Arcuate Control Line Encapsulation for Annular Seal Integrity
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Solution Overview
Problem
Conventional control line encapsulation profiles fail to achieve an effective seal across the abrupt edges and recesses of annular blowout preventers (BOPs), leading to reduced pressure differential ratings and potential hazards and costly recovery operations.
Innovation Solution
An encapsulation body with an arcuate first surface and a geometrically continuous second surface is used to encase control lines on the outer surface of a tubular, facilitating a seal between the encapsulation body and the tubular, and an annular barrier device is activated to occupy the annular space between the drilling riser casing and the tubular, ensuring a secure seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control line encapsulation profiles are used, then control lines can be positioned on the outer surface of tubulars, but the pressure differential rating of annular BOPs is drastically reduced due to inability to form effective seals across abrupt edges and recesses
Solution Approach 1:
The encapsulation body employs a curved, arcuate outer surface that conforms to the cylindrical geometry of the tubular, eliminating abrupt edges and recesses. This curvature allows the annular BOP sealing element to make continuous contact with the encapsulation body, forming an effective seal and restoring the pressure differential rating.
Solution Approach 2:
The invention changes the geometric parameters of the encapsulation profile from conventional flat or angular designs to a specifically engineered curved profile with controlled radius of curvature. This parameter change ensures compatibility with annular BOP sealing surfaces while maintaining control line protection.
2Reliability
If conventional encapsulation profiles with abrupt edges and recesses are used, then control lines are protected, but activation of blind and shear ram BOPs becomes necessary which poses hazards and results in costly operations
Solution Approach 1:
The curved encapsulation profile proactively prevents the seal failure condition that would trigger blind or shear ram BOP activation. By eliminating abrupt edges and recesses before they can cause sealing problems, the design anticipates and prevents the harmful sequence of events.
Solution Approach 2:
The encapsulation body is pre-configured with the optimal curved geometry that ensures proper sealing engagement with annular BOPs before any emergency situation arises. This preliminary design configuration eliminates the need for corrective actions during emergency operations.
3Ease of operation
If control lines are positioned on the outer surface of tubulars, then energy and information can be conveyed to downhole locations, but the annular space sealing is compromised due to irregular encapsulation surfaces
Solution Approach 1:
The encapsulation body exhibits different surface qualities at different locations: the outer surface is curved to match the tubular geometry for sealing purposes, while the inner surface is configured to accommodate and protect the control lines. This local differentiation of surface properties satisfies both sealing and control line protection requirements.
Data Source
AI summary
Control lines on the outer surface of a tubular disposed within a drilling riser casing may be encapsulated to facilitate formation of a seal in an annular space defined by an inner surface of the drilling riser casing and an outer surface of the tubular. More specifically, an encapsulation body may be configured to at least partially encase control lines. The encapsulation body may include a first surface and a second surface. The first surface may have an arcuate shape that corresponds to the outer surface of the tubular to facilitate formation of a seal between the first surface of the encapsulation body and the outer surface of the tubular when the first surface of the encapsulation body abuts the outer surface of the tubular. The second surface may be shaped to provide a geometrically continuous periphery about the tubular and the encapsulation body when the first surface of the encapsulation body abuts the outer surface of the tubular.