Stuffing Box Pressurized Chamber for Reverse Pressure Sealing
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Solution Overview
Problem
Existing stuffing boxes for sealing rotatable rods in wells face issues with well fluid contamination due to pressure imbalances between the well fluid and the pressurized fluid chamber, particularly when well fluid pressure spikes or the pump pressure drops, leading to reverse pressure differentials that can separate ring seals.
Innovation Solution
A stuffing box design featuring a pressurized fluid chamber with uni-directional seals that allow fluid flow into the chamber, ensuring the ring seals are compressed and preventing contamination, including a method to maintain compression by pressurizing the fluid chamber to match or exceed well fluid pressure and using biasing means like compression springs to keep the seals compressed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fluid chamber is pressurized to exceed well fluid pressure to prevent contamination, then seal protection is improved, but the system becomes vulnerable to reverse pressure differentials when well fluid pressure spikes
Solution Approach 1:
The patent applies dynamics by making the fluid chamber pressure system adaptive rather than static. The pump continuously adjusts fluid chamber pressure in response to well fluid pressure changes, allowing the system to maintain protection against contamination while adapting to pressure spikes. This dynamic adjustment resolves the contradiction between maintaining high pressure for seal protection and handling variable well fluid pressure conditions.
Solution Approach 2:
The patent implements feedback through pressure sensors that monitor both well fluid pressure and fluid chamber pressure. This feedback loop enables the control system to detect pressure differential changes and adjust pump operation accordingly, ensuring the fluid chamber pressure remains sufficient to prevent contamination while responding to real-time pressure conditions. The feedback mechanism directly addresses the vulnerability to reverse pressure differentials.
2Reliability
If the pump operates at high frequency to maintain fluid chamber pressure, then contamination prevention is improved, but energy consumption increases and pump reliability decreases at low speeds
Solution Approach 1:
The patent applies periodic action by operating the pump in intermittent cycles rather than continuously at high frequency. The pump activates only when pressure sensors detect that well fluid pressure is approaching or exceeding fluid chamber pressure, and deactivates when the pressure differential is sufficient. This periodic operation maintains contamination prevention while significantly reducing energy consumption compared to continuous high-frequency operation.
Solution Approach 2:
The patent changes the operational parameters of the pump based on real-time pressure conditions. The pump frequency and power consumption are dynamically adjusted according to the measured pressure differential between well fluid and fluid chamber. When contamination risk is low, the pump operates at reduced frequency or remains idle, optimizing energy usage while maintaining adequate seal protection when needed.
3Reliability
If ring seals are compressed with high force to prevent fluid infiltration, then sealing effectiveness is improved, but ring seals may separate during pressure spikes
Solution Approach 1:
The patent applies the counterweight principle by using the pressurized fluid chamber to provide a counteracting force against well fluid pressure spikes. The fluid chamber pressure acts as a counterbalance that prevents the well fluid pressure from overcoming the ring seal compression and causing separation. This counterpressure mechanism maintains sealing effectiveness while protecting ring seals from structural damage during pressure variations.
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 maintains seal compression and prevents well fluid contamination by ensuring the fluid chamber pressure exceeds the well fluid pressure, even during spikes, using uni-directional seals to manage fluid flow and maintain hydraulic pressure, thus protecting the ring seals.
Implementation Method 1
a pressurized fluid chamber that is pressurized to a pressure exceeding the well fluid pressure under normal operations and thereby exerts a pressure on the ring seals
Implementation Method 2
one or more uni-directional seals arranged below the fluid chamber configured to permit fluid flow into the fluid chamber
Implementation Method 3
the chamber including biasing means for biasing the one or more ring seals against the static seal carrier
Data Source
AI summary
A stuffing box for sealing the end of a rotatable rod is disclosed. The stuffing box includes a sleeve adapted to concentrically receive a portion of the rod therethrough and a tubular pipe concentrically arranged within the sleeve, the rod passing generally concentrically through the pipe, the pipe being in annular spaced relation to the sleeve and the rod. One or more ring seals are arranged between the pipe and the sleeve to prevent the flow of well fluids into the annulus between the sleeve and the pipe. An annular fluid chamber is defined between the sleeve and the pipe below the ring seals. During normal operation, the fluid chamber is pressurized to apply a pressure to the one or more ring seals. One or more uni-directional seals are arranged below the fluid chamber and configured to permit fluid flow into the fluid chamber.