Non-rotating Drill String with Surface Motor for Reaming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drilling methods for reaming pilot holes in rock formations are limited by material fatigue and short lifetime due to torsional forces in long drill strings, leading to restricted hole length and increased vibrations, making them costly and inefficient.
Innovation Solution
A drilling device with an electrically driven drill bit, where rotation is provided by electromotors through a gear system, and a non-rotating drill string is used, with axial displacement and hydraulic support to manage torque and friction, allowing for efficient reaming without a rotating drill string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a rotating drill string is used to ream a pilot hole, then the drill string can rotate the drill bit, but material fatigue and short lifetime occur due to great torsional forces
Solution Approach 1:
The rotational function is extracted from the drill string and transferred to a separate rotation device positioned on the surface. The drill string itself becomes non-rotating, carrying only axial thrust, which eliminates torsional forces and material fatigue in the drill string, thereby extending its lifetime while maintaining drill bit rotation capability.
Solution Approach 2:
A separate rotation device acts as an intermediary between the surface and the drill bit. This intermediary component performs the rotation function externally, allowing the drill string to remain stationary in terms of rotation while still transmitting axial force, thus resolving the conflict between needing rotation and avoiding torsional stress.
2Length of moving object
If a long drill string is used to reach greater hole lengths, then the achievable hole length increases, but torsion becomes too great causing large vibrations and reduced lifetime
Solution Approach 1:
The rotational function is extracted from the drill string system and placed on the surface. This allows the drill string to be purely axial without torsional components, enabling longer drill strings to be used without the vibration and stability problems caused by torsion in traditional rotating drill strings.
3Power
If a rotating drill string is used, then the drill bit can be rotated, but great torsional forces result in reduced lifetime
Solution Approach 1:
The rotational function is extracted from the drill string and performed by a separate surface-based rotation device. The drill string becomes a non-rotating axial thrust carrier, eliminating torsional forces that cause material fatigue and extending its operational lifetime, while the drill bit still receives rotation from the external device.
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
This approach significantly reduces material fatigue, extends drill string lifetime, and enables longer hole lengths with reduced vibrations and stress, providing a cost-effective and environmentally friendly solution for infrastructure development in rock formations.
Implementation Method 1
roller cutters, which are arranged to break up the rock formation
Implementation Method 2
roller cutters, which are arranged to break up the rock formation
Implementation Method 3
hydraulic cylinders arranged to press supporting feet against a surrounding borehole wall
Implementation Method 4
supporting feet that are pressed against a surrounding borehole wall by means of hydraulic cylinders
Implementation Method 5
rotation of the drill bit is provided by electromotors
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
A drilling equipment device (2') for use when reaming a pilot hole (13) in a rock formation (1), in which a drilling unit (2) comprises a rotatable drill-bit structure (15) fitted with roller cutters (12) which are arranged to break up the rock formation (1), the drill-bit structure (15) and an associated housing (16) being supported on a drill stem (21) which is connected in a rotationally rigid manner to a non-rotatable drill string (4). A method of reaming a pilot hole (13) in a rock formation (1) is described as well.