The principle of rotary screw air compression is really no different than reciprocating (piston) compression. Both are positive displacement machines that take in a fixed volume of air at atmospheric press.
[pdf] There are two separate but closely related parts of preparing for a drilling project—planning the well and designing the well. “Planning” means to list, define, schedule, and budget for all the multitud.
[pdf] Electric generators powered by large diesel engines (the prime movers) generate electricity that move the heavy rig equipment such as the rotary table (or top drive), mud pumps and drawworks. Electric drill rigs are more expensive than mechanical rigs, but offer some nice advantages in return.
[pdf] 
