Borehole Cutting Assembly Torque Control
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Solution Overview
Problem
Conventional borehole cutting technologies face challenges in rotating the drill pipe while steering, leading to sticking and slipping issues, especially when attempting to cut highly deviated holes, as existing controlled torque couplings are limited in scalability and effectiveness, particularly with larger motor sizes.
Innovation Solution
A borehole cutting assembly utilizing a progressive cavity pump as a controlled torque coupling, which includes a rotor and stator with fluid flow cavities to counteract tool reaction torque, allowing for adjustable fluid flow control to steer the cutting head and enable rotation of the drill pipe, thereby overcoming the limitations of previous technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bent housing is used below the PDM to guide the cutting tool at an angle, then directional cutting capability is improved, but the drill pipe cannot be rotated leading to sticking and slipping issues
Solution Approach 1:
The system is divided into two independent rotational segments: the drill pipe can rotate independently at surface, and the cutting head can rotate independently downhole. The flexible shaft connects these segments, allowing each to rotate without forcing the other, thus enabling both directional cutting and drill pipe rotation simultaneously
Solution Approach 2:
A flexible shaft is used to connect the drill pipe to the cutting head, allowing relative rotation between the two components. This flexible connection transmits torque while accommodating angular misalignment and independent rotation, resolving the contradiction between maintaining directional orientation and allowing drill pipe rotation
2Reliability
If the drill pipe is continuously rotated to sweep out a hole with no preferred direction, then sticking and slipping are prevented, but the ability to cut highly deviated holes is limited
Solution Approach 1:
By segmenting the rotational capability between drill pipe and cutting head, the system can maintain drill pipe rotation for reliability while the cutting head maintains a fixed orientation for cutting deviated holes, eliminating the need to choose between the two objectives
Solution Approach 2:
The system dynamically separates the rotation functions: the drill pipe rotates continuously to prevent sticking, while the cutting head maintains a fixed angular orientation to cut deviated holes. The flexible shaft allows this dynamic separation of rotational movements
3Adaptability or versatility
If existing controlled torque couplings are used, then some torque control is achieved, but scalability to larger motor sizes is limited
Solution Approach 1:
The progressive cavity pump is designed to function both as a fluid injection device and as a controlled torque coupling mechanism. By controlling the fluid flow to the pump, torque can be controlled to accommodate various motor sizes from 3 inches to 10 inches and beyond, providing universal scalability
Solution Approach 2:
The controlled torque coupling effectiveness is adjusted by changing the fluid flow parameters to the progressive cavity pump. By varying the fluid flow rate and pressure, the torque transmission can be controlled to match the requirements of different motor sizes, enabling scalability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient directional cutting and rotation of the drill pipe during steerable drilling, allowing for larger and smaller motor sizes, improving the ability to cut deviated holes without sticking, by effectively managing tool reaction torque through fluid flow control.
Implementation Method 1
a controlled torque coupling comprising a progressive cavity pump having a rotor and a stator each provided with drive formations arranged to define a fluid flow cavity therebetween, rotation of the rotor relative to the stator forcing fluid flow through the cavity to counteract the tool reaction torque
Data Source
AI summary
A borehole cutting assembly for directional cutting in a borehole, the assembly comprising an input pipe and a cutting head rotatably mounted on the input pipe such that the orientation of the cutting head relative to the input pipe can be altered to determine the direction of cutting of the borehole. A cutting tool and cutting tool motor are mounted on the cutting head to enable the cutting tool to be rotatably driven relative to the cutting head so that when the cutting tool is loaded in use the cutting head is subject to a tool reaction torque that acts to rotate the cutting head to change the orientation of the cutting head. The cutting head is rotatably mounted on the input pipe by a controlled torque coupling comprising a progressive cavity pump having a rotor and a stator each provided with drive formations arranged to define a fluid flow cavity therebetween. Rotation of the rotor relative to the stator forces fluid flow through the cavity to counteract the tool reaction torque. Fluid flow control means is provided to resist the flow of fluid through the cavity in use and thus to control the magnitude of the counteraction generated by the progressive cavity pump to the tool reaction torque.