Non-sealing V-shaped Casing Shear Rams
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Solution Overview
Problem
Current Blow Out Preventers (BOPs) with shear rams are unable to effectively shear 9⅝″ casing using a 13⅝″ BOP, requiring larger BOPs that increase complexity, cost, and time for drilling operations, necessitating equipment swaps during production.
Innovation Solution
Non-sealing casing shear rams with V-shaped cutter blades and specific rake angles, allowing for the cutting of casings with an outer diameter at least 25% less than the BOP opening, eliminating the need for seals and enabling the use of a smaller BOP for both drilling and production by centering and cleanly shearing pipes within the bore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a larger BOP is used to shear 9⅝″ casing, then the shearing capability is improved, but the device complexity and cost increase
Solution Approach 1:
The invention changes the geometric parameters of the shear rams, specifically using a V-shaped configuration with optimized angles and a back rake angle between 7-25 degrees. This allows the shear rams to effectively cut 9⅝″ casing within a smaller 13⅝″ BOP opening, eliminating the need for larger equipment while maintaining shearing capability
Solution Approach 2:
The shear rams are designed with segmented cutting edges featuring a V-shape configuration. The cutting edge is divided into multiple surfaces including a first surface, second surface, and third surface, each at specific angles. This segmentation allows the cutting action to be distributed across multiple surfaces, enabling effective cutting of large diameter casing in a smaller BOP
2Reliability
If sealing components are added to the shear rams, then the isolation capability is improved, but the device complexity increases
Solution Approach 1:
The invention extracts and removes sealing components from the shear ram assembly. The patent explicitly states that the shear rams operate without seals or other sealing components, relying instead on the mechanical cutting action and the containment capabilities of the BOP structure itself to provide isolation
Solution Approach 2:
The invention uses a simpler, seal-less design that prioritizes the primary shearing function. Rather than incorporating expensive and complex sealing systems, the design accepts that the shear rams are single-use components that are replaced after cutting operations, eliminating the need for maintenance of sealing components
3Productivity
If the BOP opening is reduced in size, then the equipment cost and time are reduced, but the shearing capability for large casing is limited
Solution Approach 1:
The invention optimizes the geometric parameters of the shear rams including the V-shape angle, back rake angle (7-25 degrees), and the arrangement of cutting surfaces. These parameter changes enable the shear rams to effectively cut casing with outer diameter at least 25% less than the BOP opening diameter, allowing a 13⅝″ BOP to cut 9⅝″ casing
Solution Approach 2:
The invention introduces a three-dimensional V-shaped geometry to the cutting surfaces, utilizing multiple angular surfaces (first surface, second surface, third surface) rather than simple planar cutting edges. This dimensional approach allows the shear rams to engage and cut large diameter casing effectively within the constrained space of a smaller BOP opening
Data Source
AI summary
Non-sealing casing shear rams are utilized in a blow out preventer (“BOP”) for shearing or cutting casing, but do not seal. The BOP with non-sealing casing shear rams with V-shaped blades has the shearing capabilities of a larger shear ram BOP while utilizing a smaller sized BOP to reduce the need for additional time, expense, and equipment. The non-sealing casing shear ram BOP may be used for drilling operations and during production without the need for swapping a larger shear ram BOP used for drilling to a smaller shear ram BOP for operations. The V-shape blade and back rake angle of the non-sealing casing shear ram blades produce the shearing force of the larger BOP in a smaller sized BOP.