Polyvinyl Alcohol Diverting Agent for Fracture Filling and Dissolution
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Solution Overview
Problem
Existing diverting agents used in hydraulic fracturing methods for shale layers do not dissolve in water and have slow biodegradation rates at low temperatures, leading to prolonged removal times, which hampers the efficient collection of natural gas and petroleum.
Innovation Solution
A diverting agent comprising a polyvinyl alcohol-based resin with a saponification degree of 90 mol % or more, which is partially dissolved in water, maintaining fracture filling for 30 minutes to 1 week and dissolving after a certain period, ensuring efficient removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If hydrolyzable resins such as polyglycolic acid or polylactic acid are used as diverting agents, then the fractures can be temporarily filled and the agents can disappear by hydrolysis, but the biodegradation rate is slow at low temperatures leading to prolonged removal times
Solution Approach 1:
The patent changes the chemical composition parameter from hydrolyzable resins (polyglycolic acid, polylactic acid) to polyvinyl alcohol-based resin with specific saponification degree (90 mol% or more). This parameter change enables the diverting agent to dissolve in water rather than requiring slow biodegradation, thus resolving the contradiction between maintaining temporary filling and reducing removal time.
2Loss of time
If polyvinyl alcohol-based resin with high saponification degree is used, then the agent dissolves in water for efficient removal, but the shape maintenance capability may be compromised
Solution Approach 1:
The patent specifies precise parameter ranges for the polyvinyl alcohol-based resin: saponification degree of 90 mol% or more, degree of polymerization of 100-1000, and specific dissolution rate (0.1-30 mass%). These parameter optimizations balance the competing requirements of water solubility for removal and shape maintenance during the fracturing process.
Solution Approach 2:
The diverting agent may comprise a composite system where polyvinyl alcohol-based resin is combined with other materials (such as inorganic particles or additional polymers) to enhance shape maintenance while preserving water solubility properties. This composite approach allows simultaneous achievement of shape stability and controlled dissolution.
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 polyvinyl alcohol-based resin diverting agent effectively fills fractures for a specified time, then dissolves in water, reducing environmental impact and enhancing the efficiency of resource collection by maintaining shape and dissolving as needed.
Implementation Method 1
a diverting agent which can maintain the shape for a certain period of time and disappears by hydrolysis when a natural gas, petroleum, or the like is collected
Data Source
AI summary
A problem to be solved of the present invention is to provide a diverting agent which gradually dissolves in water. The present invention relates to a diverting agent containing a polyvinyl alcohol-based resin and a method of filling a fracture using the diverting agent.