Pulsing Mud Communication System

No we are not talking about the deliberate obfuscation of communication of the MUD people in Dilbert's cartoons.

When you are three thousand feet in the ground, the temperature is 200 C, the pressure is 20000 psi and you need to tell people what it is like to be down there. Well this is exactly the problem the folks in oil drilling face everyday. If you consider that drilling cost about 200 to 300 K$ a day, you want to have a better solution than just going ten feet with some pole, pulling it back out, check the soil it witnessed and iterate until you get to 3000 meters down. The solution was devised by Schlumberger as Logging While Drilling (LWD): in short they put a probe next to the drill and expect the probe to send info back up. The probe has nuclear materials, NMR capabilities and so on and it is pretty expensive.

So how do you send information back up from deep down ? Wi-Fi or RF Comms won't work because of the depth of the rock. Resistivity or something equivalent like sound along the poles ? It turns out most of these poles are crunched by the pressure once they are down, so the ideal measurements of conductivity you knew don't work deep into the ground: It is a very bad inverse problem. Schlumberger came up with an innovative means, use the water they send down to help the drill convey messages back to the communication station. When it comes back up, that water is mud. So the probe sends pulses through the water/mud and convey information back up. The data rate is astonishing too: 15 bits/second.