Linear Motor Choke Biasing for Borehole Pressure Control
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Solution Overview
Problem
Existing systems for controlling operating pressures in subterranean boreholes, such as those in oil and gas wells, face challenges with manual control precision and reliability, leading to potential underground blowouts and inefficiencies during low-pressure operations due to mechanical 'sticktion' issues.
Innovation Solution
A choke system utilizing a linear motor to generate hydraulic forces and apply bias forces, allowing for precise control of fluid flow and reducing the overpressure required to initiate movement, thereby maintaining set point pressures within the borehole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual control of choke is used to maintain operating pressures, then operator can adjust pressures, but control precision is poor and reliability is low leading to potential blowouts
Solution Approach 1:
The patent replaces manual mechanical choke control with an automated electro-hydraulic system. A linear motor generates electrical signals that are converted to hydraulic force through a hydraulic cylinder, which actuates the choke valve. This substitution eliminates manual operation errors and provides precise, reliable pressure control through automated feedback mechanisms.
Solution Approach 2:
The system incorporates pressure sensors that continuously monitor operating pressures and feed this information back to the control system. The controller compares actual pressures with target pressures and automatically adjusts the linear motor output to maintain precise pressure control, thereby improving both reliability and precision simultaneously.
2Reliability
If high closing force is applied to move choke member to closed position, then pressure control is improved, but overpressure is required to initiate movement due to mechanical sticktion
Solution Approach 1:
The patent applies a preliminary bias force to the choke member using a spring mechanism before the closing operation begins. This pre-applied force reduces the static friction and mechanical sticktion, allowing the choke member to initiate movement with lower overpressure. The bias force is then released or reduced once movement begins, enabling smoother operation and reducing peak pressure requirements.
3Measurement precision
If electrical energy is converted to hydraulic force using linear motor, then precise pressure control is achieved, but system complexity increases
Solution Approach 1:
The patent merges the linear motor and hydraulic cylinder into an integrated electro-hydraulic actuator assembly. The linear motor is directly coupled to the hydraulic piston, combining electrical actuation and hydraulic force multiplication in a single compact unit. This integration reduces the number of separate components, simplifies the overall system architecture, and maintains precise pressure control capability.
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
The system achieves tighter control of operating pressures, reduces the risk of blowouts, and improves operational efficiency by minimizing the overpressure needed to initiate movement, especially during low-pressure operations, ensuring smoother pressure regulation.
Implementation Method 1
leveraging electrical energy to generate hydraulic force through linear motors or rotary servo motors
Implementation Method 2
leveraging electrical energy to generate hydraulic force through linear motors or rotary servo motors
Data Source
AI summary
A method of controlling one or more operating pressures within a subterranean borehole that includes a choke assembly is disclosed. The choke assembly may include a housing having an inlet passage, an axial bore, and a chamber, wherein a portion of the axial bore forms an outlet passage, and a choke member adapted for movement in the housing to control the flow of a fluid from the inlet passage to the outlet passage. The method may include applying a closing force to move the choke member toward a closed position, and applying a bias force to the choke member when in the closed position to reduce an overpressure required to initiate movement of the choke member from the closed position.