Rupture Disc Plug for Uniform Fracture Treatment
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Solution Overview
Problem
Traditional fracture formation techniques, such as 'plug and perforate', fail to uniformly treat intervals with heterogeneous rock formations due to differential breakdown stress, where weaker formations receive more flow, leading to under-fracturing of stronger formations.
Innovation Solution
A plug design with an integral passage obstructed by a rupture disc that breaks at a predetermined high pressure, ensuring a spike in pressure to initiate fractures across all clusters, combined with a ball seat to isolate treated intervals and prevent swabbing, allowing uniform treatment across intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional pumping into the interval after perforating is used, then the process is simple and quick, but the treatment is non-uniform as weaker rock formations receive more flow and stronger formations are under-fractured
Solution Approach 1:
The rupture disc is pre-installed in the plug at a location above the perforated interval. Before treatment begins, the rupture disc breaks at a predetermined high pressure to open the passage, ensuring that the pressure spike is high enough to initiate fractures at every cluster in the stage interval before flow can preferentially enter weaker formations.
Solution Approach 2:
The rupture disc is designed to break at a predetermined high pressure that is high enough to fracture even the rock with the highest breakdown stress in the interval. This parameter change from normal operating pressure to high breakthrough pressure ensures uniform fracture initiation across all formations regardless of their individual breakdown stress levels.
2Manufacturing precision
If a rupture disc is used to build up high pressure, then uniform fracture initiation is achieved, but the device complexity and risk of premature activation increase
Solution Approach 1:
The rupture disc acts as an intermediary pressure-regulating element that mediates between the pumping system and the perforated interval. It allows pressure to build up to the required high level uniformly across all formations before allowing flow to proceed, preventing premature or non-uniform fracture initiation.
Solution Approach 2:
The rupture disc is positioned above the perforated interval and is designed to break only after pressure has built up to the predetermined high level. This preliminary positioning ensures that the pressure spike occurs before flow can preferentially enter weaker formations, guaranteeing uniform treatment.
3Reliability
If a ball seat is added to isolate treated intervals and prevent swabbing, then interval isolation reliability improves, but the plug complexity increases
Solution Approach 1:
The ball seat feature is extracted as a separate functional element from the main plug body. This modular approach allows the ball seat to be added to provide interval isolation and prevent swabbing without significantly complicating the overall plug design, as it is a simple receptacle that accepts a ball to seal the passage.
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 method ensures uniform fracture initiation across intervals with varying breakdown stress, preventing under-fracturing of stronger formations and ensuring effective stimulation by building pressure to a predetermined level before exposure to perforations.
Implementation Method 1
a rupture disc set to break at a predetermined high pressure that is high enough to fracture even the rock with the highest breakdown stress in the interval
Implementation Method 2
A ball is then dropped on a seat on the same plug and captured so that it will stay on the seat when a gun is removed above
Data Source
AI summary
A uniform interval treatment method features a plug with a breakable member in a passage set above a perforated interval so that pressure above the plug can be build up to the desired pressure that is high enough when the rupture disc breaks to deliver a burst of pressure at a level to overcome differential breakdown stress in the interval. A ball is then dropped on a seat on the same plug and captured so that it will stay on the seat when a gun is removed above. Another gun with a plug are delivered and the gun fired with the previous plug having a landed ball in the seat. The plug is again positioned above the just made perforations and the gun is removed. The rupture disc breaks to uniformly treat the next interval with a pressure to overcome differential breakdown stress of heterogeneous rock in the treated interval.