Rotating Control Device Sealing System High Pressure
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Solution Overview
Problem
Rotating control devices (RCDs) face limitations in safely operating under high annular wellbore fluid pressures, particularly exceeding 2500 psi, and require a higher safety factor for both static and dynamic ratings to manage pressurized systems in deep offshore wells, while also adhering to API-16RCD standards.
Innovation Solution
A high-pressure rated RCD system is developed by limiting the fluid pressure differential exposed to sealing elements, using a pressurized cavity with sensors to detect and adjust wellbore and cavity fluid pressures and temperatures, and circulating a fluid such as water or drilling fluid to lubricate and cool the system, allowing for surface backpressure application regardless of mud circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If sealing elements are exposed to high wellbore fluid pressure, then the RCD can contain higher pressures, but the sealing elements experience excessive wear and reduced operational life
Solution Approach 1:
The RCD is divided into multiple sealed cavities (first cavity, second cavity, third cavity) with separate sealing elements (first upper, first lower, second upper, second lower sealing elements). Each cavity can be independently pressurized to share the pressure differential load across multiple sealing elements rather than exposing a single sealing element to the full wellbore pressure, thereby extending sealing element life while maintaining high pressure containment capability.
Solution Approach 2:
Pressurized fluid (such as drilling fluid or water) is introduced into the cavities as an intermediary medium to counterbalance the wellbore pressure. This pressurized fluid acts as a mediator that reduces the net pressure differential across each sealing element by providing an opposing pressure force, thereby reducing wear and extending sealing element operational life.
2Reliability
If multiple sealing elements are used to share pressure, then sealing element life is extended, but the device complexity increases
Solution Approach 1:
Multiple sealing elements are combined within a unified RCD housing structure with integrated cavities. The first and second sealing elements are positioned in different cavities but work together as a coordinated system to share the pressure differential. This merging approach distributes the stress across multiple components while maintaining a cohesive device structure, extending sealing element life without proportionally increasing overall device complexity.
3Reliability
If pressurized fluid is circulated through cavities to reduce differential pressure, then sealing element wear is reduced, but energy consumption increases
Solution Approach 1:
The system utilizes the existing drilling fluid circulation system already present in the drilling operation to pressurize the cavities. Rather than requiring a separate energy-intensive pumping system, the RCD integrates with the existing mud circulation infrastructure, allowing the drilling fluid to serve dual purposes: cooling/lubricating the sealing elements and pressurizing the cavities to reduce differential pressure across sealing elements.
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 solution enables RCDs to operate safely under higher pressures, extending the life of sealing elements and allowing for deeper well drilling with larger tubular openings, while using lighter and less expensive drilling fluids, and simplifying the drilling process by disregarding pore pressure limitations.
Implementation Method 1
reduce the differential pressure between the wellbore pressure and the pressurized cavity fluid pressure on the sealing element
Implementation Method 2
circulating a fluid such as water or drilling fluid to lubricate and cool the system
Implementation Method 3
circulating a fluid such as water or drilling fluid to lubricate and cool the system
Data Source
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AI summary
A rotating control apparatus, comprising: an outer member; an inner member having a first sealing element and a second sealing element; said inner member, said first sealing element and said second sealing element rotatable relative to said outer member; a first cavity defined by said inner member, said first sealing element and said second sealing element; and said inner member having a port to said first cavity. Disclosed is also a method for drilling a wellbore in a formation with a fluid, comprising the steps of: casing a portion of the wellbore using a casing having a casing shoe; determining a casing shoe pressure; determining a formation fracture pressure; positioning a rotating control device with said casing; and drilling the wellbore at a fluid pressure calculated using the lesser of the casing shoe pressure and the formation fracture pressure.