Blowout Preventer Pressure-Isolated Piston Assembly
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Solution Overview
Problem
Existing wellhead assembly systems face inefficiencies due to retraction forces applied to connecting rods by wellbore pressure when rams are closed, which can lead to reduced sealing effectiveness and increased fatigue, particularly at higher pressure ratings.
Innovation Solution
Incorporating pressure-isolating seals between connecting rods and rams, and providing relief paths for fluid escape within recesses, to isolate the operating piston assembly from wellbore pressure, thereby reducing retraction forces and enhancing sealing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If connecting rods are directly exposed to wellbore pressure when rams are closed, then the system can operate at higher pressures, but retraction forces are applied to the connecting rods that reduce sealing effectiveness and increase fatigue
Solution Approach 1:
The patent segments the pressure environment by creating a pressure-isolated region for the connecting rod end face within the ram, separated from the wellbore pressure region by a seal. This allows the connecting rod to be protected from wellbore pressure while the ram operates under high pressure, eliminating retraction forces on the connecting rod that would otherwise reduce sealing effectiveness and increase fatigue.
Solution Approach 2:
The patent introduces a seal as an intermediary element between the connecting rod end face and the wellbore pressure environment. This seal acts as a barrier that mediates the pressure interaction, allowing the connecting rod to remain in a pressure-isolated region while the ram operates under wellbore pressure, thereby eliminating harmful retraction forces.
2Duration of action of stationary object
If connecting rods are exposed to wellbore pressure, then the system structure can be simpler, but sealing fatigue life is reduced due to the wellbore assist effect on ram assemblies
Solution Approach 1:
The patent divides the ram assembly into pressure-isolated and pressure-exposed regions, with the connecting rod end face located in the pressure-isolated region. This segmentation protects the connecting rod and seal interface from wellbore pressure cycling, thereby extending sealing fatigue life while maintaining a relatively simple overall structure through the use of integrated relief paths.
Solution Approach 2:
The patent changes the pressure parameter experienced by the connecting rod end face from high wellbore pressure to near-zero pressure by creating a pressure-isolated region. This parameter change eliminates the wellbore assist effect that would otherwise reduce sealing fatigue life, while the relief paths ensure the isolation structure remains simple and integrated.
3Productivity
If pressure-isolating seals are added to isolate the operating piston assembly, then retraction forces are reduced and sealing efficiency increases, but device complexity increases
Solution Approach 1:
The patent merges the pressure isolation function with the existing ram and connecting rod structure by integrating relief paths directly into these components. This combining approach creates the pressure-isolated region using minimal additional structure, reducing the complexity increase that would otherwise result from adding separate isolation mechanisms while still achieving the efficiency gains from eliminating retraction forces.
Solution Approach 2:
The patent implements self-service by allowing the relief paths to automatically equalize pressure within the pressure-isolated region without requiring external control systems. The relief paths passively vent pressure when needed, eliminating the need for complex active pressure management systems while maintaining the efficiency benefits of pressure isolation.
4Ease of manufacture
If the connecting rod is received laterally in a slot open to both end face and side of the ram, then assembly is easier, but wellbore pressure acts on the connecting rod causing retraction forces
Solution Approach 1:
The patent inverts the traditional lateral slot reception approach by having the connecting rod received in a recess in the end face of the ram rather than laterally in a slot. This inversion, combined with pressure isolation, prevents wellbore pressure from acting on the connecting rod end face, thereby eliminating retraction forces while the recess design maintains ease of assembly through straightforward axial insertion.
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 increases system efficiency, extends sealing fatigue life, and allows for operation at higher pressures or reduced system size while maintaining maximum pressure handling capabilities.
Implementation Method 1
seals between the connecting rods and the rams that isolate end faces of the connecting rods from wellbore pressure within the blowout preventer
Implementation Method 2
relief paths that allow fluid within pressure-isolated regions in recesses of the rams to escape
Data Source
AI summary
A ram-type blowout preventer including an operating piston assembly isolated from wellbore pressure effects is provided. In one embodiment, a blowout preventer includes piston coupled to a ram by a connecting rod, and the connecting rod is inserted into a recess in the ram. A pressure-isolating seal may be provided in the recess between the connecting rod and the ram to isolate the end of the connecting rod within the recess from wellbore pressure in the blowout preventer. Additional systems, devices, and methods are also disclosed.