Inspection Detail

Inspection: 307816330 - Nabors Drilling Usa Lp

Inspection Information - Office: Wyoming Department Of Workforce Services - Osha Division

Investigation Summary

Rig workers were in the process of changing out a saver sub, which is a section of pipe positioned between the Kelly and pipe. At this time, the depth of the hole was 11,908.2 ft. During the process of adding a section of pipe the evening tower crew dropped the pipe string about six feet. After picking up the pipe string and setting the Kelly, drilling commenced for approximately 100 feet. Because the pipe string was dropped, the decision was made to trip the hole and check the "bottom-hole assembly" bit and mud motor. After tripping to 4,289.8 ft, the chain on the input sprocket for the draw works became loose breaking teeth on the sprocket and shutting down the operation. The sprocket had to be replaced before drilling operations could continue. With the sprocket replaced, the Pusher was on the brake handle and picked up on the slips to see if the pipe would move. It would not. He estimated the down-hole string weight was approximately 150,000 pounds. They could pull up to 70 percent of the string weight. The rotary transmission was placed in low, low/forward, with the table rotating in a clockwise direction. They picked up the pipe string and pulled to 220,000 pounds, rotating the rotary clockwise while attempting to drill through the stuck position. This procedure was not only stretching the drill pipe but also twisting and coiling it as well. The attempt to drill through the stuck position was not successful. The crew had the pipe string in the slips and then rotated (counter-clockwise) untwisting the pipe string. The Pusher picked up on the Kelly to change the saver sub that had pulled threads from the previous hole. Once the new sub was placed in the pipe string, Employee #1, the driller, went into the doghouse to get the chain tongs. The chain tong was fitted with a 37-in. handle and is designed to grip pipe in either direction. Returning to the drill floor, Employee #1 placed the chain tong on the saver sub to tighten it up. The assistant driller raised the Kelly approximately 3-in. to 4-in. above the saver sub, to make it easier to tighten the sub to the pipe string. When Employee #1 began to tighten the saver sub to the pipe string, the pipe string began to uncoil (counter-clockwise) at a very high rate of speed. While Employee #1 was holding onto the handle of the chain tong, he was lifted from the drill floor and forced backwards into the draw works causing him to loose his grip on the handle. Employee #1 began falling to the drill floor. As the pipe was uncoiling, the handle on the chain tong struck Employee #1 several times to the body and head before reaching the drill floor. Employee #1 was transported to the hospital where he died.

Keywords: CHAIN, FRACTURE, DRILL PIPE, OIL WELL DRILLING, KELLY BUSHING, STRUCK BY, TONGS