Dynamic Evaluation of CDS Tensioners

摘要

The Dynamic Test and Analysis Group (DTAG) recently completed a pilot study for the Field Operations System Analysis Group (FOSAG). The purpose of this study was to determine the feasibility of using Modal Analysis to detect damage or structural changes in the Cable Downhole System (CDS) tensioners that could arise from event related excitation or transportation loads. The modal testing revealed that a typical tensioner unit possesses 3 major modes below 25 Hz. One of these modes is a rigid body mode located around 15 Hz with damping between 1 to 2% critical. By using a simple single degree of freedom analysis we were able to directly relate this mode to the structural integrity of the tensioner load cell. In addition, shifts in the resonant frequency of this mode can be directly correlated to changes in the load cell spring stiffness. (ERA citation 11:005273)