Dissolvable Plugs for Multi-Zone Wellbore Acid Stimulation
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Solution Overview
Problem
In multi-zone wellbores, existing mechanical diversion plugs face challenges such as permanent sticking, high operational complexity, and increased costs due to the need for multiple electric line runs and potential rig mobilization for fishing operations, especially in large diameter wells, where reliable and cost-effective acid stimulation across multiple zones is hindered.
Innovation Solution
A method involving dissolvable plugs made from materials that react with acidic fluids, allowing for sequential and targeted acid injection into specific zones by dropping plugs that set and dissolve at controlled times, preventing fluid diversion into undesired zones, thereby ensuring effective acid treatment across multiple zones without the risk of permanent sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical diversion plugs are used in multi-zone wellbores, then fluid diversion into specific zones is achieved, but the risk of permanent sticking and mechanical failures increases
Solution Approach 1:
The patent changes the material parameter of the diversion plug from permanent mechanical materials to dissolvable materials that react with acidic fluids. The plug transitions from a permanent mechanical barrier to a temporary chemical barrier that dissolves after serving its purpose, eliminating the risk of permanent sticking while maintaining reliable fluid diversion during the stimulation process
Solution Approach 2:
The patent employs disposable dissolvable plugs made from materials like calcium carbonate or other acid-reactive substances that dissolve after a selected period of time. These temporary plugs serve their diversion function during acid injection and then naturally dissolve, eliminating the need for retrieval operations and avoiding mechanical failures associated with permanent plugs
2Ease of operation
If multiple electric line runs and rig mobilization are performed for fishing operations, then mechanical plugs can be retrieved or set, but operational complexity and costs increase
Solution Approach 1:
The patent replaces the mechanical retrieval system (electric line runs, wireline operations, rig mobilization) with a chemical dissolution system. Instead of mechanically retrieving the plug through complex operations, the plug is designed to chemically dissolve in the acidic stimulation fluid, automatically eliminating the need for mechanical retrieval infrastructure and operations
Solution Approach 2:
The dissolvable plug performs self-service by automatically dissolving in the acidic fluid after serving its diversion purpose. The plug eliminates itself without requiring external intervention, retrieval equipment, or additional operational steps, thereby simplifying the overall process and reducing costs
3Reliability
If dissolvable plugs made from acid-reactive materials are used, then fluid diversion is achieved without permanent sticking, but the plugs must be designed to dissolve at controlled times
Solution Approach 1:
The patent utilizes parameter changes in the form of controlled dissolution rates by selecting different acid-reactive materials or adjusting material properties. The plug material is engineered to dissolve at a controlled rate that matches the stimulation timeline, ensuring reliable fluid diversion during the critical period while automatically eliminating itself afterward
Solution Approach 2:
The patent employs composite material structures where the plug may consist of acid-reactive materials combined with other substances to achieve desired dissolution characteristics. This allows customization of the dissolution rate and pattern to match specific well stimulation requirements while maintaining ease of deployment
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 successful acid stimulation across all zones in a multi-zone wellbore at reduced costs, minimizing the risk of mechanical failures and allowing continuous pumping, thereby enhancing the efficiency and reliability of the acid treatment process.
Implementation Method 1
dissolvable plugs made from materials that react with acidic fluids, allowing for sequential and targeted acid injection into specific zones by dropping plugs that set and dissolve at controlled times
Data Source
AI summary
A method for stimulating a multi-zone wellbore completed with a string of production casing, including pumping a first volume of acidic fluid into the wellbore under pressure, and then injecting the first volume of acidic fluid into a first zone of interest along the production casing dropping at least one plug into the wellbore, the plug being fabricated from a material that substantially dissolves in the presence of the acidic fluid at or over a selected period of time.