Polyvinyl Alcohol Plugging Agents Monovalent Salt Stabilization
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Solution Overview
Problem
Existing polyvinyl alcohol-based plugging agents are affected by acidic wellbore environments, leading to reduced solubility and performance issues in subterranean oil production operations, where high multivalent salt content can cause them to become unstable and difficult to remove.
Innovation Solution
Incorporating a specified amount of monovalent metallic salts into polyvinyl alcohol-based plugging agents, along with optional additives like plasticizers, starch, and fillers, to enhance their stability and solubility in acidic conditions, allowing for effective plugging and subsequent removal without permanent damage to productive sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyvinyl alcohol-based plugging agents are used in acidic wellbore environments with high multivalent salt content, then they provide effective plugging function, but their solubility decreases and they become unstable
Solution Approach 1:
Monovalent metallic salts act as intermediary substances that modify the chemical environment between the polyvinyl alcohol plugging agent and the acidic multivalent salt solution. These salts form a protective chemical environment that prevents direct adverse interactions between the plugging agent and harmful acidic conditions, thereby maintaining both plugging effectiveness and solubility stability.
Solution Approach 2:
The invention changes the chemical parameters of the plugging agent system by incorporating monovalent metallic salts. This modification alters the chemical composition and properties of the plugging agent, enabling it to maintain appropriate solubility and stability in acidic environments with high multivalent salt content while retaining its plugging functionality.
2Reliability
If polyvinyl alcohol-based plugging agents are used to plug high permeability regions, then they effectively divert drive fluid, but they become difficult to remove due to reduced solubility in acidic environments
Solution Approach 1:
Monovalent metallic salts serve as intermediary substances that maintain the solubility characteristics of polyvinyl alcohol in acidic environments. By creating a favorable chemical environment, these salts enable the plugging agent to be removed more easily after its diverting function is completed, reducing the difficulty of well remediation.
3Stability of the object's composition
If cements and solid slurries are used for physical plugging of high permeability regions, then they provide stable plugging, but they remain intact for extended periods requiring extraordinary efforts to reopen
Solution Approach 1:
The invention introduces dynamic characteristics to the plugging agent by using polyvinyl alcohol with controlled solubility. Unlike static cement plugs that remain permanent, this plugging agent can transition from a stable plugging state to a removable state. The monovalent metallic salts enable controlled dissolution over time, allowing the plug to be removed without extraordinary efforts, thus providing both stability during operation and ease of repair when needed.
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
The addition of monovalent metallic salts stabilizes polyvinyl alcohol-based plugging agents in acidic environments, ensuring effective temporary plugging and subsequent dissolution, thereby maintaining well productivity and reducing operational costs.
Implementation Method 1
polyvinyl alcohol with a certain amount of monovalent metallic salt, which is water-soluble and has a buffer effect even if the environment is acidic, and thus stable
Implementation Method 2
the diverting agent possess a property of controlled solubility wherein a satisfactory solid plug is formed for a period of time after which the plug is removed without further effort or treatment, for example, by being slowly dissolved
Data Source
AI summary
A particulate plugging agent, such as a diverting agent and/or loss circulation material, using a particular polyvinyl alcohol with a certain amount of monovalent metallic salt, which is water-soluble and has a buffer effect even if the environment is acidic, and thus stable, which in particular finds use in various subsurface oil production operations.