Downhole Gas Control Valves for Well Unloading
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Solution Overview
Problem
Conventional continuous gas lift systems for oil and gas wells face challenges such as complex design requirements, precise tuning for each well, and increased stress on components like bellows at greater depths, leading to inefficiencies and potential failures, especially in deeper wells.
Innovation Solution
The development of downhole gas control valves using a stack of Belleville washers and a piston assembly, actuated by fluid pressure, which allows for precise control of gas flow through a common control line, simplifying the system and reducing the need for individual tuning at each depth, and utilizing pocket mandrels for easy installation and replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional continuous gas lift systems are used in deeper wells, then gas injection control is needed, but component stress increases and reliability decreases
Solution Approach 1:
The gas lift system is segmented into multiple injection valves positioned at different depths in the wellbore. Each valve independently controls gas injection at its specific location, distributing the control function across multiple components rather than relying on a single high-stress valve. This segmentation reduces the stress burden on individual components while maintaining reliable gas injection control throughout the well.
2Ease of operation
If conventional gas lift valves are used, then gas flow control is achieved, but system complexity and tuning requirements increase
Solution Approach 1:
The gas injection valves are designed with universal functionality to perform multiple operations: controlling gas injection, regulating flow rates, and adapting to varying well conditions. Each valve can operate independently or in coordination with others, providing versatile control capabilities that reduce the need for complex system-wide tuning while maintaining ease of operation across different well depths and production scenarios.
3Productivity
If gas injection is increased to maintain production, then liquid production is improved, but component stress and failure risk increase
Solution Approach 1:
The gas injection function is divided among multiple valves positioned at different depths, allowing production enhancement to be distributed across several components rather than concentrated in one. This segmentation enables the system to maintain or increase liquid production rates while preventing excessive stress on any single component, thereby preserving overall system reliability even as productivity increases.
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 solution enhances the reliability and efficiency of gas lift operations by allowing precise control of gas injection valves independent of casing pressure, reducing the complexity of system design, and extending the lifespan of components, while enabling flexible operation across varying well depths.
Implementation Method 1
The stack of Belleville washers is under compression to bias the piston in the normal position and resist movement of the piston away from the normal position
Implementation Method 2
The piston is responsive to fluid pressure in the actuating chamber and the washer stack such that the valve body may be selectively seated on the valve seat by sequentially increasing and decreasing pressure in the actuating chamber relative to the biasing force of the washer stack
Data Source
AI summary
A method of unloading and producing liquids from a well uses a plurality of gas injection valves installed on a production tubing. The injection valves are controlled by pressure signals transmitted through a single fluid control line. A first pressure signal is applied to the control line to open the plurality of injection valves. Gas is pumped into the annulus at an injection pressure until a first pressure drop occurs in the injection pressure, the first pressure drop being indicative of gas flowing through a first, upper one of the injection valves. Pumping of gas is continued until a second pressure drop occurs in the injection pressure, the second pressure drop being indicative of gas flowing through a second, lower one of the injection valves. A second, lower pressure signal then is applied to close the first injection valve while leaving the second injection valve open.