Cross BOP Swivel Joint Rotation During Well Control
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Solution Overview
Problem
During well control events, the engagement of blowout preventers (BOPs) with the drill string prevents rotation, leading to potential differential sticking and costly fishing operations to recover stuck drill strings.
Innovation Solution
The cross BOP swivel joint enables rotation of the drill string by incorporating a swivel housing with internal pipe, journal bearings, and central bearings that allow the internal pipe to rotate relative to the swivel housing, while central bearings provide radial support to prevent deflection and maintain efficient rotation even when BOPs are engaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blowout preventers are engaged with the drill string to seal the annulus during well control events, then fluid flow through the annulus is prevented, but rotation of the drill string is blocked
Solution Approach 1:
The system is divided into two separate rotational interfaces: (1) the swivel housing rotates relative to the wellbore/BOP assembly, and (2) the internal pipe rotates relative to the swivel housing. This segmentation allows the BOP to seal against the stationary swivel housing while the drill string (internal pipe) can still rotate through the bearing-supported relative motion, resolving the contradiction between seal integrity and rotation capability
Solution Approach 2:
The swivel housing acts as an intermediary component between the BOP and the drill string. The BOP seals against the swivel housing outer surface, while journal bearings and central bearings mediate the rotational motion between the swivel housing and internal pipe. This intermediary structure enables simultaneous sealing and rotation by decoupling the sealing interface from the rotation interface
2Reliability
If pressure is exerted by BOPs on the swivel housing to maintain the seal, then sealing is effective, but deflection of the swivel housing radially inward occurs which can interfere with rotation
Solution Approach 1:
The central bearings provide a counterbalancing support structure that opposes the radially inward deflection caused by BOP pressure. The central bearings carry radial loads and prevent the swivel housing from deforming inward toward the internal pipe, maintaining the structural stability needed for effective rotation while allowing the BOP to maintain its sealing pressure
Solution Approach 2:
The system changes the structural parameters of the swivel housing by adding central bearings that modify its load-bearing characteristics. This structural enhancement allows the housing to withstand the radial compression from BOP engagement without excessive deflection, maintaining both seal effectiveness and rotational capability
3Ease of operation
If journal bearings and central bearings are added to enable rotation during well control events, then drill string rotation is maintained, but device complexity increases
Solution Approach 1:
The rotational function is extracted from the traditional BOP-drill string interface and relocated to the bearing-supported interface between the swivel housing and internal pipe. This extraction allows the BOP to focus solely on sealing while the bearing system handles rotation, reducing the complexity burden on the BOP system and enabling independent optimization of each function
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
Enables continuous rotation of the drill string during well control events, reducing the risk of differential sticking and allowing for uninterrupted drilling operations by maintaining efficient rotation and reducing deflection of the swivel housing.
Implementation Method 1
journal bearings and central bearings that reduce friction between the internal pipe and the swivel housing
Data Source
AI summary
A cross BOP swivel joint for crossing over a blowout preventer of a drilling apparatus includes a swivel housing, an internal pipe received through the swivel housing. The internal pipe includes an upper loading shoulder and a lower loading shoulder. The cross BOP swivel joint includes an upper journal bearing, lower journal bearing, and at least one central bearing between the swivel housing and the internal pipe. The central bearings are axially disposed between the journal bearings. When engaged, the BOP contacts the outer surface of the swivel housing of the cross BOP swivel joint. The journal bearings allow the internal pipe to rotate relative to the swivel housing when the BOP is engaged with the swivel housing. This allows rotation of the drill string during well control events. The central bearing provides radial support to the swivel housing to reduce inward deflection of the swivel housing.