Importance

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Abstract

A sonic damper unit which is placed directly above a drill collar string to damp out unwanted complex wave vibrations of the string both longitudinal and lateral in vibration mode. The damper unit comprises a tubular section which is filled with small pieces of material trapped therein which may comprise pellets of metal, pebbles, ceramic, etc. A longitudinal channel may be formed within the tubular damper unit for transporting mud therethrough and to be mixed into the trapped pellets or the like. The damper unit is preferably located in a low impedance region of the standing wave pattern formed in the string some distance from the bit, e.g. the top of the drill collar string. The pellets are capable of motion in a random pattern and thus effectively respond to the frequency content of complex vibrational wave modes both lateral and longitudinal and effectively damp out any such unwanted vibrational energy which may appear in the drill collar string.

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First Claim