Drilling: the use of a rig and crew for the drilling, suspension, completion, production, testing, capping, plugging, and abandoning of a well or the converting of a well to a producing well. Also includes any related environmental studies. Associated costs include completion costs but do not include equipping costs.
Rotary drilling: A drilling system in which a rotating bit connected to a hollow drill pipe penetrates a rock formation. Fluid is pumped through the pipe so the rock cuttings can be brought to the surface.
Horizontal drilling: A drilling method whereby a vertical drilling hole is redirected so it is parallel to the oil formation, which can then be penetrated from the top.