E - Fixed Constructions – 21 – B
Patent
E - Fixed Constructions
21
B
E21B 44/00 (2006.01)
Patent
CA 2745062
A method of estimating the instantaneous rotational speed of a bottom hole assembly (16) at the lower end of a drill string (12) that is driven by a drilling mechanism (30) at the upper end of said drill string (12), and which drill string (12) is suspected of suffering stick-slip oscillations that have an estimated or observed fundamental frequency, which method comprises the steps of determining variations in a drive torque of said drilling mechanism (30), combining a known torsional compliance of said drill string (12) with said variations in a drive torque, and providing an output signal representing said instantaneous rotational speed.
L'invention concerne un procédé permettant d'estimer la vitesse instantanée de rotation d'un ensemble en fond de trou de forage (16) à l'extrémité inférieure d'un train de tiges de forage (12) qu'entraîne un mécanisme de forage (30) à l'extrémité supérieure dudit train de tiges de forage (12), ce train de tiges de forage (12) étant susceptible d'effectuer des oscillations saccadées ayant une fréquence fondamentale estimée ou observée. Le procédé consiste à déterminer les variations de couple d'entraînement dudit mécanisme de forage (30), combiner une élasticité torsionnelle connue dudit train de tiges de forage (12) auxdites variations de couple d'entraînement, et fournir un signal de sortie représentant ladite vitesse instantanée de rotation.
Kyllingstad Aage
Nessjoen Paal Jacob
Mcfadden Fincham
National Oilwell Varco L.p.
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