# Title (en)

Method and system for detecting bit-bounce

# Title (de)

Vorrichtung und Verfahren zum detektieren von longitudinalen Bewegungen eines Bohrgestänges

# Title (fr)

Méthode et système de détection du déplacement longitudinal d'un outil de forage

FR 9904941 A

# Abstract (en)

At least two values (Rf, Rwob) are calculated in real time. Rf is a function of the principal oscillating frequency of the weight at the bend WOH divided by the speed of rotation. Rwob is a function of the weight on the tool WOB estimated by the model reduce the measured signal of the weight at the bend WOH divided by the mean weight on the tool WOB0 . The method uses a physical model of the drilling process based on general equations for the mechanism and has the following stages: the parameters of the model are determined taking into account the characteristic parameters of the shaft and the drill string; the model is then reduced, keeping only some of the modes of the model matrix. The longitudinal behavior is calculated f the values of Rf and Rwob. The mean weight on the tool WOB0 is defined from the weight of the drill string and the weight at the mean bend. Rf is compared with an interval with milestones chosen so there is no dangerous longitudinal movement if Rf is in the defined interval. If Rf is in the interval, the danger is determined as a function of Rwob. Rf = 20 asterisk fWOH / RPM0, where fWOH is the principal oscillation frequency in Hertz over the interval (0, 10) Hz, and RPM0 is the mean instantaneous speed of rotation at the surface, in turns/min. The milestones for the interval are 0.95 and 0.99. Rwob = Swob/WOB0, where Swob is the weight on the tool estimated from the signal at the mean bend and the model, and WOB0 is the mean weight on the tool, defined from the mass of the drill string and mean bend. For Rwob less than 0.6 there is no danger; for Rwob between 0.6 and 0.8 there is a medium danger and for Rwob greater than 0.8 there is extreme danger. Independent claims are also included for a system for applying the above method and the application of the method to determining the danger of drill string dysfunction by jumping.

# Abstract (fr)

La présente invention concerne un système et une méthode de génération d'alarme sur le comportement longitudinal effectif d'un outil de forage fixé à l'extrémité d'une garniture de forage entraînée en rotation dans un puits par des moyens d'entraînement situés en surface, dans laquelle on utilise un modèle physique du processus de forage fondé sur des équations générales de la mécanique. On effectue les étapes suivantes: on réduit le modèle pour ne conserver que les modes pertinents, on calcule au moins deux valeurs Rf et Rwob, Rf étant une fonction de la fréquence principale d'oscillations du poids au crochet WOH divisée par la vitesse de rotation instantanée moyenne en surface, Rwob étant une fonction de l'écart-type du signal de poids sur l'outil WOB estimé par le modèle longitudinal réduit à partir de la mesure du signal de poids au crochet WOH, divisé par le poids sur l'outil moyen WOB0 défini à partir du poids de la garniture et du poids au crochet moyen; On détermine la dangerosité du comportement longitudinal dudit outil de forage à partir desdites valeurs de Rf et Rwob. <IMAGE>

# IPC 8 full level (invention and additional information)

E21B 44/00 (2006.01)

# CPC (invention and additional information)

E21B 44/00 (2013.01)

# Citation (search report)

• [A] FR 2750159 A1 19971226 - INST FRANCAIS DU PETROLE [FR]
• [A] FR 2720439 A1 19951201 - INST FRANCAIS DU PETROLE [FR]
• [A] P.J. PERREAU ET AL: "new results In Real Time Vibrations Prediction", SPE # 49479, 11 October 1998 (1998-10-11), pages 190 - 200, XP002126257
• [A] V.S. DUBINSKY ET AL: "An Interactive Drilling Dynamics Simulator for Drilling Optimization and Training", SPE # 49205, 27 September 1998 (1998-09-27), pages 639 - 648, XP000863185
• [A] HENNEUSE H: "SURFACE DETECTION OF VIBRATIONS AND DRILLING OPTIMIZATION: FIELD EXPERIENCE", IADC/SPE # 23888, 18 February 1992 (1992-02-18), pages 409 - 423, XP002059287
• [A] J.W. NICHOLSON: "An Integrated Approach to Drilling Dynamics Planning, Identification and Control", IADC/SPE # 27537, 15 February 1994 (1994-02-15), pages 947 - 960, XP002125005

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