Wellbore Control Device Self-Closing Gate Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional blowout preventers (BOPs) lack the ability to self-close in high internal pressure situations, relying on surface pressure or biasing devices that can fail or be ineffective, and are not fully pressure-balanced, leading to potential wellbore unsealing issues in subsea environments.
Innovation Solution
A wellbore control device with a gate mechanism where a first stem is attached to the gate and a second stem is releasably engageable, both exposed to internal and external pressures, allowing the gate to self-close when internal pressure exceeds external pressure, and re-engage when pressures balance, ensuring the wellbore remains sealed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional BOPs use surface pressure or biasing devices to close rams, then the wellbore can be sealed, but the system cannot self-close in high internal pressure situations and may fail when surface pressure fails
Solution Approach 1:
The patent converts the harmful effect of high internal pressure into a beneficial self-closing force. When internal pressure exceeds external pressure, the pressure differential acts on the stems to automatically drive the gate closed, transforming a dangerous condition into a safety mechanism that requires no external power or control systems.
Solution Approach 2:
The wellbore control device performs self-service by automatically closing when internal pressure exceeds external pressure. The pressure differential itself provides the actuating force, eliminating the need for external hydraulic systems, surface pressure, or complex control mechanisms to detect and respond to high pressure conditions.
2Ease of operation
If pressure-balanced configuration with dual stems is used, then the device is balanced at all times, but closure is still dependent on external closure force from surface or biasing devices
Solution Approach 1:
The patent transitions from a static pressure-balanced system to a dynamic one where the balance can be temporarily disrupted to enable automatic closure. When internal pressure exceeds external pressure, the dynamic pressure differential overrides the static balance and drives the gate closed, after which the system returns to its pressure-balanced state with the gate sealed.
3Strength
If biased rams are used to sever riser and tool string, then cutting capability is achieved, but the biasing devices are extremely heavy and may seize
Solution Approach 1:
The patent replaces heavy mechanical biasing devices with a pressure-differential-based actuation system. Instead of relying on massive springs or nitrogen accumulators, the gate is closed using the force generated by the pressure differential acting on the stems, eliminating the need for heavy biasing components while maintaining sufficient cutting force.
4Ease of operation
If rams extend out of BOP housing into surrounding water, then control is possible, but external pressure acts on ram ends to close rams when internal pressure is lower
Solution Approach 1:
The patent extracts the gate from the traditional ram configuration and replaces it with a gate mechanism that eliminates the problematic exposed ram ends. The gate design with stems that are partially exposed to both internal and external pressure removes the asymmetry that caused unintended closure, allowing the gate to respond only to pressure differentials rather than absolute external pressure.
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 device effectively self-closes the wellbore in high internal pressure scenarios, preventing unsealing and maintaining pressure balance, even when surface pressure or biasing systems fail, enhancing safety in subsea operations.
Implementation Method 1
when the internal pressure is greater than the external pressure, the pressure differential results in a force being applied to the gate to move the gate to, or retain the gate in, the throughbore closed position
Implementation Method 2
If the hydrostatic or external pressure on the seabed is greater than the pressure in the BOP (wellbore pressure), the external pressure will act on the ends of the rams to close the rams
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A wellbore control device for use in a blow out preventer is described. The control device comprising a housing defining a throughbore, a gate, the gate being movable between a throughbore open position and a throughbore closed position, a first stem attached to the gate and a second stem releasab!y engageable with the gate, the first and second stems being arranged such that a portion of each stem is exposed to an internal housing pressure and a portion of each stem is exposed to an external housing pressure. When the internal pressure is greater than the external pressure, the pressure differential results in a force being applied to the gate to move the gate to, or retain the gate in, the throughbore closed position.