Expandable Ball Seat for Single-Frac-Ball Multi-Zone Stimulation
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Solution Overview
Problem
Conventional wellbores using frac sleeves require multiple frac-balls of different sizes to activate each sleeve sequentially, limiting the number of fracturing stages and frac rate due to pressure drops and accumulation of sand, making it inefficient to treat geological formations and impossible to create additional fractures without mechanical intervention.
Innovation Solution
A frac sleeve with an expandable ball seat that allows a single frac-ball to treat multiple zones by using a vertically adjustable member and variable port, enabling pressure-controlled alignment and expansion to facilitate fluid flow and sand removal, allowing seamless operation across an infinite number of sleeves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple frac-balls of different sizes are used to activate each frac sleeve sequentially, then each sleeve can be activated in order, but the number of fracturing stages is limited and pressure drops occur
Solution Approach 1:
A single frac-ball is designed to activate multiple frac sleeves at different depths by collapsing variable diameter ball seats within each sleeve. The ball seat expands to different diameters at different vertical positions, allowing one ball to sequentially trigger multiple stages without requiring multiple balls of different sizes.
Solution Approach 2:
The ball seat incorporates a vertically adjustable member with variable diameter that can dynamically expand and collapse in response to pressure changes. When pressure increases, the ball seat collapses to a smaller diameter to allow the frac-ball to pass through; when pressure decreases, it expands to a larger diameter to block the sleeve and activate fracturing.
2Ease of operation
If conventional frac sleeves with tapered sidewalls are used, then activation is achieved with properly sized frac-balls, but sand accumulates in the wellbore after fracking stages
Solution Approach 1:
Instead of allowing sand to accumulate in the wellbore as in conventional systems, the invention inverts the flow direction by enabling fracturing to occur from the uppermost frac sleeve downward. The single frac-ball travels from top to bottom, activating sleeves in reverse sequence, which prevents sand accumulation in the wellbore by maintaining continuous fluid flow in the same direction.
3Productivity
If tapered frac sleeves are used with different sized frac-balls, then each sleeve can be activated, but the frac rate is limited due to huge pressure drop across smallest ball seats
Solution Approach 1:
The ball seat diameter is changed dynamically based on the operational phase. During activation, the ball seat collapses to a small diameter to allow the frac-ball to pass through. During fracturing, it expands to a large diameter to block the sleeve and build pressure. This parameter change eliminates the continuous pressure drop inherent in tapered sleeves with fixed small openings.
4Adaptability or versatility
If conventional completion strings are used, then multiple fractures can be created, but additional fractures cannot be created without mechanical intervention
Solution Approach 1:
The frac sleeve system is designed to be self-activating through pressure control alone. The vertically adjustable member automatically expands and collapses in response to pressure changes, requiring no mechanical intervention for re-fracturing. After initial activation, the same sleeve can be activated again by simply injecting another frac-ball, allowing multiple fractures to be created without complex mechanical systems.
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 fracking from the uppermost to the lowest frac sleeve, reducing sand accumulation, increasing the number of fractures, and eliminating the need for multiple ball sizes, thus enhancing the treatment of geological formations and reducing operational time.
Implementation Method 1
When the frac-ball is positioned on the expandable ball seat, pressure may be applied within the frac sleeve to compress the vertically adjustable member
Implementation Method 2
When the expandable ball seat is aligned with the ring locking mechanism, the expandable ball seat may expand horizontally into the ring locking mechanism
Implementation Method 3
as the pressure within the frac sleeve is decreased, the vertically adjustable member may expand
Data Source
AI summary
A frac sleeve includes an expandable ball seat configured to allow a single frac-ball to treat a plurality of zones associated with a plurality of frac sleeves.