Ball-and-seat isolation for multi-stage fracturing
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Solution Overview
Problem
Multi-stage fracturing processes face challenges with failures at isolation plugs, frac ports, and packers, which hinder effective stimulation of low-permeability rock formations for hydrocarbon production.
Innovation Solution
A method involving a cemented production liner with serially arranged frac seats that allow passage of a perforating gun, eliminating the need for packers by using balls to isolate zones and allowing sequential fracturing without bridge plugs or external packers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional multi-stage fracturing uses packers and bridge plugs to isolate zones, then zone isolation is achieved, but device complexity and failure risk increase
Solution Approach 1:
The patent removes packers and bridge plugs from the isolation system, extracting the problematic components that caused failures. Instead, it uses a simplified ball-and-seat mechanism where balls are dropped into the wellbore to seal against seats, eliminating the need for complex deployment and retrieval of traditional isolation devices.
Solution Approach 2:
The patent employs disposable balls as temporary isolation elements. These balls are inexpensive, easily deployed, and discarded after use by flowing them back to the surface. This replaces expensive, complex packers and bridge plugs that require careful deployment and retrieval, reducing both cost and failure risk.
2Reliability
If packers are used to isolate wellbore sections, then zone isolation is achieved, but operational cost and failure risk increase
Solution Approach 1:
The balls used as isolation elements are inexpensive compared to packers and bridge plugs. They can be easily manufactured and deployed without complex equipment, significantly reducing operational costs while maintaining effective zone isolation throughout the multi-stage fracturing process.
Solution Approach 2:
The ball isolation mechanism is self-deploying and self-removing. Balls are simply dropped into the wellbore where they automatically seal against the seats, and after use, they are flowed back to the surface without requiring additional intervention. This eliminates the need for expensive deployment and retrieval operations associated with traditional packers.
3Ease of operation
If frac ports are used for treatment fluid delivery, then fluid delivery is enabled, but failure points are created
Solution Approach 1:
The patent eliminates frac ports from the system entirely. Instead of having fixed ports that can fail, it uses the perforations themselves for treatment fluid delivery. The perforating gun creates holes through the casing and cement, providing direct pathways for fluid injection without requiring additional frac port components that could fail.
4Reliability
If isolation plugs are used to seal zones, then zone isolation is achieved, but failure risk and operational complexity increase
Solution Approach 1:
The patent removes isolation plugs from the system and replaces them with a simpler ball-and-seat mechanism. The balls are passive elements that seal against the seats through simple mechanical contact, eliminating the complex deployment, positioning, and sealing mechanisms required for traditional isolation plugs.
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 multi-stage fracturing by isolating wellbore sections without external packers or bridge plugs, reducing failures and operational costs, and enhancing hydrocarbon production through effective fluid flow and treatment fluid delivery.
Implementation Method 1
closing an opening in the seat to isolate the first section of the wellbore from a second section of the wellbore
Implementation Method 2
delivering treatment fluid from the production pipe to the wellbore through the access ports
Implementation Method 3
flowing formation fluid from the rock formation to the production pipe through the access ports
Data Source
AI summary
A method of fracturing a rock formation includes cementing a production pipe to a wellbore within the rock formation, wherein a seat is attached to an inner surface of the production pipe. The method further includes forming access ports along a first section of the wellbore that fluidly connect the production pipe to the wellbore, delivering treatment fluid from the production pipe to the wellbore through the access ports, flowing formation fluid from the rock formation to the production pipe through the access ports, and closing an opening in the seat to isolate the first section of the wellbore from a second section of the wellbore located above the first section.