An observation method for diagnosing drill string stick-slip vibration
A technology of stick-slip vibration and drill string, which is applied in the observation field of diagnosing drill string stick-slip vibration, which can solve problems such as the inability to directly obtain the state of the downhole drilling system, and achieve the effect of improving accuracy and system science
Active Publication Date: 2020-04-10
NORTHWESTERN POLYTECHNICAL UNIV
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Problems solved by technology
[0005] In view of the defects or deficiencies in the above-mentioned background technology, the purpose of the present invention is to provide an observation method for diagnosing the stick-slip vibration of the drill string, which is used to solve the problem that the state of the downhole drilling system cannot be directly obtained in the prior art
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[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.
[0033] Such as figure 1 As shown, in the present invention, the input of the state observer 1 for diagnosing the stick-slip vibration of the drill string is the driving speed ω of the motor 3 1 and the drive torque T of motor 3 m , the output is the estimated speed of motor 3 Torque estimate for drill string 4 and BHA5 RPM estimates To diagnose whether the drill string stick-slip vibration occurs. Wherein, the frequency converter 2, the motor 3, the drill string 4 and the bottom hole assembly 5 form a drilling system, and the drill string 4 and the bottom hole assembly 5 are located underground. The main function of the state observer 1 is to estimate the torque of the drill string 4 and the rotational speed of the bottom hole assembly 5, and further diagnose whether stick-slip vibration of the drill string occurs.
[0034] Such as f...
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The invention discloses an observation method for diagnosing stick-slip vibration of a drilling string. The actual value of the motor drive rotating speed and the actual value of the motor drive torque of a drilling system are used as input, and the motor drive rotating speed, the drilling string torque and the bottom-hole drilling tool assembly rotating speed can be estimated. The observation method comprises the steps that the motor drive rotating speed is directly obtained through a frequency converter of the drilling system, the motor drive torque is directly obtained through the frequencyconverter of the drilling system, a second-order perturbation model is designed to obtain a drilling string torque estimated value, the motor drive rotating speed estimated value is obtained throughthe rotary table dynamics, the bottom-hole drilling tool assembly rotating speed estimated value is obtained through the drilling string dynamics, and a state observer can diagnose whether the stick-slip vibration of the drilling string occurs or not according to the obtained drilling string torque estimated value and the bottom-hole drilling tool assembly rotating speed estimated value. The observation method for diagnosing the stick-slip vibration of the drilling string can diagnose the motion law of a drilling string assembly downhole several thousand kilometers and the magnitude of the drilling string torque.
Description
technical field [0001] The invention belongs to the technical field of petroleum and natural gas exploration and development, in particular to an observation method for diagnosing stick-slip vibration of a drill string. Background technique [0002] The exploration and development of oil and natural gas are mainly completed by the drilling system. Drilling system mainly includes frequency converter, drive motor, drill string and bottom hole assembly, etc. Because the drill string needs to go deep into the ground several thousand meters, the moment of inertia of the bottom hole assembly is small, and the nonlinear friction exists, the drilling system is prone to stick-slip vibration of the drill string. The stick-slip vibration phenomenon of the drill string is mainly manifested in the fact that the drive motor provides a constant torque for the drill string, the motor drive speed vibrates at low amplitude, and the bottom hole assembly appears "slip-stick-slip" alternately. ...
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IPC IPC(8): E21B44/04
CPCE21B44/04
Inventor 付蒙李江红任娇刘科峰马鹏刚宋叔飚张文龙侯媛媛冀晓翔
Owner NORTHWESTERN POLYTECHNICAL UNIV