Dissolvable Plugs for Multi-Zone Well Stimulation
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Solution Overview
Problem
Current methods for stimulating multi-zone wells face challenges such as limited effectiveness of chemical diverters and mechanical plugs, including risk of mechanical failure, high costs, and complexity, especially in deviated wells, where ensuring uniform acid distribution and avoiding plug sticking are significant issues.
Innovation Solution
A pre-perforated tubular body with dissolvable plugs is used, where each set of plugs is designed to dissolve at specific times in response to acidic stimulation fluids, allowing for controlled acid injection and zone isolation without the need for wireline operations, thereby optimizing acid circulation and reducing the risk of mechanical failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical plugs are used to isolate zones for acid stimulation, then zone isolation reliability is improved, but device complexity and risk of mechanical failure increase
Solution Approach 1:
The patent replaces mechanical plugs with a chemical system using viscous diverters (foams or gels) to isolate zones for acid stimulation. The viscous diverter is injected into the formation and sets to create a barrier, eliminating the need for mechanical plug deployment equipment and reducing mechanical failure risks while maintaining zone isolation reliability.
Solution Approach 2:
The patent introduces a viscous diverter as an intermediary substance between the acid stimulation fluid and the formation. This diverter temporarily blocks certain zones, allowing selective acid injection into target zones without requiring mechanical plugs. The diverter acts as a temporary mediator that can be deployed and removed without complex mechanical operations.
2Device complexity
If chemical diverters are used for acid stimulation, then device complexity is reduced, but effectiveness in ensuring uniform acid distribution deteriorates
Solution Approach 1:
The patent modifies the parameters of chemical diverters by using viscous fluids (foams or gels) with controlled viscosity and setting characteristics. The viscous diverter is designed to set rapidly upon injection, creating an effective barrier that ensures uniform acid distribution into the formation. The viscosity and setting time are optimized to prevent acid bypass while allowing complete penetration into target zones.
3Reliability
If mechanical plugs are used in deviated wells, then zone isolation is improved, but risk of plug sticking increases
Solution Approach 1:
The patent replaces mechanical plugs with viscous chemical diverters in deviated wells. The viscous diverter is pumped through the wellbore and sets in place to isolate zones, eliminating the risk of plug sticking to the wellbore wall. The chemical setting mechanism provides reliable zone isolation without the mechanical adhesion problems that occur with traditional plugs in deviated orientations.
4Manufacturing precision
If wireline operations are used for plug deployment, then precise zone isolation is achieved, but operational complexity and time requirements increase
Solution Approach 1:
The patent employs a viscous diverter system that can be deployed through standard wellbore operations without requiring wireline equipment. The diverter is pumped down the wellbore and automatically sets in place to isolate zones, eliminating the need for complex wireline deployment operations while maintaining precise zone isolation. The system serves itself by using the pumping operation to both deliver and deploy the isolation mechanism.
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 approach ensures reliable and efficient acid distribution across multiple zones, reducing the risk of plug sticking and operational complexity, while maintaining the benefits of mechanical plugs in terms of reliability and avoiding the limitations of chemical diverters, thus enhancing the stimulation process in both vertical and deviated wells.
Implementation Method 1
each set of plugs is designed to dissolve at specific times in response to acidic stimulation fluids
Implementation Method 2
The acid helps to dissolve carbonate material, thereby opening up porous channels through which hydrocarbon fluids may flow into the wellbore
Data Source
AI summary
A system for stimulating a multi-zone well includes a tubular body apportioned into at least a first zone and a second zone. The system has a first set of plugs placed in pre-drilled holes along the tubular body within the first zone. The plugs in the first set of plugs are fabricated to substantially dissolve upon contact with an acidic stimulation fluid within a first selected time. The system also has a second set of plugs placed in pre-drilled holes along the tubular body within the second zone. The plugs in the second set of plugs are fabricated to substantially dissolve upon contact with the acidic fluid within a second selected time that is greater than the first selected time.