Captured Ball Valve Mechanism for Through-Bore Frac Plug Sealing
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Solution Overview
Problem
Conventional caged ball directional flow valves are limited in newer plug designs, such as large bore frac plugs, where the setting tool passes through the center, preventing the use of caged balls due to tension loading issues and requiring thinner components, which hinders effective sealing and flow control during drilling operations.
Innovation Solution
A captured ball directional flow valve mechanism with a housing, ball, trunnion pins, and an elastomeric band that allows the setting tool to pass through and re-orient for sealing, using slots and boss ends to maintain the ball's position and allow one-directional flow, enabling automatic return to a sealing position upon tool detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional caged ball mechanism is used in a plug with a mandrel, then the ball can be constrained and sealed effectively, but the setting tool cannot pass through the center of the plug
Solution Approach 1:
The ball mechanism is segmented into a ball body with orthogonal through-bore and slot, mounted on trunnion pins that allow rotation. This segmentation enables the ball to be oriented differently - with the through-bore aligned with the plug's central axis to allow setting tool passage, or rotated 90 degrees to seal against the seat, thus resolving the contradiction between tool accessibility and sealing function
Solution Approach 2:
The ball is made dynamically reconfigurable through trunnion pin mounting, allowing it to rotate between operational positions. The ball can transition from a tool-access position (through-bore aligned with plug axis) to a sealing position (ball blocking the seat), providing adaptive functionality that resolves the static contradiction between tool passage and sealing requirements
2Reliability
If the ball is allowed to move freely for sealing, then flow control is achieved, but the ball cannot maintain proper position for setting tool attachment
Solution Approach 1:
The ball is pre-configured with a through-bore and slot oriented perpendicular to each other, with the through-bore initially aligned with the plug's central axis. This preliminary orientation allows the setting tool to attach to the far end of the plug before the plug is set, ensuring ease of operation while maintaining the capability for subsequent sealing action
3Strength
If a small diameter ball is used to fit within the mandrel, then the ball can be retained by a cage, but the plug cannot be designed with thinner components
Solution Approach 1:
The ball is extracted from the constraint of fitting within a central mandrel and is instead mounted on trunnion pins that extend from the plug's central axis. This extraction eliminates the need for a cage retention mechanism and allows the plug to be designed with thinner components, as the ball is positioned on the periphery rather than constrained within the central mandrel
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 efficient sealing and flow control in frac plugs by allowing the setting tool to pass through the center while ensuring the ball re-orientates for sealing, addressing the limitations of conventional designs and enhancing operational efficiency in drilling operations.
Implementation Method 1
an elastomeric band that allows the setting tool to pass through and re-orient for sealing
Data Source
AI summary
A flow control mechanism includes a housing defining a through bore and a cavity contiguous with the through bore, and a barrier received within the cavity of the housing. The barrier is moveable between a sealing position in which fluid flow through the housing is permitted in one direction through the housing and blocked in an opposite direction, and a non-sealing position in which the flow control mechanism is configured to receive an attachment member. An actuating mechanism returns the barrier to the sealing position when the attachment member separates. The actuating mechanism may be an elastomeric band that is in a non-stretched state when the barrier is in the sealing position and in a stretched state when the barrier is in the non-sealing position. The barrier returns from the non-sealing position to the sealing position by action of torque of the stretched flexible member as the flexible member returns to the non-stretched state.