Multi-section subsea tree for selective valve servicing
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Solution Overview
Problem
Current well maintenance practices, particularly for offshore wells, are inefficient and costly due to the need to remove and reinstall either vertical or horizontal trees, which often require unreliable downhole valves and extensive use of heavy lifting equipment, leading to increased time and expense, especially when predicting future maintenance needs is challenging.
Innovation Solution
The multi-section tree system allows for independent removal and servicing of the completion and valve section without removing the entire tree from the wellhead, utilizing hydraulically operated collet connectors and a passive vertical orientation sleeve to align and lock the tubing hanger, enabling surface-controlled subsurface safety valves and reducing the need for robust equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vertical or horizontal trees are used with traditional well completion systems, then the well can be completed for production, but maintenance and servicing require removal and reinstalling of the entire tree, increasing time and cost
Solution Approach 1:
The tree assembly is divided into separate sections: a first section with a first connection interface and a second section with a second connection interface. This segmentation allows the tree to be assembled in sections and enables selective removal of individual sections for maintenance without removing the entire tree, thereby reducing maintenance time and improving productivity.
2Reliability
If traditional tree systems are used, then the well can be controlled, but robust lifting equipment is required for removal and installation operations
Solution Approach 1:
By segmenting the tree into removable sections with standardized connection interfaces, the system enables maintenance operations without requiring robust lifting equipment. The lighter, modular sections can be handled with simpler equipment while maintaining well pressure control through the sealed connections between sections.
3Ease of repair
If the entire tree is removed for maintenance, then components can be serviced, but the well is left vulnerable and requires lengthy plugging and killing operations
Solution Approach 1:
The tree is segmented into removable sections that can be independently serviced. This allows maintenance personnel to access and service specific components without removing the entire tree, thereby reducing well vulnerability and eliminating the need for lengthy plugging and killing operations while still enabling effective component servicing.
4Reliability
If downhole valves are used for pressure control, then the well can be shut in during emergencies, but the valves may be unreliable due to lack of recent use or testing
Solution Approach 1:
The tree assembly is segmented into removable sections with external valves and control mechanisms. This segmentation allows the valves to be accessed, tested, and serviced from the surface without removing the entire tree, enabling regular maintenance and testing that improves reliability while making the valve status detectable and measurable through external monitoring.
Data Source
AI summary
A subsea well production system for a well including a subsea wellhead. The system includes a multi-section production tree that includes a landing section engageable with the subsea wellhead and including a landing section bore. The tree also includes a valve section separate from and engageable with the landing section, the valve section including a lateral production port extending through a valve section wall and in communication with a valve section bore. A production tubing supported by a tubing hanger is installed and supported in the landing section bore such that the tubing hanger extends into the valve section bore. The tubing hanger and production tubing are retrievable through the section bores without disengaging the valve section from the landing section. The valve section is also disengageable from the landing section with the tubing hanger remaining in the landing section.