Elgin G4 Gas Release: What Happened and the Lessons to Prevent Recurrence

Abstract

Abstract The Elgin installation is located in the North Sea, approximately 200km east of Aberdeen, Scotland. The facilities consist of a Process, Utilities and Accommodation platform with a bridge linked WellHead Platform (WHP). On 25th March 2012, Well G4 on the WHP suffered an uncontrolled release of hydrocarbons to atmosphere. This release resulted in the full evacuation from the Elgin installation and from the adjacent drilling rig. Immediately following the release, significant resources were put in place to ensure that the required emergency response was effectively managed and implemented. These resources managed both the initial response and evacuation, and the ongoing on-site situation until well control specialists killed G4 with heavy mud on 15th May 2012. Significant preparatory work was required to pump heavy mud into G4. This included detailed hazard assessment of the gas release, and the potential consequences should it have ignited. It also included carrying out risk assessments for each stage of the recovery to ensure the safety of personnel. Following the well kill operation, routine personnel returned to the installations to secure G4 with cement, and to prepare for the re-start of production. Production re-started from Elgin on 9th March 2013, following a comprehensive re-assessment of the risks from the wells. This re-assessment involved demonstrating that the risks from the wells to personnel are reduced to a level which is As Low As Reasonably Practicable, and was formally assessed by the UK regulatory authorities via the "Safety Case". This paper focuses on what happened, the lessons learned and the measures put in place to prevent recurrence. More specifically, this paper will describe: the incident, in terms of the uncontrolled hydrocarbon release which occurred, the associated leak path and the emergency responsethe work associated with killing G4 with heavy mudthe incident investigation carried out and the associated causesthe action taken to ensure that lessons have been learned to prevent recurrencethe re-evaluation of well integrity, and development of well integrity "criteria"returning the offshore facilities to a fit for purpose condition to allow production to be restartedthe role of the Safety Case and how it was used to demonstrate to the UK regulatory authorities, and to the workforce that production could be safely restarted.