Abstract
During drilling process, substantial amount of vibration and shock are induced to the drill string. Active vibration controlled drilling is introduced to reduce the vibration and increase the efficiency of drilling process. In this system, two main components that determine the damping coefficient are magnetorheological (MR) damper and spring assembly. Performance of vibration damping system is depending on the viscosity of MR fluid in the damper and spring constant of spring assembly. One of the key issues that are unclear from the design is the correlation between the axial spring stiffness configuration and the damping force which needs to be tuned actively. There has been lack of studies on how the viscosity of MR fluid on the active vibration damper affects the damping stiffness of the whole system. The objective of the project is to extract the correlations for the viscous damping coefficient, equivalent spring stiffness and power input to the system. Simplified vibration model is thus created using Simulink, together with experimental data fed from APS Technology’s in-house team. Inputs of the simulation such as force exerted, mass of mandrel, spring constant and step time are based on the experimental data and can be adjusted to suit different experiments. By having the model, behavior of the system can be studied and analyzed. From the simulation, it is also observed that the relationship between damping coefficient and power input of the system is linear.
Highlights
During drilling process, substantial amount of vibration and shock are induced into the drill string
Performance of vibration damping system is depending on the viscosity of MR fluid in the damper and spring constant of spring assembly [3,4,5]
Simulation is ran with input data from APS technology such as force applied, mass of mandrel, spring constant and step time [3,4]
Summary
Substantial amount of vibration and shock are induced into the drill string. Drill string is under some heavy and complex dynamics loadings, caused by different sources such as rotation of drill bit, pumping drilling mud, and misalignment of drill string. By producing different state of stresses, these loads may result in excess vibrations and lead to failure of the drilling tools. Three forms of vibrations have been identified for drill string, namely are axial, torsional and lateral vibrations. Magnetorheological (MR) damper in active vibration controlled drilling is introduced to improve the efficiency of drilling process. Viscosity of MR fluid in the damper changes within milliseconds with the presence of magnetic field. Excessive downhole vibrations can be reduced by adjusting the magnetic field which MR fluid passes [2]
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