier 1 is a response to a localised spill close to the operation. Equipment and personnel to respond to a localised spill are located on the rig and the platform support vessels. In Senegal, we deployed an enhanced range of Tier 1 response equipment in Dakar port and on vessels. Selected personnel received specialist International Maritime Organisation (IMO)-approved oil spill training and equipment deployment exercises were run to assess operational readiness.

If an incident requires resources beyond this local Tier 1 capability, resources from Tier 2 are provided from the shore base and from the national capability, where available. In Senegal, we joined the regional spill organisation West and Central Africa Aerial Surveillance and Dispersant Spraying Service (WACAF), which provides capability directly from West Africa and improves response time in the event of a major spill.

In the event that Tier 2 may become overwhelmed, an international oil spill capability can be drawn on (Tier 3). This is achieved via our membership of OSRL. We continue to look for improvements in our capabilities and held logistic workshops and reviews regarding deployment of the CSS and SIRT systems for the Senegal programme.

Unfortunately, we had two very small spills both of less than one litre in 2015, one offshore as the result of flare ‘drop-out’ during testing of the SNE-2 well, and residual waste oil to a surface drain at Dakar port during tank cleaning. In both cases the oil spill was less than one litre and the environmental impact was insignificant.

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