Riser Internal Rotating Flow Control Device Pressure Seal
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Solution Overview
Problem
Conventional offshore drilling riser configurations face safety risks due to inadequate pressure control, as the surface BOP and RFCD may not effectively manage sudden releases of pressurized fluids, potentially exceeding the pressure rating of the riser and exposing the drilling platform to danger.
Innovation Solution
A system for securing a rotating flow control device (RFCD) within the riser pipe section below the slip joint, utilizing a latch assembly with radially moveable lock dogs and a seal assembly actuated by fluid pressure, to create a pressure seal and isolate pressurized wellbore returns, thereby enhancing pressure integrity and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surface BOP and surface RFCD are used to control pressurized fluids, then pressure control is provided at the drilling platform level, but the drilling platform is exposed to dangerous risk if pressure exceeds riser rating
Solution Approach 1:
The invention divides the pressure control function into two segments: surface-level control (drilling platform) and subsurface-level control (within the riser). The RFCD is positioned within the riser below the slip joint to provide a secondary pressure seal, creating segmented pressure zones that isolate the drilling platform from high-pressure risks while maintaining control capability at both levels.
Solution Approach 2:
The RFCD positioned within the riser acts as an intermediary pressure barrier between the pressurized wellbore returns and the drilling platform. This intermediate device provides an additional layer of protection by containing pressurized fluids at a subsurface level, preventing direct exposure to the drilling platform while still allowing controlled management of pressure conditions.
2Reliability
If the RFCD is positioned below the slip joint to create pressure seal, then pressure integrity is improved, but the device must be securely installed within the riser
Solution Approach 1:
The RFCD is nested within the existing riser structure, specifically positioned within the riser pipe section below the slip joint. This nested configuration allows the pressure control device to be integrated into the existing riser architecture without requiring external modifications or complex external mounting structures, simplifying installation while maintaining pressure integrity.
Solution Approach 2:
The invention uses a standard flanged connection design that replicates conventional riser coupling methods. The RFCD incorporates flanges that match standard riser flange specifications, allowing it to be installed using existing riser assembly procedures and tools, thereby reducing installation complexity while achieving the required pressure seal.
3Productivity
If conventional surface equipment is used to handle wellbore returns, then the drilling platform can manage returns, but capacity may be inadequate for sudden releases
Solution Approach 1:
The RFCD positioned within the riser performs preliminary containment of pressurized wellbore returns before they reach the surface equipment. By establishing a pressure seal at the subsurface level, the system preemptively manages pressure buildup and sudden releases, preventing overload conditions that would exceed surface equipment capacity and compromising safety margins.
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 system provides a robust pressure seal and containment of pressurized returns at a subsurface level, reducing the risk to the drilling platform and increasing the riser's pressure integrity from 500 psi to up to 2000 psi, ensuring safer operations and environmental protection.
Implementation Method 1
a seal assembly actuated by fluid pressure, to create a pressure seal and isolate pressurized wellbore returns
Implementation Method 2
a latch assembly with radially moveable lock dogs and a seal assembly actuated by fluid pressure
Data Source
AI summary
A riser pipe system for releasably securing a rotating flow control device internally within a riser string for use in offshore drilling can include a riser pipe section, a removable latch assembly for releasably securing the RFCD, and optionally, a removable seal assembly for sealing against the RFCD. The latch and seal assemblies are disposed within the riser pipe section and axially restrained by at least one removable retaining member. The latch assembly and seal assembly may be hydraulically or pneumatically actuated together or separately.