Here’s Mud In Yer Eye! (or, more on how exactly an oil will is drilled…)

Heading Out writes: Today I thought I would again take a little time off from which country is producing what, and talk again about drilling oilwells. Last time, I wrote about physically breaking the rock. In most cases, this is carried by pressing a series of small teeth set in rings around the perimeter of three cones that rotate around the bottom of the borehole, and that are attached to the bottom of the drill string. (picture here and as a timeline development picture here).

The cones are mounted with their largest diameter running around the outside of the hole, and thus each cone will have the greatest number of teeth along that edge. We call the outside edge of the hole the gage, and the three cones, bearings and mounts combine to form the drill bit.

Now if we just turned the bit round and round in the hole, it would start to drill into the rock, but after a short while the chips and crushed rock would fill up all the space between the bit and the solid rock, and the bit could go no further. We have to get the crushed rock out of the way, and preferably before it is crushed by the following bit tooth since that would waste energy.

(A lot more rock geek speak after the jump at The Oil Drum.