Development of a Novel Hybrid-Type Rotary Steerable System for Directional Drilling
Unlike conventional resources, unconventional resources, such as shale gas and coal bed methane, are situated horizontally under geological formations. To exploit these resources, directional drilling and hydraulic fracturing technologies are required. In directional drilling, the dog leg severity (DLS), which indicates how much the angle changes while drilling 100 ft, is a major issue with respect to the cost and time of drilling. In this paper, we briefly review different types of directional drilling methods and propose a new hybrid-type rotary steerable system (RSS). DLS calculations based on three-point geometry for these systems are suggested. This hybrid RSS combining two conventional types of RSSs: point-the-bit and push-the-bit systems, achieves better steerability. The hybrid mechanism is implemented using hybrid pads with hydraulic cylinders and a spherical joint. The advantages of the proposed system are demonstrated by performing small-scale prototype and cement block drilling tests.
Hybrid 4-pad rotary steerable system for directional drilling of unconventional resources
As the importance of unconventional resource grows, the demand for the directional drilling technology is increasing. One of the key technologies of the directional drilling is a rotary steerable system (RSS). Among several types of RSS developed so far, `point-the-bit' and `push-the-bit' are the most commonly used ones. In this paper, a new rotary steerable system using hybrid 4-pad system is introduced. This mechanism improves the steering angle by taking advantages of both `point-the-bit' and `push-the-bit' types. We describe the detailed structure and kinematics of this system.
Time and Heritage
As a historian studying what can be considered a form of intellectual history, I have slowly come to adopt Michel de Certeau’s observation made at the end of the 1980s that ‘objectifying the past, for the last three centuries, has undoubtedly left unconsidered time within a discipline that has continued to use it as a taxonomic instrument’. To a certain degree, time has become commonplace for the historian who has preserved or instrumentalized it. It is not considered because it is inconceivable, but because we do not think of it or, more simply, we do not think about it. As a historian attempting to pay attention to the time I’m living in, I have thus, like many others, noticed the swift development of the category of the present until it has become obvious that the present is omnipresent. This is what I refer to here as ‘presentism’.