Ground monitoring of bottom hole assembly vibration in drill string system using acoustic transfer functions and hybrid analytical/two-dimensional finite element method
© 2015 by ASME. When an analytical approach is used to model the vibration of a drill string system (DSS), it is difficult to include detailed modeling information such as the effects of mud or the geometries of complex pipe connections, while a full 3-D numerical approach is extremely expensive due to its large model size to model the long DSS. Here, the Acoustic Transfer Functions (ATFs) identified by using the Hybrid Analytical/Two-Dimensional Finite Element Method (2D HAFEM) are used to estimate the vibration excitation force and torque at the bottom hole assembly (BHA) of the DSS from the acoustic measurements made on the ground. Since the HAFEM uses an analytical wave solution in the axial direction of the pipe, while its response in the cross-sectional directions is represented by using a FE approximation, the HAFEM model is much more computationally efficient than conventional full 3-D models, while it can include the detailed modeling information. For the validation of the BHA vibration monitoring method, full 3-D FE analyses and experiments with a drill string system have been conducted. It is shown that the force and torque estimated by using the HAFEM-based ATF approach match well with the excitation force and torque except resonance frequencies.
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