Concentric Riser Pressure Management for Deepwater Drilling
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Solution Overview
Problem
Existing marine riser systems for deep water offshore drilling face challenges in pressure management, requiring significant time and cost for deployment and operation, with limitations in burst pressure capacity and potential for eccentric side loading due to disassembly and primary well control function unavailability.
Innovation Solution
A concentric riser system with fluid inlet and outlet conduits, annular seals, and a rotating control device that allows for efficient management of fluid density and control of influxes, enabling dual gradient and annular drilling capabilities without substantial disassembly, using a concentric riser support body with actuable seals and fluid conduits for precise pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a concentric inner riser is deployed using existing methods, then pressure management capability is improved, but deployment time and cost increase significantly due to substantial disassembly requirements
Solution Approach 1:
The patent implements a nested concentric riser configuration where an inner riser is positioned within an outer riser, both extending from the wellhead to the subsea BOP. This nested structure enables dual gradient and annular drilling capabilities without requiring disassembly of the marine riser system, thereby reducing deployment time while maintaining pressure management functionality.
Solution Approach 2:
The concentric riser system is designed to perform multiple functions: it enables dual gradient drilling, annular drilling, and maintains primary well control capability through the existing BOP. The system integrates fluid inlet/outlet conduits and annular seals to handle various drilling modes without requiring separate equipment deployments.
2Reliability
If the marine riser system is substantially disassembled for concentric riser deployment, then pressure control capability is enhanced, but operational cost increases
Solution Approach 1:
The nested concentric riser design allows the inner riser to be deployed within the existing outer riser structure without complete disassembly. This reduces installation complexity and operational costs while maintaining the reliability needed for effective pressure control during drilling operations.
Solution Approach 2:
The riser system is segmented into functional components (inner riser, outer riser, annular seals, fluid conduits) that can be independently configured and deployed. This segmentation allows for modular installation and maintenance, reducing overall operational costs while ensuring reliable pressure control through dedicated sealing and fluid management systems.
3Adaptability or versatility
If the upper end of the marine riser is unpinned from the rig, then deployment flexibility is improved, but differential movement causes eccentric side loading of annular sealing elements
Solution Approach 1:
The patent incorporates a pinning mechanism at the upper end of the marine riser that is pre-configured to engage with the rig structure. This preliminary positioning action ensures the riser remains pinned to the well centerline before drilling operations begin, preventing differential movement and eccentric side loading of annular sealing elements while still allowing deployment flexibility.
4Ease of operation
If the upper annular BOP is used to seal and isolate the annulus for concentric riser deployment, then installation is simplified, but the primary well control function becomes unavailable
Solution Approach 1:
The system design allows the upper annular BOP to serve dual purposes: it can seal and isolate the annulus during concentric riser installation, and simultaneously maintain readiness for primary well control functions. The configuration ensures that well control capability is not compromised during deployment operations.
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 enables efficient prevention of blowouts and manages pressure effectively during drilling through formations with pressurized fluids, reducing operational time and cost while maintaining the primary well control function, enhancing safety and efficiency.
Implementation Method 1
a riser annular seal within the tubular body that is configured to sealingly engage a concentric tubular member when the seal is actuated
Implementation Method 2
These elements work in cooperation to manage the fluid density in the riser and to control influxes of abnormally pressurized fluids into the risers
Implementation Method 3
the drilling system employs a main marine riser having a plurality of fluid inlet and outlet conduits, concentric inner riser supported within the main marine riser
Data Source
AI summary
A drilling system employing a main tubular having a plurality of fluid inlet and outlet conduits positioned thereon and a concentric inner tubular having a plurality seals for sealing the annular space between the concentric inner and main tubulars. The fluid inlet and outlet conduits work in cooperation with the annular seals to selectively open and close for effective management of pressure within the tubulars.