Acceleration-Triggered Ball Release Mechanism for Frac Plug Seating
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Solution Overview
Problem
Existing methods for delivering a ball to a seat in a frack plug during borehole fracturing operations are inefficient, particularly when perforating guns misfire, as they require costly and time-consuming alternative methods like coiled tubing or tractors, and existing ball release devices face issues with clearance, damage, and accuracy in horizontal wells.
Innovation Solution
A mechanical ball release mechanism using a spring-biased piston locked by an acceleration-responsive retainer, which utilizes the sudden movement caused by gun firing to propel the ball onto the frack plug seat, leveraging the potential energy stored in a main spring and opposed springs to ensure reliable and efficient delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the ball is delivered with the isolation device in the BHA, then the time to close the passage is reduced, but if the guns misfire, replacement guns cannot be delivered on wireline with pressure or flow assist
Solution Approach 1:
The ball delivery system is segmented into two independent paths: (1) a pre-positioned ball in the BHA for immediate seating, and (2) a separate ball release mechanism above the guns for alternative delivery. This segmentation allows the system to function in both scenarios - immediate closure when guns fire successfully, and alternative ball delivery when guns misfire and must be replaced.
Solution Approach 2:
The ball is pre-positioned within the BHA assembly before entering the wellbore, ready for immediate deployment upon gun firing. This preliminary positioning eliminates the need for time-consuming ball delivery operations under normal conditions, while the alternative release mechanism provides backup capability for misfire scenarios.
2Adaptability or versatility
If a ball release device is placed above the guns to release the ball into the annulus, then the ball can travel around the gun to the seat, but the ball may not fit in the annular space or be damaged by gun burrs
Solution Approach 1:
A dedicated ball release mechanism serves as an intermediary device positioned above the guns. This mechanism provides a controlled release path for the ball, protecting it from direct contact with gun burrs and sharp edges. The release mechanism includes guiding surfaces and protective features that ensure the ball remains intact during transfer from the release device to the frack plug seat.
Solution Approach 2:
The ball release mechanism creates a controlled pathway that replicates the ideal ball travel conditions without the harmful elements present in the annular space around the guns. By providing a dedicated release path, the system avoids the clearance limitations and damage risks associated with ball travel through the narrow annular space.
3Reliability
If the ball is pumped from the surface to the seat, then the passage can be closed, but it takes time and additional fluid displacement
Solution Approach 1:
The ball is pre-positioned within the BHA assembly before entering the wellbore, ready for immediate deployment upon gun firing. This preliminary positioning eliminates the need for time-consuming ball delivery operations under normal conditions, while the alternative release mechanism provides backup capability for misfire scenarios.
Solution Approach 2:
The ball release mechanism is self-actuating through the acceleration caused by gun firing. The inertial force generated during gun discharge automatically triggers the release mechanism, propelling the ball toward the frack plug seat without requiring external pumping operations or additional fluid displacement.
4Ease of operation
If the object is made small enough to travel past the gun in the annulus, then it can reach the seat, but the passage in the isolation device must be smaller causing delays and reduced flow rates
Solution Approach 1:
A dedicated ball release mechanism serves as an intermediary device positioned above the guns. This mechanism provides a controlled release path for the ball, protecting it from direct contact with gun burrs and sharp edges. The release mechanism includes guiding surfaces and protective features that ensure the ball remains intact during transfer from the release device to the frack plug seat.
Solution Approach 2:
Instead of constraining the ball to travel through the limited annular dimension around the guns, the release mechanism provides an alternative dimensional path - a dedicated release channel that bypasses the narrow annular space. This allows the ball to reach the seat without being sized according to the restrictive annular clearance, thereby maintaining full passage diameter and optimal flow rates.
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 enables rapid and reliable delivery of the ball to the frack plug seat, reducing operational costs and time delays, even in horizontal wells, by harnessing the relative movement from gun firing to initiate fracturing operations effectively.
Implementation Method 1
A mechanical ball release mechanism using a spring-biased piston locked by an acceleration-responsive retainer, which utilizes the sudden movement caused by gun firing to propel the ball onto the frack plug seat, leveraging the potential energy stored in a main spring
Implementation Method 2
The lock mechanism is a link that holds a potential force in the main spring. One end of the link is held by an acceleration or deceleration responsive retainer. Sudden relative movement caused by acceleration of the housing allows the retainer that is flanked by opposed springs to move away from the stop surface
Implementation Method 3
The retainer has a conforming stop surface to a stop surface on the link. Sudden relative movement caused by acceleration of the housing allows the retainer that is flanked by opposed springs to move away from the stop surface or surfaces on the link
Data Source
AI summary
A ball is retained behind a circular array of collet fingers to be pushed out through the collets with a spring biased piston that is initially locked when run in the hole. The lock mechanism is a link that holds a potential force in the main spring. One end of the link is held by an acceleration or deceleration responsive retainer. The retainer has a conforming stop surface to a stop surface on the link. Sudden relative movement caused by acceleration of the housing allows the retainer that is flanked by opposed springs to move away from the stop surface or surfaces on the link. The link is an array of spaced fingers that can radially flex. The radial flexing combines with the power of the main spring to propel the piston against the ball for a release of the ball. A fracturing operation then ensues.