Free Piston Assembly Flow Restriction Member
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Solution Overview
Problem
Conventional plunger lift systems require shutting in gas wells to allow the piston to fall, leading to liquid accumulation and well loading, and previous attempts at valved bypasses have been intricate and unsuccessful, while multi-part free piston assemblies face issues with latching and component reunion, resulting in inefficiencies and potential well stoppage.
Innovation Solution
An improved free piston assembly with a sleeve member and flow restriction member, where the flow restriction member is retained by formation fluid forces and released by a pressure drop, allowing axial movement and preventing premature release, and a sensor-adjusted cycle to optimize liquid retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plunger lift systems shut in gas wells to allow the piston to fall, then the piston can be positioned at the bottom of the well, but liquid accumulates and the well loads up, reducing productivity
Solution Approach 1:
A flow restriction member (ball) is introduced as an intermediary element that mediates between the piston and the well flow. The ball is held in a restricted position by formation fluid pressure during normal production, allowing continuous flow. When pressure drops (well loading), the ball moves to an unrestricted position, signaling piston arrival without requiring well shutdown.
Solution Approach 2:
The system uses the well's own formation fluid pressure to control the flow restriction member's position. During normal production, formation pressure automatically holds the ball in the restricted position. When the well loads up and pressure drops, the ball automatically moves to indicate piston arrival, eliminating the need for external control systems or well shutdown procedures.
2Productivity
If multi-part free piston assemblies are used to maintain well flow, then productivity is improved, but issues with latching and component reunion occur, reducing reliability
Solution Approach 1:
The flow restriction member is extracted as a separate, movable component from the piston assembly. This allows it to independently respond to pressure changes and provide a reliable signal of piston arrival without being mechanically connected to the piston, eliminating latching issues while maintaining component functionality.
Solution Approach 2:
The system uses pneumatic/hydraulic pressure (formation fluid pressure) to control the position of the flow restriction member. The pressure differential automatically positions the ball in restricted or unrestricted states, providing reliable component interaction without mechanical latching mechanisms.
3Productivity
If valved bypasses are implemented to prevent liquid accumulation, then well flow continuity is improved, but the device becomes intricate and complex, reducing ease of operation
Solution Approach 1:
The complex valved bypass system is replaced by extracting the essential function (flow restriction and signaling) into a simple, passive flow restriction member. This eliminates intricate valve mechanisms while achieving the same goal of preventing liquid accumulation and signaling piston arrival.
Solution Approach 2:
The flow restriction member operates passively using formation fluid pressure to control its position. It automatically restricts flow during normal production and opens when pressure drops, providing well flow continuity management without complex control systems or operational intervention.
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 improved assembly maintains well flow by preventing liquid accumulation, reduces downtime, and optimizes liquid retrieval, enhancing the efficiency and longevity of gas well production.
Implementation Method 1
the flow restriction member is retained by formation fluid forces and released by a pressure drop
Implementation Method 2
Gas flowing upwardly in the flow paths around the separation rod and sleeve include cooperating sections that produce a pressure drop sufficient to hold the plunger sleeve in the well head against the effect of gravity
Implementation Method 3
the piston is not attached to a reciprocating member, but rather relies on fluids and fluid pressure to provide lift the piston components
Data Source
AI summary
An improved free piston assembly for use in combination with a plunger lift assembly is provided. The piston assembly includes a sleeve member, a retention sleeve, and a flow restriction member. The sleeve member has an inner surface defining an opening for the flow of formation fluids. The opening includes a first section and a second section. The retention sleeve is configured to be affixed to the first section of the opening. The flow restriction member is not latched to the sleeve member and is configured to have an interference fit with the retention sleeve. The interference fit provides a force that is sufficient to overcome the force of gravity on the flow restriction member when formation fluid forces acting on the flow restriction member are decreased or removed. The second section of the opening is configured to prevent the passage of the flow restriction member.