Nested Cylinder Compact Blowout Preventer Design
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Solution Overview
Problem
Conventional ram-type blowout preventers are large in size due to their elongated housing and separate actuator cylinders, requiring expensive surface vessels with large rotary tables to accommodate them.
Innovation Solution
A compact blowout preventer design featuring a nested cylinder actuator and ram system, where the ram and actuator cylinders are combined, and the piston area is increased with a second nested cylinder, allowing for a smaller outer diameter and enhanced actuating force through hydraulic pressure distribution across multiple piston chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional separate actuator cylinders and ram housing are used, then the BOP can provide sufficient actuating force, but the overall outer diameter becomes very large requiring expensive surface vessels with large rotary tables
Solution Approach 1:
The patent applies nesting by placing the actuator piston inside the ram housing, and the ram inside the BOP housing. Specifically, the actuator piston is received within the ram housing cavity, allowing the actuating mechanism to be contained within the existing ram structure rather than requiring separate external cylinders. This nested arrangement reduces the overall outer diameter envelope while maintaining sufficient actuating force capability
Solution Approach 2:
The patent merges the actuator cylinder and ram housing into a single integrated structure. The ram housing serves dual functions as both the containment for the ram and the housing for the actuator piston. This consolidation eliminates the need for separate external actuator cylinders, reducing the overall device size and outer diameter requirement
2Area of stationary object
If the BOP outer diameter is reduced to use smaller surface vessels, then operational costs decrease, but the actuating force may be insufficient for sealing and shearing large diameter workover strings
Solution Approach 1:
The nested configuration allows the actuator piston to be received within the ram housing cavity, maximizing the use of available internal space. This arrangement enables a larger piston area to be accommodated within a compact envelope, generating sufficient actuating force while maintaining a reduced outer diameter suitable for smaller surface vessels
Solution Approach 2:
The patent changes the geometric parameters of the piston and cylinder arrangement by positioning the piston centrally within the ram housing and optimizing the piston area relative to the available space. This parameter optimization enables sufficient force generation within a compact envelope
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
Enables sealing and shearing of large diameter workover strings without the need for a correspondingly large outer diameter envelope, reducing operational costs by utilizing a more compact and efficient design.
Implementation Method 1
application of hydraulic pressure to the first and second piston chambers will move the cylinder ram from an open position in which the cylinder-ram is retracted from the BOP bore to a closed position in which the cylinder-ram extends across the BOP bore
Implementation Method 2
the hydraulic pressure which is used to actuate the cylinder-ram is conveyed from the first piston chamber to the second piston chamber. For example, the hydraulic pressure may be conveyed through a number of fluid passages which extend through the cylinder-ram
Data Source
Figure 1
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Figure 4
AI summary
A blowout preventer comprises a pair of ram assemblies which are mounted on diametrically opposite sides of a BOP housing. A cylinder-ram is slidably received within each ram assembly and includes a cylindrical cavity. A back plate couples with the outer end of the cylinder-ram and a piston head is positioned in the cavity, forming first and second piston chambers. Hydraulic pressure in the first and second piston chambers forces the cylinder ram from an open position to a closed position, thereby sealing the BOP bore.