Drilling for Oil

Quite a few years ago I got to visit, spend the night on, a floating oil drilling platform in the Gulf of Mexico. Some of what I experienced and learned is relevant to helping understand current events. We got to the platform by helicopter from Galveston TX. On the ride out I got to sit across from the pilot.This was my first helicopter ride. It was kind of spooky looking down at your feet and seeing the gulf through the plastic bubble. After that it was kind of boring so I sat and watched the instrument panel. The fuel gauge kept going down. At about half a tank of fuel left the pilot must have noticed me eying the fuel gauge because he said “Don’t worry there is fuel on the platform.” Finally at about a quarter tank the pilot got excited and started checking things. Then he made a 90 degree turn and continued flying. It turns out he had followed the wrong path to the platform and we were about to pass it way to one side. We finally arrived at the platform with less than one eighth of a tank of fuel. First thing after we arrived was a safety briefing including how to get to the life boats.

All the while I was on the platform they were fighting a potential gas blowout. The drilling had come into a layer with gas. The drilling was stopped and they were trying to seal off the gas. This is done by pumping the drilling mud down the well and moving the drill string up and down to try and force the mud into the pores in the rock to seal off the gas. Every time they would lift the drill string the inertial of the string would cause the entire platform to dip down, a bit like an elevator starting down. That was a bit unnerving at first. Especially in light of what they had told us about gas blowouts. If a gas blowout occurs under a platform it is possible that the gas can reduce the density of the water such that the platform no longer floats. It will not sink like a ship slowly filling with water but more like a rock. The life boats on an oil platform are not really boats but more like and escape pod. Considering that if the platform sinks due to a gas blow out a life boat is not going to float either. Hopefully a sealed capsule would eventually drift out of the gas plume and then float to the surface. While trying to seal off the gas the only thing that is keeping the well from blowing out is the weight of the drilling mud in the drill string. A complication to this is that the gas dissolves in the mud much like carbonation is a soda. When the mud rises to the surface the pressure drops and the gas can come out of the mud in bubbles. This reduces the weight of the mud which could eventually result in the mud not having enough weight to keep the gas down. The condition of the mud coming back up the drill string was being constantly monitored by measuring its specific gravity. This was announced on a speaker system to the entire crew. So all day and night you kept hearing “Mud coming up” and some specific gravity number. I suppose the idea was that the smaller the number to more worried you should be. When we left the next day they were still running the string up and down and pumping mud.

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