Blade-Integrated Downhole Rotary Drive for Casing Torque Limits
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Solution Overview
Problem
Conventional downhole rotary drive systems for drilling or reaming boreholes face limitations such as torque constraints in casing connections, complex and costly drilling assemblies, and inefficiencies in drilling deep or deviated wells.
Innovation Solution
A downhole rotary drive apparatus featuring a body with radially-projecting blade portions, an output shaft for coupling to a bit, and a transmission arrangement with rotary drives and drive components, where the rotary drives and transmission arrangement are located within the blade portions to enhance power generation and protection from damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If casing drilling is used to rotate the drill bit from surface, then drilling can be performed with the bore-lining tubing string, but the torque limits of the casing connections are reached before the desired depth is reached
Solution Approach 1:
The patent replaces the mechanical torque transmission system (casing connections) with a downhole motor system that converts hydraulic energy to mechanical rotation. The motor assembly with rotors and stators eliminates the torque limitation of casing connections by generating rotation directly at the drill bit location through fluid-powered mechanical conversion.
Solution Approach 2:
The patent employs hydraulic power transmission through drilling fluid to drive the downhole motor. The motor assembly utilizes the hydraulic energy of circulating drilling fluid to rotate the drill bit, replacing mechanical torque transmission through casing with hydraulic-powered rotation at depth.
2Force
If complex drilling assemblies are used to deliver power to the drill bit downhole, then torque limitations are overcome, but the assemblies are expensive and unreliable
Solution Approach 1:
The patent extracts the power delivery function from complex assembled drilling equipment and integrates it directly into the drill string itself. The motor assembly is incorporated within the tubular string structure, eliminating the need for separate, complex power delivery assemblies and their associated reliability issues.
Solution Approach 2:
The tubular string serves multiple functions: it provides structural support, acts as the conduit for hydraulic power transmission, and houses the motor assembly. This multi-functional design eliminates the need for separate complex assemblies, reducing cost and improving reliability through integration.
3Force
If complex drilling assemblies are used to deliver power to the drill bit downhole, then torque limitations are overcome, but the assemblies are recovered to surface once the well is drilled which is time consuming
Solution Approach 1:
The patent merges the motor assembly with the drill string/tubular string into a single integrated unit. This combination allows the power delivery system to be run into and recovered with the drill string itself, eliminating separate recovery operations and reducing time loss.
4Productivity
If the rotary drives and transmission arrangement are positioned to maximize power transmission, then drilling efficiency is improved, but the components become vulnerable to damage from drill cuttings and abrasive particulate matter
Solution Approach 1:
The patent nests the motor assembly and transmission components within the hollow interior of the tubular string. This nesting provides inherent protection from external contaminants while maintaining the mechanical functions needed for power transmission to the drill bit.
Solution Approach 2:
The tubular string acts as a protective shell enclosing the motor assembly. This shell barrier shields the sensitive rotational components from drill cuttings and abrasive particulate matter in the annulus, preventing damage while allowing the system to operate in harsh downhole environments.
Data Source
AI summary
A downhole rotary drive apparatus (10) for driving a bit (12) used to drill or ream a borehole (B) comprises a body (14) configured for coupling to, or forming part of, a tubular string (S1;S2;S3) for running into the borehole (B) and an output shaft (16) at least partially disposed within and rotatably mounted to the body (14). A plurality of rotary drives (32) are disposed around the body (14), each having a rotor (36). The apparatus (10) further comprises a transmission arrangement (46) comprising a drive component mounted on at least one of the rotors (36) of the rotary drives (32) and a driven component mounted on the output shaft (16). The driven component is disposed radially inwards of the drive component such that an inner surface of the drive component engages an outer surface of the driven component, rotation of the driven component by the drive component driving rotation of the output shaft (16). The rotary drives (32) and/or the transmission arrangement (46) of the rotary drive apparatus (10) are disposed within blade portions disposed on or formed in the body (14).