Drillsafe. Learning From Incidents. 29 August Roger Fletcher Health Safety Environment. Shell Development Australia

Transcription

1 Learning From Incidents Drillsafe 29 August 2007 Roger Fletcher Health Safety Environment 1 - SEAAOC 18 June 2001

2 Background Significant challenges with offshore support vessels 25% of exposure hours 70% of recordable injuries Incident 17 April 2007: Broken chain during Anchor handling Minor injury to crew member (bruising while taking evasive action) Potential consequence: significant injury or fatality Detailed incident investigation using Tripod 2 - SEAAOC 18 June 2001

3 Location of the injured person 3 - SEAAOC 18 June 2001

4 Event 1: Winch breaks on Lewek Swift Incident modelled using Tripod : 1. What happened? (sequence of events) 2. What barriers / controls failed? 3. Why did those barriers / controls fail? Hazard Operation of the Winch Immediate failure Precondition Underlying failure Failed Barrier Correct winch operating procedures followed Work winch breaks on Lewek Swift and restricts its anchor handling ability Event becomes the new hazard Lewek Swift Anchor Winch Target 4 - SEAAOC 18 June 2001

5 Initial anchor handling set up Wind Southerly #6 anchor Rig Heading 206 Current NE 2 to 4 knots Epoch Bridle #2 anchor on Swift L Swift 5 - SEAAOC 18 June 2001 L Shell Emerald Development Australia

6 Modified anchor handling set up Wind Southerly #6 anchor Rig Heading 206 Current NE 2 to 4 knots Epoch FWD #3 anchor on Emerald Well Location #2 anchor on Swift 6 - SEAAOC 18 June 2001

7 Sequence of events Event 1: Winch breaks on Lewek Swift Event 2: Decision to remove L.Emerald from tow bridle to run anchors (repositioning of rig required) Event 3: Excessive movement of vessel relative to chain and rig creates a shock load Event 4: Chain breaks on L. Emerald Event 5: Injury to 2 nd officer (High Potential) 7 - SEAAOC 18 June 2001

8 Failed Barriers Event 1: Winch operating procedures Event 2: Change control process for the operation Event 3: Vessel movement controlled Controlled payout/pickup of anchor chain Event 4: Sufficient catenary to absorb loads Emergency Release of Drum Integrity of work wire assembly (improvement) Event 5: Rear deck clear of all personnel Effective barrier- bollard protection/ crash rail 8 - SEAAOC 18 June 2001

9 Detailed Tripod Analysis Tree Inadequat e vessel spe cific t raining for winch operations Lack of competence in winch operating procedures V e sse l spe cific procedures for operating winch not followed by the operator Operation of the Winch Correct winch operating procedures followed Work winch breaks on Lewek Sw ift and restricts its anchor handling ability Inadequate discussion, and review of the changed operation by all part icipants prior t o starting Agreed communication protocol not in place between vessel & rig Barge master expects vessel to slow & stop as brake applied Ineffective radio communications between vessel & rig (instructions not confirmed) Rig pays out extra 300' chain and applies brakes (incompatable w ith vessel speed) Lewek Swift Anchor Winch Decision to release the Emerald from tow bridle t o run anchors & reposition rig (changed risks) Cat e nary calculat ion not required of vessel master prior to starting operations Close proximity of vessel / lack of available catenary to absorb movement Insufficient time to respond and release drum Emergency drum release not activated by operator Robust change control process Controlled pay out and pick up of anchor chain Lewek Emerald Excessive movement of ve sse l re lat ive t o chain and rig creates shock loads sufficient catenary to enable chain to absorb excessive movement Emergency release of load on drum Inade quacie s in init ial rig move plan, documentation, meeting & minuting Assumptions made that all part ies fully understand the operations Change control process and decision making does not involve all parties Vessel movement controlled Work wire chain link breaks on Lewek Emerald Lewek Emerald Lack of more thorough discussion of the changed operation Rig move marine specialist role under utilized (incompletely defined) with respect to boat operations Incomplete understanding of risks of changed operations Inadequate discussion, and review of the changed operation by all part icipants prior t o starting Vessel at 30% power based on captain's misconception that rig is ho lding t he t ensio n on chains Vessel does not hold constant tension on the chanin W ork w ire chain W ork w ire & chain asse mbly inte grit y (improvement) Bollard & crash rail protection at starboard quarter of boat Po t e nt ial se rio us injury or fat alit y (minor injuries received) Lack of alignment bet w een cont ractors on desired pendant length and drum wrapping practices Inspection of equipment by Rig move marine spe cialist not required or carried out Marine procedures do not set minimum standards for assembly Partly w rapped chain on drum results in twisted chain V arying link and shackle sizes and ratings used in assembly Poor chain wrapping and assembly practices on boat compromises assembly integrity 2nd mate (at Starboard Quarter) Practice established where anchor orientation is checked from boat rather than rig at night Deficiencies in application of anchor handling procedures Rear deck of boat clear of all personnel Anchor is often not oriented the right way up & requires checking 2nd mate at starboard quarter behind bollard checking anchor orie ntat ion Inadequat e communications & lack of line of sight (barrier obst ructs view ) Vessel master unaw are 2nd mate w as at rear of boat Cult ure o f int e rvent io n/ "stop the job" not in place 9 - SEAAOC 18 June 2001

10 Actions taken support vessels Vessel operators trained in winch specific operations Catenary calculations to be made by vessel master Anchor chain to be off the drum and minimum standards set for vessel pendant assembly Shell Marine Captain to do vessel equipment inspection prior to use Procedures enhanced to improve anchor orientation Additional process step to verify deck is clear of personnel Re emphasize stop the job message 10 - SEAAOC 18 June 2001

11 Actions taken rig move operations Earlier Rig move meeting scheduling > 24 hours, involve both masters; minuted; checklist followed Content of rig move meeting improved Early issue of documentation ahead of rig move meeting Master and barge captains to agree any changes to operations Communication protocol agreed and documented Rig to verify anchor orientation Improvements to rig anchor chain drum braking mechanism 11 - SEAAOC 18 June 2001

12 Outcomes Robust actions implemented by marine contractor to address root causes & improvements Strong support & steps implemented by drilling contractor to strengthen rig move operations Three successful, incident free rig moves 12 - SEAAOC 18 June 2001