Short-Radius Drilling Tool With Articulated Flexible String
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Solution Overview
Problem
Existing rotary steering systems are inherently rigid and unable to adapt to the needs of short-radius drilling, limiting their whipstocking capacity and ability to navigate curved boreholes, resulting in inefficient and costly drilling operations.
Innovation Solution
A short-radius trajectory-controllable drilling tool featuring a controllable flexible weight on bit (WOB) & torque transmission drilling string with deflectable load-bearing joints, an electrical actuator, and a steering actuator, allowing for large deflections and precise control of borehole trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional rotary steering system is used, then the system structure is simple and rigid, but it cannot achieve short-radius directional drilling with curvature radius less than 15°/30m
Solution Approach 1:
The drilling string is segmented into multiple articulated sections with universal joints, allowing each segment to deflect independently. This segmentation enables the drilling string to navigate sharp curves with radius as small as 3-10 meters while maintaining structural integrity and torque transmission capability.
Solution Approach 2:
The system transitions from a rigid static structure to a dynamic articulated structure. The universal joints and deflectable components allow real-time adjustment of the drilling string configuration, enabling adaptation to varying borehole curvatures and directional drilling requirements.
2Adaptability or versatility
If the drilling string is made flexible to achieve short-radius deflection, then the adaptability improves, but the torque transmission capability and structural stability deteriorate
Solution Approach 1:
The articulated sections combine flexible universal joints with high-strength torque transmission components. The composite structure of the deflectable drilling string integrates elements that provide both flexibility for deflection and sufficient strength for torque transmission in short-radius applications.
Solution Approach 2:
The universal joints employ spherical geometry to accommodate multi-directional deflections while maintaining continuous torque transmission. The curved articulation points allow the drilling string to bend sharply without compromising the mechanical connection or torque transfer efficiency.
3Strength
If a rigid drilling string is used, then the torque transmission is efficient, but it cannot pass through curved boreholes with small radius
Solution Approach 1:
The drilling string is divided into multiple articulated segments connected by universal joints, enabling each segment to independently deflect and navigate curved boreholes while maintaining continuous torque transmission through the articulated chain.
Solution Approach 2:
The deflectable drilling string employs flexible articulated components that can bend and conform to curved borehole paths. These flexible elements maintain sufficient structural integrity to transmit torque while adapting to the geometric constraints of short-radius directional drilling.
Data Source
AI summary
A short-radius trajectory-controllable drilling tool and a combined type steerable drilling tool, including a drill bit and a controllable flexible WOB and torque transmission drilling string. The controllable flexible WOB and torque transmission drilling string includes a deflecting lever and a plurality of load-bearing joints. A lower end of the deflecting lever is fixedly connected to the drill bit. Every two adjacent load-bearing joints are hinged by means of a deflectable WOB and torque transmission assembly. The lowermost load-bearing joint is a load-bearing body, and a steering actuator is disposed on the load-bearing body. A lower portion of the deflecting lever is hinged to a lower portion of the loading-bearing body by means of a controllable WOB and torque deflection transmission assembly.