Compact Subsea Cutting System Asymmetrical Gate Design
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Solution Overview
Problem
Bulky and heavy Blowout Preventer (BOP) stacks are costly and inefficient for offshore operations, requiring significant maintenance and limiting the number of wells that can be economically reworked due to space constraints and high maintenance costs, with issues of cut pipe getting stuck within the BOP stack.
Innovation Solution
A compact cutting system with asymmetrical gate operation, utilizing a housing with two gates where one gate is movable between open and closed positions to seal the throughbore, and the other between open and partially open positions to centralize and cut the pipe, reducing the need for sealing and minimizing fluid volume, allowing for efficient cutting of drill pipe, coiled tubing, and wireline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional BOP stacks are used for cutting pipe, then cutting function is achieved, but the system becomes bulky and heavy requiring significant space and lifting equipment
Solution Approach 1:
The BOP stack is segmented into separate functional components: a gate valve for sealing and a独立的 cutting device with cutting elements. This segmentation allows each component to be optimized independently, reducing the overall weight and size of the system while maintaining the cutting function.
Solution Approach 2:
The gate valve is designed to serve multiple functions: it provides sealing capability and integrates cutting elements to perform pipe cutting. This multi-functionality eliminates the need for separate heavy-duty BOP stacks, reducing weight and space requirements.
2Reliability
If traditional BOP stacks are used for cutting pipe, then cutting function is achieved, but maintenance costs increase and maintenance frequency increases
Solution Approach 1:
The cutting elements are extracted as separate, replaceable components from the gate valve body. This allows cutting elements to be easily removed and replaced without replacing the entire BOP stack, significantly reducing maintenance costs and frequency.
Solution Approach 2:
Worn or damaged cutting elements can be discarded and replaced with new ones, while the main gate valve body is retained and reused. This selective replacement strategy reduces maintenance costs compared to replacing entire BOP stacks.
3Reliability
If traditional BOP stacks are used for cutting pipe, then cutting function is achieved, but cut pipe may become stuck within the BOP stack blocking other operations
Solution Approach 1:
Instead of attempting to push cut pipe through the BOP stack, the design allows cut pipe to be pushed out by the closing gate. The gate closes onto the cut pipe end and pushes it out of the throughbore, preventing blockage and ensuring operation continuity.
4Weight of stationary object
If compact cutting system with asymmetrical gate operation is used, then weight is reduced and space is saved, but device complexity increases
Solution Approach 1:
The gate valve employs asymmetrical operation where one gate moves fully across the throughbore for sealing, while the other gate moves only partially to perform cutting. This asymmetrical design reduces the stroke length and size of hydraulic cylinders, thereby reducing overall system weight and space while the mechanical guidance ensures operation simplicity.
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 compact cutting system effectively cuts drill pipe and tubing with reduced maintenance needs, weighs less than traditional BOPs, and operates with less hydraulic fluid, enabling cost-effective reworking of wells and substitution in intervention packages.
Implementation Method 1
The first gate includes a first gate cutting element and the second gate includes a second gate cutting element so that when the first gate is in the partially open throughbore position and the second gate is in the closed throughbore position, then any pipe in the throughbore is cut.
Implementation Method 2
when the first gate is in the partially open throughbore position and the second gate is in the closed throughbore position, then any pipe in the throughbore is cut
Data Source
AI summary
A subsea compact cutting system operable for cutting pipe utilizing two gates. Each gate preferably has a blanking portion and an opening through the gate. A first gate is moveable only between an open throughbore position and a partially open throughbore position. A second gate is moveable between an open throughbore position and a closed throughbore position. To cut pipe and seal off the throughbore, the first gate is moved to a position where a cutting element on the first gate is centrally located in the throughbore. The second gate moves to seal the throughbore. A cutting element on the second gate interacts with the cutting element on the first gate to cut pipe in the throughbore.