Expandable Sealing Plunger for Deviated Wellbore Fluid Fallback
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Solution Overview
Problem
Conventional plunger lift systems experience fluid fallback due to insufficient sealing between tubular-shaped plungers and wellbore tubing, leading to liquid loading and reduced hydrocarbon well performance, especially in deviated and vertical wells.
Innovation Solution
A plunger lift assembly with a mandrel, elastic sealing mechanism, and shift rod that adjusts to the wellbore diameter, activating to maintain contact during ascent and deactivating during descent, along with bypass ports to control fluid flow, and a coupler to connect tubing joints, reducing friction and fluid trapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tubular-shaped plungers are used in deviated and vertical wells, then the device structure is simple, but the sealing performance is insufficient causing fluid fallback
Solution Approach 1:
The plunger incorporates an expandable seal mechanism that dynamically adjusts its outer diameter. During descent, the seal remains contracted to minimize friction. Upon activation (e.g., by pressure differential or mechanical trigger), the seal expands radially to engage tightly with the tubing wall, creating an effective seal that prevents fluid fallback while maintaining structural adaptability.
Solution Approach 2:
The plunger utilizes a flexible sealing element (such as an elastomeric or composite material shell) that can deform and conform to the tubing inner surface. This flexible seal mechanism allows the plunger to adapt to slight variations in tubing diameter and maintain reliable sealing contact, eliminating the fluid fallback issue inherent in rigid conventional plungers.
2Reliability
If conventional tubing coupling collars with gaps are used, then the tubing connection is simple, but fluid becomes trapped causing premature wear and breakage
Solution Approach 1:
The invention removes the problematic gap feature from the tubing coupling design. Instead of a traditional collar with internal void space that traps fluid, the coupling is designed with a continuous, gapless bore that allows fluid to flow freely through the connection point, eliminating the trapping mechanism that causes premature wear and failure.
Solution Approach 2:
The coupling acts as an intermediary component that bridges two tubing joints while maintaining fluid continuity. By designing the coupling with a smooth, continuous internal passage rather than a gap-filled structure, it mediates the connection between segments without creating fluid traps, thereby preventing the wear and breakage associated with trapped fluid.
3Reliability
If the sealing mechanism maintains constant contact with tubing wall, then sealing performance is improved, but friction increases causing premature wear
Solution Approach 1:
The sealing mechanism employs dynamic control of contact pressure and contact area. During the descent phase, the seal maintains minimal contact or is slightly retracted to reduce friction and wear. Upon activation for the upward stroke, the seal expands or increases contact pressure to ensure tight sealing and prevent fluid fallback. This dynamic adjustment optimizes both sealing performance and component longevity.
Solution Approach 2:
The sealing mechanism operates in periodic cycles corresponding to the plunger's upward and downward movements. During descent, the seal is in a low-contact state; during ascent, it transitions to a high-contact sealing state. This periodic modulation of sealing intensity ensures effective fluid prevention during critical phases while minimizing cumulative friction and wear over multiple cycles.
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 solution effectively reduces fluid fallback and enhances the efficient lifting of formation fluids to the surface, maintaining well performance by ensuring a strong seal and minimizing premature wear and breakage.
Implementation Method 1
an elastic sealing mechanism... The sealing mechanism may be activated by at least one of pressure in the mandrel chamber and vertical force from movement of the mandrel
Data Source
AI summary
An improved plunger lift assembly, system, and method that can be used in all types of oil and gas wells including those of vertical, highly-deviated, S-curved, or horizontal bores is described. The plunger lift assembly can be part of a plunger lift system used to lift fluid formations out of a wellbore having a production tubing with a drift diameter. The plunger lift assembly may include a mandrel having a chamber, an elastic sealing mechanism, and a shift rod. The sealing mechanism can be disposed about an exterior of the mandrel. The sealing mechanism may be activated by at least one of pressure in the mandrel chamber and vertical force from movement of the mandrel. The shift rod can control fluid flow through the mandrel chamber.