Hydraulic Wireline Tool Speed Control Under Pulling Force Limits
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Solution Overview
Problem
Hydraulically driven downhole self-propelling wireline tools face limitations in speed without compromising maximum pulling force, while electrically driven tools lack sufficient pulling force for inaccessible well parts, leading to inefficiencies in well intervention operations.
Innovation Solution
A method controlling a tool string with a downhole self-propelling wireline tool that adjusts the operational rotational speed of the electric motor based on maximum allowable electric power usage, ensuring the tool operates within power limits, allowing for continuous speed adjustment without exceeding current limits, thus maintaining maximum pulling force and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydraulic power is increased to drive wheels faster, then speed is improved, but maximum pulling force is reduced
Solution Approach 1:
The hydraulic system implements dynamic control where the rotational speed of the electric motor driving the hydraulic pump is continuously adjusted based on real-time feedback from sensors measuring tool speed and pulling force. This allows the system to adaptively optimize the balance between speed and pulling force, transitioning smoothly between operational modes rather than being restricted to fixed two-speed operation.
Solution Approach 2:
The system changes operational parameters by adjusting the rotational speed of the electric motor and the flow rate of hydraulic fluid to the wheels. By dynamically modifying these parameters based on sensor feedback, the system can operate at high speed when pulling force requirements are low, and switch to high torque mode when maximum pulling force is needed, thereby resolving the contradiction between speed and force.
2Speed
If electric motor rotational speed is increased to drive the tool faster, then speed is improved, but electric power consumption exceeds maximum allowable limits
Solution Approach 1:
The system incorporates feedback control where sensors continuously monitor the rotational speed of the electric motor and the current drawn from the power supply. This information is fed back to the control system, which adjusts the motor speed to maintain it below the maximum allowable operational rotational speed at the determined torque, ensuring power consumption remains within limits while optimizing tool speed.
Solution Approach 2:
The control system dynamically adjusts the electric motor's rotational speed based on real-time conditions, including the determined motor output torque and maximum allowable power usage. This dynamic adjustment allows the system to operate at near-maximum speed when power availability permits, while automatically reducing speed when approaching power limits, thereby resolving the contradiction between speed and power consumption.
3Force
If hydraulic fluid pressure is increased to press wheels outward for more pulling force, then pulling force is improved, but speed is reduced to very low speed
Solution Approach 1:
The system changes hydraulic parameters by adjusting both the pressure and flow rate of hydraulic fluid to the wheels. By dynamically modifying these parameters based on sensor feedback, the system can operate at high speed when pulling force requirements are low, and switch to high torque mode when maximum pulling force is needed, thereby resolving the contradiction between speed and force.
4Force
If electric motor torque is increased to provide more pulling force, then pulling force is improved, but rotational speed must be reduced
Solution Approach 1:
The control system dynamically adjusts the electric motor's operational parameters, specifically the relationship between torque and rotational speed. By continuously monitoring the determined motor output torque and comparing it with the maximum allowable operational rotational speed at that torque, the system optimizes the torque-speed balance to maximize pulling force while maintaining the highest possible speed within power constraints.
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 the hydraulically driven tool to drive faster without reducing pulling force and ensures the electrically driven tool can provide sufficient pulling force, optimizing power usage and preventing component overload, thereby enhancing well intervention efficiency.
Implementation Method 1
an electric motor rotating at an operational rotational speed for driving the first pump
Implementation Method 2
a first hydraulic pump driven by the electric motor for generation of a second fluid pressure of a second fluid for driving the hydraulic motors
Implementation Method 3
each wheel comprising a hydraulic motor for rotation of the wheel to provide a self-propelling movement
Implementation Method 4
each wheel being connected to a projectable arm assembly projectable from the tool body by means of hydraulic fluid from the first hydraulic pump
Data Source
AI summary
The present invention relates to a method for controlling a tool string having a downhole self-propelling wireline tool having wheels rotated by means of hydraulics and connected to projectable arm assemblies projected by hydraulics, comprising running a downhole self-propelling wireline tool into a wellbore, the downhole self-propelling wireline tool being connected to a second end of a wireline, and a first end of the wireline being connected to a power supply, the downhole self-propelling wireline tool having a tool body and a plurality of wheels rotated by means of hydraulics, and each wheel being connected to a projectable arm assembly projectable from the tool body by means of hydraulic fluid from a first hydraulic pump, the downhole self-propelling wireline tool having an electric motor rotating at an operational rotational speed for driving the first pump; supplying electric power to the downhole self-propelling wireline tool to operate the downhole self-propelling wireline tool at a first speed to urge the downhole self-propelling wireline tool through the wellbore at a first force; determining a motor output torque of the electric motor; determining a maximum allowable motor rotational speed based on the motor output torque; and comparing the operational rotational speed with the maximum allowable motor rotational speed, wherein the method further comprises adjusting the operational rotational speed of the electric motor based on the comparison in order to adjust the first speed to a second speed if the operational rotational speed is higher than the maximum allowable motor rotational speed. The invention also relates to a hydraulically driven downhole self-propelling wireline tool configured to perform the method.