Design and simulation of a lab-scale down-hole drilling system

As global energy demand rises, so does the need for resources and the means to extract them safely and efficiently by means of, for example, down-hole drilling. These large mechanical rigs often encounter lateral, axial, and torsional vibrations which can cause serious equipment damage and possibly failure. To minimize malignant effects, control algorithms are developed and tested on lab-scale models before implementation on large-scale rig systems. Many previous lab-scale systems artificially reproduce vibrations via inertial masses, shakers, braking systems, etc. However, they do not attempt to match the physical properties or natural response of the drill string. The goal of this research is to naturally reproduce a drilling system’s physical behaviors at lab scale through systematic analysis and design. First, a lumped parameter model is used to model the system dynamics. Through nondimensional stiffness ratios, which dictate the drill string material and geometric selection, the drill string’s elastic nature is reproduced. From this selection, the system parameters are further defined by the maximum allowable forces, derived from a bit–rock interaction model and chosen failure criteria. After development of a dynamics model and outline of design constraints, a systematic method of design and simulation of a customizable lab-scale drilling system is proposed.