Surface BOP Stack for High-Pressure Subsea Well Completion
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Solution Overview
Problem
Conventional drilling and completion equipment and methods are ineffective and uneconomical for drilling and completing high-pressure subsea hydrocarbon wells in deepwater environments, as they often require specialized and costly equipment rated for pressures above 15,000 psi.
Innovation Solution
The method involves removing a conventional BOP stack from the subsea wellhead and coupling a high-pressure riser to the wellhead, allowing for the use of a surface BOP stack for completion and intervention operations, along with a mudline closure device for pressure containment, enabling safe and efficient high-pressure drilling and completion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional BOP stack and conventional riser are used for drilling and completion, then equipment complexity and cost are reduced, but the system cannot handle high-pressure deepwater wells effectively
Solution Approach 1:
The system is divided into two distinct phases: drilling phase using conventional BOP stack and riser, and completion phase using surface BOP stack and high pressure riser. This segmentation allows each subsystem to be optimized for its specific function, with conventional equipment handling drilling and specialized equipment handling high-pressure completion operations.
Solution Approach 2:
The system transitions dynamically between different configurations: conventional BOP stack during drilling, then removal and replacement with surface BOP stack and high pressure riser for completion. This dynamic reconfiguration allows the system to adapt to different operational requirements and pressure conditions.
2Ease of manufacture
If conventional BOP stack is used during drilling, then initial equipment cost is reduced, but subsequent completion operations become complex and costly
Solution Approach 1:
The conventional BOP stack is removed from the subsea wellhead after drilling is complete, extracting it from the system before completion operations begin. This allows replacement with a surface BOP stack and high pressure riser configuration that is optimized for completion operations, reducing the complexity and cost of subsequent operations.
3Reliability
If surface BOP stack and high pressure riser are used for completion, then high-pressure well completion becomes feasible and safer, but initial equipment investment increases
Solution Approach 1:
The conventional BOP stack and conventional riser are used to complete the drilling operation and establish the wellbore first. This preliminary action creates the necessary infrastructure before deploying the more expensive surface BOP stack and high pressure riser for completion operations, allowing phased investment.
Solution Approach 2:
The conventional BOP stack is discarded (removed) from the subsea wellhead after drilling, allowing recovery of investment by not maintaining it during completion operations. Instead, it is replaced with the surface BOP stack and high pressure riser configuration only when needed for completion, optimizing equipment utilization and reducing overall investment.
Data Source
AI summary
For completing a well, and for performing workover or intervention operations with the well, a surface BOP stack is coupled to the subsea wellhead or a subsea tree via a high pressure riser. The well is completed or the workover or intervention operations are performed through the surface BOP stack.