Institut Francais Du Pe'trole

Institute Francais Du Petrole

Jean-Pierre Desplans

Claude Mabile

Didier Pavone

Isabelle Rey-Fabret

Isabelle Fabret

The present invention is a system and method for generating an alarm relative to effective longitudinal behavior of a drill bit fastened to the end of a drill string driven in rotation in a well by a driving device situated at the surface, using a physical model of the drilling process based on general mechanics equations. The following steps are carried out: the model is reduced so to retain only pertinent modes, at least two values Rf and Rwob are calculated, Rf being a function of the principal oscillation frequency of weight on hook WOH divided by the average instantaneous rotating speed at the surface, Rwob being a function of the standard deviation of the signal of the weight on bit WOB estimated by the reduced longitudinal model from measurement of the signal of the weight on hook WOH, divided by the average weight on bit WOB , defined from the weight of the string and the average weight on hook. Any danger from the longitudinal behavior of the drill bit is determined from the values of Rf and Rwob.

Method and system for detecting the longitudinal displacement of a drill bit

The present invention relates to a system and to a method designed to estimate the effective displacement of a drill bit fastened to the end of a drill string and driven into rotation in a well by surface driving means. A non-linear physical model of the drilling process based on general mechanics equations is used in the invention. The following stages are performed in the method:

Method and system for real-time estimation of at least one parameter

The present invention relates to a system and to a method designed to estimate the effective behaviour of a drill bit fastened to the end of a drill string and driven into rotation in a well by surface driving means, wherein a non-linear physical model of the drilling process based on general mechanics equations is used. The following stages are performed in the method:

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Saint Germain Les Corbeil, France

Jean-Pierre Desplans