Incipient Regimes of Drill Bit Whirlings on Uneven Bottoms of Deep Bore-Holes
Вантажиться...
Дата
2016
ORCID
DOI
Науковий ступінь
Рівень дисертації
Шифр та назва спеціальності
Рада захисту
Установа захисту
Науковий керівник
Члени комітету
Видавець
NTU "KhPI"
Анотація
This paper studies the problem of whirl vibrations of rotating drill string bit under conditions of its contact
interaction with the bore-hole bottom surface. The destructive effects of whirl vibrations of drill bits and drill
strings have long been recognized. The backward whirling is believed to randomly happen to some degree in
40% of all wells.
It is shown that the situation is essentially associated with enlargement of the compressive thrust force and its
approaching to the Eulerian critical value. Then, the bending stiffness of the drill string reduces, it hogs and
the diamond impregnations existing in the bit surface penetrate into the rock medium. As this takes place, the
bit axis tilts and nutates. It should be particularly emphasized that at this stage, the bit is under action of the
vertical force (weight on bit) which essentially exceeds all other forces. It presses the bit to the hole bottom (not
to the hole wall) and the bit loses its ability to slide on the bore-hole bottom and begins to roll on its surface,
lagging behind or outstripping the drill string rotation. As a result, the point of the bit contact with the reference
surface (the instantaneous centre of velocities) may describe extremely complicated trajectories with
loops and cuspidal points and to change the motion directions. As examples, whirling of spherical bit is considered.
Опис
Ключові слова
deep drilling, drill bits, nonholonomic dynamics, forward and backward whirls
Бібліографічний опис
Gulyayev V. I. Incipient Regimes of Drill Bit Whirlings on Uneven Bottoms of Deep Bore-Holes / V. I. Gulyayev, O. V. Vashchilina, S. M. Glazunov // Nonlinear Dynamics–2016 (ND-KhPI2016) : proceedings of 5th International Conference, dedicated to the 90th anniversary of Academician V. L. Rvachev, September 27-30, 2016 = Нелінійна динаміка–2016 : тези доп. 5-ї Міжнар. конф., 27-30 вересня 2016 р. – Kharkov : NTU "KhPI", 2016. – P. 312-317.