Sealing Element Mounting for Oilfield RCD Wear Reduction
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Solution Overview
Problem
Sealing elements in rotating control devices (RCDs) for oilfield operations experience rapid wear due to pressure and friction loads, leading to potential failure, especially in high-pressure and high-temperature wells, where the existing designs are not robust enough to withstand the stresses caused by drill string movement.
Innovation Solution
A sealing assembly with a support housing and slidable rings that float between stop shoulders and limit structures, reducing end loads by allowing the sealing element to deform and move, combined with a pressure reduction system and nitrogen accumulator to minimize friction and pressure loads, ensuring the sealing element remains in a state of tension and avoids compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing element is mounted to the bearing assembly in the RCD, then the sealing element can perform its sealing function, but the sealing element experiences high end loads and turns inside out during tool joint stripping, leading to damage and rapid wear
Solution Approach 1:
The patent applies the dynamics principle by allowing the sealing element to move axially within the seal holder rather than being rigidly fixed. The sealing element is positioned between a shoulder and a limit structure, enabling it to float and deform in response to varying loads during drill string operations. This dynamic positioning reduces stress concentration and prevents the sealing element from turning inside out under high end loads, thereby improving durability while maintaining sealing function.
2Reliability
If the sealing element is designed to resist turning inside out, then sealing function is maintained, but the sealing element suffers damage near the metal mounting ring due to high pressure and friction loads
Solution Approach 1:
The patent employs the flexible shells and thin films principle by using a resilient sealing element that can deform elastically under pressure. The sealing element is configured to deform in response to tool joint stripping forces, distributing stress away from the metal mounting ring area. This flexibility allows the sealing element to maintain its sealing function while avoiding concentrated damage at the mounting ring, thereby reducing harmful effects from high pressure and friction loads.
3Adaptability or versatility
If the sealing element experiences lateral and axial movement during drill string operations, then the sealing element can adapt to tool joint stripping, but the movement causes deformation and wear on the seal elements
Solution Approach 1:
The patent applies beforehand cushioning by providing a limit structure within the seal holder that prevents excessive axial movement of the sealing element. The sealing element is allowed to float and deform within controlled limits, cushioning the impact of tool joint stripping forces before they can cause damaging deformation. This pre-configured movement limitation extends the service life of the sealing element while maintaining adaptability to normal operational 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 significantly reduces wear and tear on sealing elements by minimizing end loads and pressure loads, preventing damage and maintaining effective sealing performance even under high stress conditions, thereby enhancing the durability and reliability of the RCDs.
Implementation Method 1
the sealing element will turn inside out during this motion. A properly designed sealing element will resist turning inside out, but may suffer damage near its metal mounting ring
Implementation Method 2
Each ring is configured for slidable movement along the inner wall of the support housing
Data Source
AI summary
A sealing assembly for sealing against a piece of oilfield equipment in a wellbore. The sealing assembly has a support housing and the support housing defines an inner wall and a port configured for fluid communication with the wellbore. Such inner wall defines a stop shoulder, and the support housing has a limit structure proximate one or both end(s). A sealing element is contained within the support housing. A ring is connected to the sealing element at one or both end(s). Each ring is configured for slidable movement along the inner wall of the support housing and further configured to float between the stop shoulder and the limit structure.