Advanced directional drilling, especially rotary steerable systems, provides directional control of wellbore while continuously rotating the drill bit. Downhole propulsion/steering mechanism is one of the key components in rotary closed-loop drilling system. Downhole steering/propulsion mechanisms currently used for directional control include adjustable stabilizer, steerable downhole motor and steering actuators used in state-of-the-art rotary steerable systems. The novel electro-mechanical propulsion and steering mechanisms are introduced, in order to produce downhole weight on bit (WOB) and directional control of the drill bit while rotating it as well. The mechanisms are based on high-reduction ratio planetary gear system and DC motor. This propulsion/steering mechanism introduces a unique rotary steering method with a manner of turning screw inside borehole. As a downhole propulsion/steering mechanism, it can be integrated with an existing MWD system to provide directional control and downhole propulsion force on drill bit.
The 13-3/8銆瀋asing of a well was bent down and broken off in the marine development completion process. The cause for the fracture is systematically analyzed by means of chemical composition analysis, mechanical properties testing, macro and micro fracture analysis and metallographic analysis. The results indicate that, the heterogeneity of the casing material and large oxide metallurgical inclusions found in fracture place severely reduce the properties of the material, which lead to the failure of casing pipe in bad service environment.
The reactor is the best structure for the chemical reaction on high pressure. The paper introduces creative design of a type high pressure sealing structure, and validates the feasibility from the mechanical aspect. The stress distribution and deformation are investigated by the finite element analysis method, which provides the design proof for the high pressure sealing structure.
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