04958125 is referenced by 60 patents and cites 5 patents.

The invention is related to a method of determininng the instantaneous rotation speed of a drill string or a drill bit in a borehole or the lateral shocks applied to the string or bit. The centripetal acceleration of the drill string is measured at at least two opposite ends of a drill string diameter so as to obtain two centripetal acceleration signals ac1 and ac2; the signals ac1 and ac2 are combined and the instantaneous rotation speed or the lateral shocks are derived from said combined signal. The accelerometers must be of the type delivering a signal with a DC component. An important application of the invention is to transform drill string rotation speed dependent data acquired versus time with a constant sampling time increment T.sub.c separating successive data, into compensated data which would be obtained for a substantially constant drill string rotation speed S.sub.c. The compensated data are obtained either by adjusting the constant sampling time interval T.sub.c into a variable sampling time increment T.sub.v, using the measured instantaneous rotation speed S, or by selecting the data which have been acquired during periods of time during which the instantaneous rotation speed of the drill string varied within predetermined limits only.

Title
Method and apparatus for determining characteristics of the movement of a rotating drill string including rotation speed and lateral shocks
Application Number
7/441683
Publication Number
4958125
Application Date
November 22, 1989
Publication Date
September 18, 1990
Inventor
Marc Lesage
Missouri City
TX, US
Dominic McCann
Paris
FR
Stuart Jardine
Cambridge
GB
Agent
John J Ryberg
Assignee
Anadrill
TX, US
IPC
E21B 47/00
G01P 15/00
G01P 3/42
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