Nested Tubing Flow Paths for Gas Well Liquid Unloading
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Solution Overview
Problem
Existing tubing systems for transporting gas-liquid flows in petroleum wells suffer from reduced flow area and efficiency due to the use of smaller diameter tubes, leading to limited liquid production and gas production capacity, exacerbated by the formation of liquid columns and static pressure build-up.
Innovation Solution
A tubing system with a first and second tubing portion, where the second portion is inserted within the first and includes a packer, lateral openings, and a sliding side door to enable multiple flow paths, increasing the wall surface area for liquid transport while maintaining gas flow area, and incorporating features like a retrievable plug and sand control devices to manage flow dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a smaller diameter tube is used to increase gas velocity and shear stress for liquid transport, then liquid unloading capacity is improved, but flow area is reduced leading to limited gas production capacity
Solution Approach 1:
The patent divides the flow conduit into multiple parallel flow paths or channels within the tubing system. This segmentation increases the total wall surface area available for liquid transport while maintaining the overall flow area for gas production, thereby resolving the contradiction between liquid unloading capacity and gas production capacity.
Solution Approach 2:
The patent utilizes the annular space between the velocity string and the production tubing as an additional flow dimension. This annular flow path provides extra wall surface area for liquid transport without reducing the central flow area for gas production, effectively adding another dimension to the flow system.
2Quantity of substance
If the gas phase occupies the main fraction of space for fluid flow, then gas production is maintained, but the quantity of transported liquid is relatively low due to reduced efficiency coefficient
Solution Approach 1:
The patent enables the gas phase to serve dual functions: maintaining gas production while simultaneously transporting liquid. By creating additional wall surface area through segmented flow paths or annular spaces, the system allows the gas phase to efficiently perform both functions without requiring external assistance, thereby improving the quantity of liquid transported while maintaining gas energy efficiency.
3Productivity
If a velocity string is inserted within the production tubing, then liquid unloading capacity is improved, but device complexity increases
Solution Approach 1:
The patent employs a nested structure where the velocity string is inserted within the production tubing, creating a compact integrated system. This nesting approach increases liquid unloading capacity while minimizing the increase in device complexity by utilizing the existing tubing space efficiently.
Solution Approach 2:
The velocity string serves multiple functions: it provides wall surface area for liquid transport, maintains gas flow through its central channel, and can be equipped with additional features like packers and sand control devices. This multi-functionality reduces the need for separate dedicated systems, thereby limiting the increase in device complexity.
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 enhances liquid unloading capacity and flow efficiency by optimizing gas-phase energy distribution and increasing wall surface area for liquid transport, potentially increasing liquid unloading capacity by 50-300% compared to existing solutions, while minimizing energy loss and preventing static pressure build-up.
Implementation Method 1
At a relatively high gas-liquid ratio, the fluids are transported as an annular flow. Here, the continuous gas phase flows through the center of the pipe and often contains entrained liquid droplets. The liquid phase flows through the annulus formed by the pipe wall and the flowing gas core, along the pipe walls.
Implementation Method 2
Multi-phase flows (liquid-gas-solid) are encountered in various industrial fields such as chemical and process, nuclear reactor, space, geothermal energy and petroleum.
Data Source
AI summary
A pathway section in a tubing system for transporting a gas-liquid flow from a petroleum wellbore to a production point. The pathway section includes a first tubing portion directing the flow towards the production point and a second tubing portion inserted within the first tubing portion, along with other features described herein directing the flow in a manner that makes more wall surface available for liquid transport, which results in a greater liquid lifting capacity, and optimize gas velocity distribution over the cross-section of the pipes, which results in a greater upward shear stress exerted by the gas phase on the liquid phase. Methods of operating and use of the system are also described.