Sliding Sleeve Sub Ball Stop Mechanism for Wellbore Zone Access
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Solution Overview
Problem
Existing wellbore treatment systems are limited in the number of zones that can be accessed due to size constraints, specifically the inner diameter of wellbore tubulars, which restricts the number of sleeves that can be installed and thus limits the number of stages that can be treated.
Innovation Solution
A sliding sleeve sub with a configurable ball stop mechanism that allows for the formation of a valve seat downhole, enabling the use of a single-sized ball or plug to actuate multiple sleeves, thereby increasing the number of stages that can be treated without reducing the inner diameter of the tubular string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the inner diameter of wellbore tubulars is reduced to accommodate more sleeves, then the number of treatable zones increases, but the inner diameter available for treatment tools decreases
Solution Approach 1:
The ball stop is configured in a movable manner within the sleeve, transitioning from a retracted position (allowing ball passage) to an extended position (blocking ball passage). This dynamic configuration allows the same sleeve structure to serve multiple functions: maintaining open inner diameter during tool passage and creating ball retention points when needed, thereby increasing the number of treatable zones without reducing tubular inner diameter.
Solution Approach 2:
The system changes the effective inner diameter parameter dynamically. When the ball stop is retracted, the full inner diameter is available for treatment tools. When the ball stop is extended to create a ball retention point, the effective inner diameter is reduced locally to retain the ball. This parameter change enables multiple sleeves to be actuated by balls of the same size while maintaining adequate clearance for treatment tools.
2Adaptability or versatility
If multiple ball sizes are used to actuate different sleeves, then each sleeve can be selectively opened, but the complexity of the actuation system increases
Solution Approach 1:
The ball stop mechanism is designed to create ball retention points of different effective diameters using the same basic structure and the same sized balls. By varying the extension position of the ball stop, different retention diameters are created, allowing selective actuation of different sleeves with a single ball size. This universal mechanism eliminates the need for multiple ball sizes while maintaining selective zone access capability.
Solution Approach 2:
The ball stop is divided into multiple segments or positions along its travel path, with each position corresponding to a specific sleeve's activation point. As the ball travels through the tubular, it interacts with different segments of the ball stop mechanism at different locations, triggering sequential sleeve openings. This segmentation allows a single ball to actuate multiple sleeves in sequence without requiring different ball sizes.
3Quantity of substance
If the number of sleeves is increased to treat more zones, then more zones can be accessed, but the inner diameter constraints prevent adding more sleeves
Solution Approach 1:
The ball stop's dynamic reconfiguration capability allows the system to maintain a large open inner diameter for most of the tubular length while creating localized ball retention points only when needed. This enables packing more sleeves into the available space without permanently reducing the inner diameter, thereby increasing the number of treatable zones within the same tubular size constraints.
Solution Approach 2:
The ball stop mechanism is nested within the sleeve structure, with the ball stop extending into the inner bore only when needed to create a retention point. When retracted, the ball stop is nested within the sleeve wall, maintaining the full inner diameter. This nested arrangement allows multiple such mechanisms to be packed into the tubular string without excessive space consumption, enabling more treatable zones within diameter constraints.
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 allows for the treatment of a greater number of stages within the wellbore by enabling the configuration of valve seats on the sleeves, allowing for staged fluid injection into selected intervals while maintaining a substantial open inner diameter, thus overcoming the size limitations of traditional systems.
Implementation Method 1
conveying an actuating device to actuate the first sleeve and generate thereon a ball stop
Implementation Method 2
increasing fluid pressure in the tubing string above the sleeve shifting ball to move the first sleeve to open a port
Data Source
AI summary
A tubing string assembly is disclosed for fluid treatment of a wellbore. The tubing string can be used for staged wellbore fluid treatment where a selected segment of the wellbore is treated, while other segments are sealed off. The tubing string can also be used where a ported tubing string is required to be run in in a pressure tight condition and later is needed to be in an open-port condition.