Open Water Lubricator for Riserless Wellbore Cap Replacement
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Solution Overview
Problem
Current methods for accessing subsea Christmas trees with solid body internal tree caps require deploying large and costly equipment, such as blowout preventers and drilling risers, to maintain pressure control and perform wellbore interventions, whereas internal tree caps with access bores can be replaced more efficiently using lighter intervention systems, but there is a need to replace solid body caps with access bore caps to reduce costs and enhance intervention flexibility.
Innovation Solution
A cap replacement system comprising an open water lubricator with a piston assembly and a well control package that allows for the removal and installation of internal tree caps, maintaining verifiable pressure barriers and enabling the use of riserless light well intervention systems, which includes a tell-tale assembly and linear actuator for engaging and disengaging tree caps, and a method for replacing internal tree caps while ensuring pressure integrity and reducing equipment needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid body internal tree caps are used, then well control barriers are maintained, but large and costly equipment (blowout preventer and drilling riser) is required for access
Solution Approach 1:
The internal tree cap is segmented into two parts: a solid body cap portion that maintains well control barriers, and a separate access bore that allows intervention access. This segmentation enables the cap to provide both safety containment and operational access functions simultaneously, eliminating the need for large retrieval equipment.
Solution Approach 2:
An access bore is extracted from the internal tree cap structure, creating a dedicated passage for wellbore interventions. This extraction allows lighter intervention equipment to access the wellbore without requiring complete cap removal, thereby reducing the size and cost of required equipment while maintaining well control.
2Adaptability or versatility
If solid body internal tree caps are replaced with access bore caps, then intervention flexibility is enhanced, but pressure containment requirements must be maintained
Solution Approach 1:
The internal tree cap exhibits local quality by having different functional zones: the solid body portions maintain pressure containment and well control barriers, while the access bore provides localized intervention access. This spatial differentiation of properties allows the cap to simultaneously provide both pressure containment and intervention flexibility.
Solution Approach 2:
The access bore is pre-configured in the internal tree cap design, allowing intervention equipment to access the wellbore through the cap structure before any issues arise. This preliminary configuration enables proactive maintenance and intervention operations while maintaining pressure containment, enhancing both flexibility and reliability.
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 replacement of solid body internal tree caps with access bore caps, reducing costs and intervention time, allowing for flexible wellbore operations without the need for large rigs, and maintaining multiple pressure barriers for safety, thus enhancing operational efficiency and reducing the risk of wellhead damage.
Implementation Method 1
The piston assembly may include internal and/or external hydraulic lines and a hydraulic manifold may be configured for one or more methods of providing linear translation of the piston assembly
Implementation Method 2
The piston assembly is configured to extend through the well control package, such as into a Christmas tree or other portions of a wellbore to perform a wellbore operation
Implementation Method 3
The tell-tale assembly may include: a housing, a tell-tale rod disposed within the housing, a rotary actuator configured to rotate the piston assembly and/or a running tool
Implementation Method 4
The well control package may include at least one valve configured to seal a central bore of the system
Implementation Method 5
The interior of the system may also include at least one verifiable (testable) pressure barrier
Implementation Method 6
The linear actuator assembly may include: a linear actuator housing, a piston disposed within the actuator housing and connected to a lower end of the tell-tale rod
Data Source
AI summary
A system is provided to perform various wellbore operations, including retrieval and replacement of solid internal tree caps, for example. The system may include an open water lubricator having a piston assembly disposed therein. The system may also include a well control package connected to a distal end of the open water lubricator. The piston assembly is configured to extend through the well control package. Method using systems disclosed herein may be performed while maintaining at least two testable pressure barriers during each of the retrieving and replacement steps.