Study of the screw downhole steering engine performance in the mode of drill string rotation

UDK: 622.243.2

Key words: bottom-hole assembly, screw steerable motor, curved sub; centralizer

Authors: E.G. Grechin (Tyumen Industrial University, RF, Tyumen), S.N. Bastrikov (Siberian Scientific and Research Institute for Oil Industry JSC, RF, Tyumen)

The subject of the study is a performance of the assembly with the controlled downhole steering engine used at drilling wells completed by directional and horizontal holes. The technology applied provides for alteration of modes of drill string rotation and sliding (directional drilling). It is pointed out that to improve the quality of the borehole and the drilling performance it is necessary to increase the extent of the area of drilling in the mode of the drill string rotation which will require determining the influence of various factors upon the well path in the given mode. As a result of the theoretical study a number of regularities have been identified. When the steering engine turns within the set angle of 270-90^o the assembly operates for reducing the inclination angle, the response on the drill bit does not depend on the hole diameter and very little on the drift angle of the screw downhole steering engine (SDSE) and increases approximately by 1.5 times with the inclination angle increase from 30 to 90^o. Within the steering engine set angle of 90-0^o, 0-270^o the assembly operates for the increase of the inclination angle, the response on the drill bit depends on the hole diameter and on the drift angle of SDSE and very little on the inclination angle. The increase of the inclination angle creates the tendency towards its drop in the mode of rotation; the increase of the angle of the SDSE skewing promotes the inclination angle growing. At drilling in soft rocks a tendency to the inclination angle drop will prevail, and at drilling in hard rocks the inclination angle growing will occur. The regularities identified will permit an operator to define the path correction parameters more precisely taking into account the specific conditions, to increase the extent of the drilling area in the mode of the drill string rotation reducing by this a number of shifts to directional drilling.
References
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gorizontal'nykh i mnogozaboynykh skvazhin (Drilling of inclined, horizontal
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NefteGaz Publ., 2011, 647 p.
2. Grechin E.G., Pashkov E.V., The study of stresses and deformations occurring
during work of a drill-pipe string assembly with bottom-hole screw steerable
motor (In Russ.), Stroitel'stvo neftyanykh i gazovykh skvazhin na sushe i na
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