Drilling Start Control in Existing Boreholes Using Friction Torque
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Solution Overview
Problem
Conventional drilling systems are inefficient when starting a drilling operation in an existing borehole due to high wall friction, often causing the drilling device to be driven out of the borehole, leading to unsatisfactory results and potential jamming.
Innovation Solution
A method for improved starting of drilling in existing boreholes involves storing a reference torque value, determining the actual friction torque, and comparing it with the reference value while considering the direction of movement, terminating the first operating state if the actual torque is higher and the direction is negative, and transitioning to a second operating state for normal drilling once the drill bit reaches the substrate, allowing for controlled closed-loop torque management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the control device operates with a setpoint/actual-value comparison using reference torque, then the power tool can be controlled during normal drilling on a surface, but the drilling device is driven out of the borehole when starting drilling in an existing borehole due to high wall friction
Solution Approach 1:
The control device dynamically adapts the reference torque based on the detected operating state. When high friction is detected (drilling in existing borehole), the control device switches to a dynamic reference torque that is higher than the static reference torque used for surface drilling. This allows the system to maintain reliable drilling progress in existing boreholes while preserving ease of operation through automatic adaptation.
Solution Approach 2:
The control device changes the torque parameter based on the operating condition. By detecting whether the drill bit is drilling into a surface or into an existing borehole (using direction of movement and friction indicators), the system adjusts the reference torque parameter accordingly. This parameter change resolves the contradiction by providing high enough torque for existing borehole drilling while maintaining optimal control for surface drilling.
2Productivity
If the reference torque is set for normal starting of drilling on a surface, then good working results are achieved on surfaces, but the reference torque is lower than the friction torque during drilling in an existing borehole
Solution Approach 1:
The system uses dynamic reference torque that adapts to the operating state. When the control device detects drilling in an existing borehole (through direction of movement analysis and friction indicators), it switches to a dynamic reference torque that is specifically calibrated to overcome the higher wall friction, thereby providing sufficient force while maintaining surface drilling efficiency through automatic state detection.
Solution Approach 2:
The reference torque parameter is changed based on the detected operating state. The control device monitors drilling conditions and adjusts the reference torque from the lower value optimized for surface drilling to a higher value optimized for existing borehole drilling, resolving the force deficiency while preserving productivity through conditional parameter adaptation.
3Power
If the control device drives the drilling tool out of the borehole to relieve load, then the reference torque can be achieved, but the drilling operation is not advanced and the device is moved out of the borehole
Solution Approach 1:
The control device uses dynamic reference torque that prevents the need to drive the tool out of the borehole. By detecting the high-friction operating state and automatically switching to an elevated reference torque level, the system maintains sufficient power output to overcome wall friction and achieve drilling advancement without triggering the load-relief extraction response.
Solution Approach 2:
The control device uses feedback from direction of movement sensors and friction indicators to detect when drilling in an existing borehole begins. This feedback triggers an automatic increase in reference torque, ensuring that power output remains sufficient to maintain drilling advancement and prevent the harmful feedback loop of extraction due to insufficient torque.
4Loss of energy
If the friction torque is very much lower than the reference torque on account of wall friction during surface drilling, then good working results are achieved, but the same reference torque is insufficient when drilling in an existing borehole where wall friction is higher
Solution Approach 1:
The control device dynamically adjusts the reference torque based on the operating state. During surface drilling, it maintains the lower reference torque that provides good energy efficiency. When drilling in an existing borehole is detected (through direction of movement and friction analysis), it switches to a higher dynamic reference torque that provides sufficient force to overcome the increased wall friction, resolving the force deficiency while preserving energy efficiency through conditional adaptation.
Solution Approach 2:
The reference torque parameter is conditionally changed based on the detected operating state. The system monitors drilling conditions and adjusts the torque parameter from the energy-efficient lower value used for surface drilling to the higher value needed for existing borehole drilling, resolving the force insufficiency while maintaining optimal energy efficiency through parameter adaptation.
Data Source
AI summary
A method for improved starting of drilling with a drilling device in an existing borehole. The drilling device comprises can be operated in a first operating state and in a second operating state, wherein a switchover between the operating states can take place depending on a comparison between friction data and depending on a direction of movement of the drilling device. In a second aspect, the invention relates to a drilling system which comprises a drilling device and an auto-feed device for producing a feed for the drilling device. The drilling system and preferably set up to implement the proposed starting of drilling method. It is furthermore configured in such a way that a switchover between the first operating state and the second operating state occurs as a result of a comparison between an actual value of a friction torque and a reference value in conjunction with determination of a direction of movement of the drilling device.