Method system and apparatus for reducing shock and drilling harmonic variation

摘要

A downhole device comprising a mandrel suitable for connection to a drilling assembly, a housing surrounding the mandrel with the housing being suitable for connection to the alternate end of a drilling assembly and a compensating mechanism configured to adjust an axial force applied to said mandrel by changing the relative position of the mandrel with respect to the housing.

主权项

1. A downhole device suitable for connection to a drilling assembly at its distal end, the downhole device comprising:
a mandrel, a housing surrounding said mandrel, a point of torque transfer between the mandrel and the housing, and a compensating mechanism being at the point of torque transfer, the compensating mechanism comprising a sleeve element configured to adjust an axial force applied to said mandrel and sleeve element by changing the relative position of the mandrel and sleeve element with respect to the housing at the point of torque transfer and through interaction of a primary damping means upon the sleeve element subjected to compression by at least one pre-loaded compression spring at the point of torque transfer, and wherein said compensating mechanism further comprises a secondary damping means which is variable in situ to alter the natural frequencies of the device in order to responsively damp oscillatory motion over one or both of a range of input frequencies and amplitudes and which comprises fluid displacement means.