DROPS Incident Review Control Line Sheave Fell 4

DROPS Incident Review: Control Line Sheave Fell 4 Meters to Rig Floor (Pot 4 B) Location: Noble Roger Lewis - QSGTL Date: March 3, 2010 Incident: 485866 What Happened: At 16: 30 while RIH with the 7” completion, the Halliburton TRSSSV control line sheave fell onto the rig floor. This was due to the sheaves eyebolt-retaining nut backing off, allowing the sheave that weighed 48 Lbs (22 kg) to drop to the floor. The sheave was suspended from the rig floor hydraulic hoist at a height of 12’ (4 M) above the rig floor. The sheave was certified (14/01/2010) and had passed the onshore QA/ QC inspection on the 31/01/2010 (potential for dropped object was not identified) Initial Observations l No securing/ retaining or locking devices to prevent the nut from backing off. l Grease nipple painted over preventing proper maintenance of the pin Initial Recommendations: 1) Non compliance to DROPS standards 2) Ensure QA/QC inspection standards comply with DROPS prior to mobilizing to rig site 3) Review maintenance (PMS) of contractor equipment used at height Piston Down-Stop Allen Screw

EPT-Wells Incident Review: Tree Actuator Uncontrolled Spring Tension Release Location: Qatar Shell Pearl-1 Platform Date: March 28, 2009 Incident: 346439 What Happened: During a tree actuator strip down (as part of the well suspension programme), the outer can of the actuator was removed, exposing the actuator springs. These springs are removed by slowly backing out the spring retainer plate, until all spring tension is released (46 turns). A further 8 turns will unscrew the retainer plate completely and the springs can then be removed without tension. However, while backing out the spring retainer plate, the piston down-stop also backed off. By design this down-stop should stay in place, secured with 2 Allen screws. After the initial 7 turns the down-stop was fully unscrewed and as a result the spring and retainer plate was ejected under tension, landing ~8 meters away from the tree (striking a scaffold platform on its path). Nobody was injured as the risk of an uncontrolled spring tension release was identified and no personnel was positioned in front of the actuator. Initial Root Causes l Piston down-stop Allen screws not engaged properly (confirmed tight before spring removal but not all the way in) l Difficult to notice piston down-stop movement while backing out spring retainer plate, especially with springs installed Actuator Position Main learning points/ Actions: 1. Physically verify piston down-stop Allen screws are fully screwed in, prior to spring retainer plate removal (perform dimensional check) 2. Continuously monitor for piston down-stop movement by installing a ‘flag’ in an Allen screw hole. This ‘Flag’ protrudes to above the springs and unintentional rotation of the down-stop should be noted immediately Spring Piston Down-Stop Spring Retainer Plate Allen Screw