Automatic Choke System for Precise Casing Pressure Control
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Solution Overview
Problem
Conventional back pressure control devices in drilling operations require manual adjustments to maintain optimal operating pressures, which can be unstable due to variations in drilling fluid characteristics, such as density and temperature, leading to difficulties in controlling pressures within a narrow acceptable range.
Innovation Solution
An automatic choke system with a PID controller that senses actual pressures and generates a set point pressure signal to adjust the choke operation, using a proportional-integral-differential (PID) controller to maintain precise control of casing pressure, drill pipe pressure, and bottom hole pressure within a narrower window of ±5 psi.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual control of choke orifice is used, then device complexity is reduced, but pressure control precision deteriorates (cannot maintain narrow ±5 psi window)
Solution Approach 1:
The patent implements a closed-loop feedback control system where a pressure sensor continuously monitors the actual pressure in the wellbore, compares it with the target pressure, and automatically adjusts the choke orifice position to maintain pressure within the narrow ±5 psi window. This feedback mechanism resolves the contradiction by achieving high precision control without requiring complex manual intervention.
Solution Approach 2:
The control system is designed to be self-regulating, automatically adjusting the choke opening based on real-time pressure measurements without requiring continuous manual intervention. The system monitors its own performance and makes corrective adjustments autonomously, maintaining precise pressure control while simplifying operator workload.
2Reliability
If conventional manual control is used, then ease of operation is improved, but reliability deteriorates (unstable control due to fluid variations)
Solution Approach 1:
The system continuously monitors pressure and automatically adjusts the choke response to fluid density and temperature variations, eliminating the instability inherent in manual control. The feedback loop ensures reliable maintenance of pressure within acceptable ranges regardless of drilling fluid characteristic changes.
Solution Approach 2:
The patent replaces manual mechanical adjustment with an automated electromechanical or electronic control system. The choke actuator is controlled by an electric motor or pneumatic system responsive to electronic signals from the pressure sensor, eliminating human reaction time delays and improving control reliability.
3Productivity
If automatic choke control is implemented, then productivity is improved (narrower pressure control window), but device complexity increases
Solution Approach 1:
The control system integrates multiple functions into a single unified device: pressure sensing, signal processing, choke actuation, and safety monitoring. This multi-functionality achieves improved drilling productivity through precise pressure control while minimizing the addition of separate complex subsystems.
Solution Approach 2:
The patent introduces a programmable logic controller (PLC) or microprocessor-based control unit as an intermediary between the pressure sensor and choke actuator. This intelligent intermediary processes sensor signals, executes control algorithms, and drives the choke mechanism, achieving high productivity through automated control while managing system complexity through modular design.
Data Source
AI summary
Back pressure control devices used to control fluid pressure in a wellbore require various utilities for operation, such as an air supply. Apparatus disclosed herein provide for the continued operation of one or more back pressure control devices when supply of utilities for operation of the back pressure control devices are intentionally or unintentionally interrupted.