Negative Accumulator for Subsea BOP Shear Ram Force
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Solution Overview
Problem
Contemporary blowout preventer systems in subsea environments are limited in their ability to shear larger, higher strength materials such as drill pipe tool joints due to insufficient shearing force, which is essential for emergency well bore closure and environmental protection.
Innovation Solution
Connecting a low or negative pressure accumulator to the low-pressure side of the pistons operating the shear rams, leveraging ambient subsea pressure to increase the differential force available for shearing, thereby enhancing the system's capability to cut through thicker cross-section pipes and tool joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional pressure accumulators are used to operate shear rams, then the system can function with standard pressure sources, but the shearing force is insufficient to cut through thicker cross-section pipes and tool joints
Solution Approach 1:
The patent applies negative pressure (vacuum) on the low-pressure side of the piston instead of using only positive pressure. This inverts the conventional approach by creating a pressure differential that pulls the piston in addition to pushing it, thereby doubling the effective force available for shearing without requiring a proportional increase in the accumulator's pressure rating.
Solution Approach 2:
The patent changes the pressure parameter from single-sided positive pressure to dual-sided pressure differential (positive on one side, negative on the other). This parameter change effectively doubles the force output while maintaining the same accumulator pressure rating, enabling the system to cut through higher strength materials like drill pipe tool joints.
2Force
If the accumulator pressure is increased to provide sufficient shearing force, then the shearing capability improves, but the risk of exceeding the piston seal pressure rating increases
Solution Approach 1:
Instead of increasing the pressure on the positive side beyond the seal rating, the patent applies negative pressure on the low-pressure side. This allows the system to achieve doubled force output while keeping the positive pressure within the original seal rating limits, thereby avoiding the risk of exceeding maximum pressure ratings.
3Force
If larger accumulators with higher pressure capacity are used, then sufficient shearing force can be achieved, but the device complexity and cost increase
Solution Approach 1:
The patent utilizes the existing ambient subsea pressure environment as a resource. By connecting the low-pressure side of the piston to the ambient environment, the system automatically harnesses the pressure differential without requiring additional active components, complex control systems, or external power sources.
Solution Approach 2:
The patent introduces a simple valve mechanism as an intermediary to control the connection between the accumulator and the low-pressure side of the piston. This simple intermediary component enables the complex function of negative pressure application without requiring a complex overall system design.
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
This solution doubles the shearing force, significantly improving the system's ability to secure the well bore in emergency situations by effectively cutting through thicker materials, enhancing safety and operational reliability.
Implementation Method 1
Connecting a low or negative pressure accumulator to the low pressure side of the pistons operating blowout preventer rams in a high pressure subsea environment to increase the shearing force
Data Source
AI summary
The method of providing increased motive force for one or more rams of a subsea blowout preventer comprising providing a one or more pistons connected to the one or more ram, the pistons having a distal side and a proximate side with respect to the ram, providing a tank contain a first pressure less than the ambient pressure of seawater at the location of the subsea blowout preventer, and communicating the first pressure with the proximate side of the one or more pistons to cause or enhance the differential pressure across the one or more pistons to urge the rams toward the center of the bore of the subsea blowout preventer.