Drilling With Steerable Motors in Large Diameter Holes

Abstract

Abstract Steerable motor drilling systems, initially used for intermediate and production hole sizes, have evolved to a point of efficient application in large diameter surface holes. These systems combine directional and straight hole drilling capabilities to provide precise directional control. With better directional control, dogleg severity is more precisely determined and is therefore often reduced in the critical surface hole section. A brief summary of steerable systems is given, followed by applications and benefits of using these systems in large diameter holes. Also presented is a section that covers system design considerations when using steerable motors and briefly details a typical bottomhole assembly, surveying methods, and drilling parameters. Finally, a series of case histories, based on successful applications in the Far East and the North Sea, will be presented to demonstrate the range of flexibility possible with steerable systems in large diameter holes.