Rotary steerable system
A rotary steerable system (RSS) is a form of drilling technology used in directional drilling. It employs the use of specialized downhole equipment to replace conventional directional tools such as mud motors. They are generally programmed by the measurement while drilling (MWD) engineer or directional driller who transmits commands using surface equipment (typically using either pressure fluctuations in the mud column or variations in the drill string rotation) which the tool responds to, and gradually steers into the desired direction. In other words, a tool designed to drill directionally with continuous rotation from the surface, eliminating the need to "slide" a mud motor. The first known patent application is from Christopher G. Cross in 1873 for "Drills for Boring Artesian Wells", followed in 1884 by the brothers Morris and Clarence Baker for a "Machine for Operating Drills" The methods used to direct the well path fall into two broad categories, these being “push-the-bit” or “point-the-bit”. Push-the-bit tools use pads on the outside of the tool which press against the well bore thereby causing the bit to press on the opposite side causing a direction change. Point-the-bit technologies cause the direction of the bit to change relative to the rest of