Closed-loop hydraulic drilling choke calibration
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Solution Overview
Problem
Conventional closed-loop drilling systems lack precision in managing wellbore pressure and condition monitoring, leading to increased costs and safety risks due to unreliable choke valve performance and reliance on trial-and-error methods.
Innovation Solution
An improved closed-loop drilling system that generates choke characteristic curves through calibration, allowing for precise control of wellbore pressure by correlating commanded choke valve position with pressure drop and fluid density, enabling condition monitoring and reducing the need for expensive flow meters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional closed-loop drilling systems are used, then basic wellbore pressure control is achieved, but precision in pressure management and condition monitoring deteriorates
Solution Approach 1:
The system performs preliminary calibration by injecting known volumes of calibration fluid through the calibration fluid injector before actual drilling operations. This establishes baseline choke characteristic curves that correlate commanded choke valve positions with actual pressure drops and flow rates, enabling precise pressure management from the start of operations without relying on trial-and-error methods
Solution Approach 2:
The system continuously monitors actual wellbore pressure, choke valve position, and flow rate data, then feeds this information back to the control system. The control system compares actual pressure management outcomes with predicted values based on calibrated choke characteristic curves, and automatically adjusts choke valve commands to achieve target pressure profiles, significantly improving both precision and reliability
2Ease of operation
If trial-and-error methods are used for choke valve calibration, then system setup is simplified, but operational time and safety risks increase
Solution Approach 1:
The system performs preliminary calibration by injecting known volumes of calibration fluid through the calibration fluid injector before actual drilling operations. This establishes baseline choke characteristic curves that correlate commanded choke valve positions with actual pressure drops and flow rates, enabling precise pressure management from the start of operations without relying on trial-and-error methods
Solution Approach 2:
The system replaces manual trial-and-error calibration procedures with an automated calibration fluid injection system. The calibration fluid injector, volumetric flow rate sensor, and control system work together to automatically determine choke characteristic curves, eliminating the need for operators to manually adjust choke valves through repeated testing and significantly reducing calibration time
3Measurement precision
If expensive flow meters are used, then flow rate measurement precision improves, but system cost increases
Solution Approach 1:
The system introduces calibration fluid as an intermediary substance to indirectly measure flow rate characteristics. By injecting known volumes of calibration fluid and measuring the resulting pressure drops across the choke valve, the system derives flow rate information without requiring expensive flow meters. The calibration fluid acts as a mediator that translates choke valve position commands into measurable pressure signals that reveal flow characteristics
Solution Approach 2:
The system creates a simplified model of flow measurement by using calibration fluid injection to replicate the information that expensive flow meters would provide. The choke characteristic curves, established through calibration fluid testing, serve as a copied or alternative representation of flow rate data, enabling precise flow monitoring through pressure measurements alone
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
This system provides accurate and reliable wellbore pressure management, enhances safety, and reduces operational costs by enabling predictive maintenance and adoption in low-specification applications without requiring a flow meter.
Implementation Method 1
The pressure tight seal on the annulus allows for control of wellbore pressure by manipulation of the choke valve position, which is directly related to the choke aperture, of the choke valve and the corresponding application of surface backpressure
Implementation Method 2
The data acquisition and control system generates a choke performance curve, choke characteristic curve, or data thereof by closing the wellbore isolation valve, engaging the secondary fluid pumping system, varying a commanded choke setting of the choke manifold through a plurality of set points, and recording a pressure drop across the choke valve at each of the set points
Data Source
AI summary
A closed-loop hydraulic drilling system generates choke characteristic curves or data that more accurately reflects the relationship between the commanded choke valve position and the resulting pressure drop across the choke valve for a given flow rate and fluid density. The choke characteristic curves may be generated through a calibration procedure and then used during normal operations to more accurately monitor return flow and manage wellbore pressure. The specific gravity of an injected calibration fluid and pressure drop across the choke valve may be determined and correlated to the current choke valve position to reflect the choke characteristic curve in situ, thereby providing for more precise control of wellbore pressure and enabling condition monitoring of the choke valve. In addition, an improved closed-loop hydraulic drilling system does not require a flow meter, enabling the adoption of MPD systems in low-specification and economically constrained applications.