Floating Bushing Seal Housing for Oilfield Leakage
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Solution Overview
Problem
Conventional stuffing boxes in oilfield applications experience leakage due to abrasive particles and poor alignment between the wellhead and the stuffing box, leading to high maintenance costs and environmental issues, especially in heavy crude oil wells.
Innovation Solution
The apparatus includes a stationary housing with a flange collar and a tubular shaft that rotates within the housing, featuring a dynamic seal and a seal compressor part to maintain a reliable seal, with the tubular shaft allowed to float radially and the seal compressor part applying axial force to compress the dynamic seal, and multiple dynamic seals stacked axially for enhanced sealing, along with independent fluid injection and drainage for each seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional stuffing box is used with a fixed shaft mounting, then the structure is simple, but leakage occurs due to poor alignment and wear from abrasive particles
Solution Approach 1:
The tubular shaft is mounted to float radially within the stationary housing, allowing the shaft to dynamically adjust its position to compensate for misalignment between the wellhead and stuffing box. This dynamic adjustment eliminates the need for perfect alignment while maintaining reliable sealing, directly resolving the contradiction between sealing reliability and structural simplicity.
Solution Approach 2:
A floating bushing is introduced as an intermediary element between the tubular shaft and the stationary housing. The bushing allows radial movement of the shaft while maintaining the seal, mediating between the shaft's need for positional adjustment and the housing's requirement for stable sealing contact.
2Reliability
If the tubular shaft is fixed rigidly, then the structure is stable, but wear from abrasive particles and misalignment causes leakage
Solution Approach 1:
The tubular shaft is mounted to float radially within the stationary housing, allowing the shaft to dynamically adjust its position to compensate for misalignment between the wellhead and stuffing box. This dynamic adjustment eliminates the need for perfect alignment while maintaining reliable sealing, directly resolving the contradiction between sealing reliability and structural simplicity.
3Reliability
If a single dynamic seal is used, then the structure is simple, but leakage occurs under high abrasion and pressure
Solution Approach 1:
The sealing system is divided into multiple stacked dynamic seals arranged axially along the tubular shaft. Each seal operates independently to provide multiple sealing stages, enhancing the overall sealing capability against high pressure and abrasion while maintaining manageable structural complexity through modular stacking.
Solution Approach 2:
Multiple dynamic seals are stacked axially along the tubular shaft, extending the sealing function from a single point contact to a distributed multi-stage sealing system. This dimensional extension along the axial direction provides redundant sealing paths that prevent leakage under extreme conditions.
4Reliability
If the seal is compressed axially, then the sealing force increases, but the seal wear accelerates
Solution Approach 1:
The floating tubular shaft allows the seal contact point to dynamically adjust, distributing the sealing force over a longer period and reducing continuous high-stress contact. This dynamic positioning reduces seal wear while maintaining adequate sealing force, extending seal service life.
Solution Approach 2:
Fluid injection ports are provided to inject lubricating or sealing fluid into the seal interface, reducing friction and wear on the dynamic seal while maintaining effective sealing. This hydraulic intervention extends seal life without compromising sealing reliability.
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 configuration significantly reduces leakage by allowing for radial floating of the tubular shaft and axial compression of the dynamic seals, improving seal durability and reducing maintenance costs through efficient sealing and easy maintenance access.
Implementation Method 1
a seal compressor part mounted, within the polished rod passage, to the stationary housing by a threaded fastener, such that as the threaded fastener is advanced, the seal compressor part contacts and applies an axial force upon the dynamic seal to compress the dynamic seal radially inward against the tubular shaft
Implementation Method 2
the tubular shaft is mounted to the apparatus at an anchor point that is at, near, or above, a top end of the stationary housing, with a free base end of the tubular shaft depending from the anchor point to float in radial directions within the polished rod passage
Data Source
AI summary
Seal housings with flange collars, floating bushings, seal compressors, floating polished rods, independent fluid injection to stacked dynamic seals, and related apparatuses and methods of use. Embodiments are described that permit the polished rod to float within a tubular shaft, and the tubular shaft to float within a stationary housing, of a seal housing, to permit the seal housing to accommodate rod deviation from center. Flange collars are provided to facilitate the interconnection between seal housings and driveheads that previously were incompatible with one another.