Wellbore Pressure Control via Hydraulic Model Prediction
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Solution Overview
Problem
Existing Managed Pressure Drilling (MPD) systems face issues with robustness against disturbances and performance degradation during critical operations, particularly due to high controller gain requirements and the need for continuous tuning of parameters as the well length increases, leading to instability and chattering issues.
Innovation Solution
A method that calculates a desired extraction flow rate from the wellbore annulus using a determined pressure offset, scaling it by volume and bulk modulus, and setting flow control devices to achieve this rate, reducing the need for retuning and enhancing robustness against disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high controller gain is used to achieve fast response to pressure variations, then response speed is improved, but robustness against disturbances deteriorates
Solution Approach 1:
The control system performs preliminary actions by predicting future pressure deviations using a hydraulic model before they actually occur. The model anticipates pressure changes based on current system state and control inputs, allowing the controller to prepare appropriate corrective actions in advance, thus achieving fast response without requiring high gain that would compromise stability.
Solution Approach 2:
The system implements feedback by continuously comparing actual pressure measurements with predicted pressure values from the hydraulic model. This feedback mechanism allows the controller to detect deviations and adjust control inputs accordingly, maintaining robustness while achieving responsive control through model-based prediction rather than high gain.
2Ease of operation
If conventional feedback control is used to maintain pressure stability, then ease of operation is improved, but performance during critical operations deteriorates
Solution Approach 1:
The hydraulic model performs preliminary calculations to predict pressure behavior during critical operations such as pump ramp-up/down and drill string movements. By anticipating pressure deviations before they occur, the system can prepare appropriate control actions, maintaining performance during critical operations while keeping the control system relatively simple to operate.
3Reliability
If controller parameters are continuously tuned to maintain performance as well length increases, then performance is improved, but loss of time increases
Solution Approach 1:
The hydraulic model is designed to dynamically adapt to changing well conditions, particularly increasing well length. The model automatically adjusts its predictions based on current system parameters such as annulus volume, fluid compressibility, and well geometry, eliminating the need for manual parameter tuning while maintaining accurate performance throughout the drilling operation.
Solution Approach 2:
The control system performs self-service by automatically adapting to changing well conditions through the hydraulic model. The model continuously updates its predictions based on current system state and operational parameters, allowing the system to maintain optimal performance without external intervention for parameter tuning, thus saving time and improving efficiency.
4Device complexity
If simple empirical models are used for MPC, then device complexity is reduced, but manufacturing precision deteriorates due to need for continuous updating
Solution Approach 1:
The hydraulic model is designed to dynamically adapt to changing well conditions without requiring continuous manual updating. The model automatically adjusts its predictions based on current system parameters such as annulus volume, fluid compressibility, and well geometry, maintaining control precision while keeping the system relatively simple.
Solution Approach 2:
The model performs self-service by automatically updating its predictions based on real-time system state and operational parameters. This self-updating capability maintains control precision without requiring continuous manual tuning or complex calibration procedures, achieving a balance between simplicity and accuracy.
Data Source
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AI summary
A method of controlling the annular pressure in a well during a well construction operation. The operation comprises pumping a fluid down a tubing located within the well and extracting the fluid that flows back through an annulus within said well and surrounding the tubing. The method comprises defining a set pressure pref, determining a desired extraction flow rate qc of fluid from said annulus in dependence upon the set pressure pref and a pumped flow rate into the annulus, and configuring an extraction path to achieve said desired extraction flow rate.