SteveSS
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I took a chance and bought the DEEPWATER HORIZON DVD last night. Being in the oil business as a well-site geologist I was interested in the drilling rig aspects of the movie. I was hoping it was not all about dead seabirds and oil slicks and it is not. It's about the rig and the explosion.
Some of these are spoilers so beware. I wanted to explain some of the technical data used in the film.
DH was nearing the end of the drilling/exploration section of the well. When you first drill a well you drill a larger hole to x amount of depth then set surface casing. Then you push concrete down the casing and around the outside of the casing pipe. This hardens and cuts off communication with the rock beds around it. You'll see a quick model of this in the movie. They talk about a cement bond log in the movie. This checks the cement job to make sure it's secure. After this is done, you drill the well with smaller drill pipe and the casing remains in place forever.
The drill bit is bigger than the drill pipe. This creates an annular space outside the drill pipe and the hole. The drilling mud is a mixture of lots of chemicals but it's weight and viscosity is constantly measured. It is pumped down the drill pipe, through the bit then back up the outside of the pipe in the annular space. When you reduce the weight of the mud you are letting the pressure of the well push against the mud. Even if you have heavy mud you can still have a blow out if the gas is under more pressure than the weight of the mud.
I don't know why their BOP blow-out-preventer failed but it did. In this case you have rocks, gas and oil blowing to the surface. I've been on a blow-out before. All the mud comes blowing out of the hole then debris and gas. We just turned everything off and left for it two days and it blew itself out. Luckily nothing sparked an explosion. This still happens when you hit shallow gas before you set your surface casing. Rigs burn to the ground every year.
There's a million ways to be killed working on an oil rig. The workers all know it.
Some of these are spoilers so beware. I wanted to explain some of the technical data used in the film.
DH was nearing the end of the drilling/exploration section of the well. When you first drill a well you drill a larger hole to x amount of depth then set surface casing. Then you push concrete down the casing and around the outside of the casing pipe. This hardens and cuts off communication with the rock beds around it. You'll see a quick model of this in the movie. They talk about a cement bond log in the movie. This checks the cement job to make sure it's secure. After this is done, you drill the well with smaller drill pipe and the casing remains in place forever.
The drill bit is bigger than the drill pipe. This creates an annular space outside the drill pipe and the hole. The drilling mud is a mixture of lots of chemicals but it's weight and viscosity is constantly measured. It is pumped down the drill pipe, through the bit then back up the outside of the pipe in the annular space. When you reduce the weight of the mud you are letting the pressure of the well push against the mud. Even if you have heavy mud you can still have a blow out if the gas is under more pressure than the weight of the mud.
I don't know why their BOP blow-out-preventer failed but it did. In this case you have rocks, gas and oil blowing to the surface. I've been on a blow-out before. All the mud comes blowing out of the hole then debris and gas. We just turned everything off and left for it two days and it blew itself out. Luckily nothing sparked an explosion. This still happens when you hit shallow gas before you set your surface casing. Rigs burn to the ground every year.
There's a million ways to be killed working on an oil rig. The workers all know it.
