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AssigneeInstitute Francais du Petrole
InventorsIsabelle Fabret, Claude Mabile, Jean-Pierre Desplans
Estimating the term…
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: the parameters of said model are identified and computed by taking account of the parameters of said well and of said string, said model is linearized about a working point, said linearized model is reduced while keeping only some of the specific modes of the state matrix of said model, the displacement of the drill bit or the stress applied to the bit is computed in real time by means of the reduced model and of at least one parameter measured at the surface. FIG. 4 to be published.
A method for estimating the effective longitudinal 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, said well having physical parameters, said method comprising the steps of:
A system for estimating the effective longitudinal behavior 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 computing unit comprises means for a non-linear physical modeling of the drilling process based on general mechanics equations and represented by a state matrix in specific modes, characterized in that parameters of said modeling means are identified by taking into account parameters of said well and of said string, in that the computing unit comprises means designed for linearization of said model about a working point, means for reducing said linearized model so as to keep only the pertinent modes of the state matrix of said model, means for real-time computation of the vibratory longitudinal displacement of the drill bit or of the stress applied to the bit, by means of the modeling means once linearized and reduced, and means for measuring at least one parameter linked with the displacement of the string at the surface.
Dependencies are inferred from the claim text.