Concentric Mandrel Assembly for Deepwater Chemical Injection
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Solution Overview
Problem
Existing chemical injection mandrels in deep water wells are prone to plugging due to small internal diameters and lack of effective filtration, leading to loss of functionality, production losses, and increased maintenance costs, especially in extreme hydrostatic pressures.
Innovation Solution
A concentric mandrel assembly with a concentric jacket and mandrel tube design that eliminates the need for injection valves, creating an annular space for chemical flow and incorporating a pressurization device with check valves and a rupture disc to prevent column breakage and ensure stable chemical injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemical injection valves with small internal diameter are used, then chemical injection precision is improved, but plugging risk increases
Solution Approach 1:
The injection system is divided into multiple injection ports distributed along the mandrel, with each port having a relatively large diameter. This segmentation allows adequate chemical dosing while avoiding the plugging issues of single small-diameter valves
Solution Approach 2:
The traditional chemical injection valve component is completely removed from the system. Instead, chemicals are injected directly through injection ports in the mandrel, eliminating the small internal diameter valve that causes plugging
2Productivity
If hydraulic lines are used to transport chemicals, then chemical delivery capability is improved, but string breakage risk increases
Solution Approach 1:
The hydraulic line system is completely removed from the downhole injection system. Chemicals are injected directly through the mandrel body, eliminating the hydraulic lines that create hydrostatic pressure and string breakage risks
Solution Approach 2:
The mandrel body itself serves as the intermediary for chemical injection, replacing the hydraulic line system. The mandrel's structure directly enables chemical delivery without requiring separate hydraulic transport lines
3Measurement precision
If injection valves are used for chemical dosing, then dosing accuracy is improved, but maintenance requirements increase
Solution Approach 1:
The injection valve component is removed entirely, eliminating the main source of maintenance issues. Chemical dosing is achieved through simple injection ports in the mandrel body that require no maintenance
Solution Approach 2:
The injection ports are designed as simple, maintenance-free features of the mandrel body rather than complex valves requiring periodic maintenance and replacement
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 design reduces the likelihood of plugging, maintains well production by preventing scale formation, and lowers maintenance and resource costs by ensuring continuous chemical injection and reducing the need for critical resources like stimulation vessels.
Implementation Method 1
the liquid column formed within the hydraulic line creates a hydrostatic pressure which, when this column reaches a certain pressure, occurs a discharge of liquid from the inside of the line
Data Source
AI summary
The present invention refers to a mandrel assembly for chemical injection in use in an oil well production string where the water depth can reach 3,000 m, exerting extreme hydrostatic pressures on the mandrel. The mandrel assembly is capable of dosing the chemical fluid flow rate to avoid some types of unwanted situations in the production string, mainly related to fouling. It has the characteristic of not using injection valves having small diameters, causing the annular space between the mandrel body and the inner part to ensure greater space for the flow of chemical fluid, thus reducing the likelihood of a possible plugging. Such characteristics ensure lower maintenance interventions, thus generating lower costs and increasing well reliability.