Low-Density Hydrogel Tip Screen-Out for Hydraulic Fracture Control
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Solution Overview
Problem
Current methods for manipulating hydraulic fracture geometry in rock matrices are limited in their ability to selectively control fracture propagation, which is essential for optimizing energy storage and power generation in geomechanical pumped storage systems or improving mineral resource production.
Innovation Solution
The method involves injecting a fracturing fluid to generate hydraulic fractures, draining fluids, and then using hydrophilic polymers and crosslinking agents to form low-density hydrogels or pre-formed particle gels that selectively screen out the tips of the fractures, allowing the fracture width to increase without extending the fracture length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid materials are used to fill and bridge the hydraulic fracture to stop fluid flow, then fracture propagation is arrested, but the bulk of the fracture cannot remain open for energy storage or mineral production
Solution Approach 1:
The patent changes the physical state and density parameters of the plugging material by using hydrophilic polymers that form low-density hydrogels upon contact with formation water. This allows the material to effectively screen out the fracture tip while occupying minimal volume, thereby plugging the fracture without filling the bulk fracture space needed for energy storage or mineral production.
Solution Approach 2:
The patent applies local quality by concentrating the plugging action specifically at the fracture tip region rather than throughout the entire fracture. The low-density hydrogel material is injected and accumulates preferentially at the tip where formation water first contacts it, creating a localized screen-out that stops propagation while leaving the rest of the fracture open.
2Length of moving object
If fracture length is extended for greater storage capacity, then energy storage potential increases, but fracture width must be maintained to ensure hydraulic performance
Solution Approach 1:
The patent applies preliminary action by injecting the low-density hydrogel material before the working fluid is injected for energy storage operations. This pre-plugging of the fracture tip creates a screen-out that prevents further propagation during subsequent working fluid injection, allowing the fracture to be extended to desired lengths without concern for uncontrolled width increases from continued propagation.
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 effectively increases the apparent fracture toughness, arrests further fracture growth, and enhances the hydraulic performance of the fractures, leading to improved energy storage, power generation, and mineral resource production capabilities.
Implementation Method 1
injecting a hydrophilic polymer and one or more crosslinking agents into the well to subsequently form low-density hydrogels
Implementation Method 2
injecting a hydrophilic polymer and one or more crosslinking agents into the well to subsequently form low-density hydrogels
Implementation Method 3
injecting a working fluid into the well to increase fracture width of the one or more hydraulic fractures
Data Source
AI summary
Materials for manipulating hydraulic fracture geometry. In one embodiment, the materials comprises a tip screen-out mixture, which comprises water; a hydrophilic polymer of anionic polyacrylamide, wherein the hydrophilic polymer is hydrolized at least in part; and one or more crosslinking agents selected from a group of compounds consisting of polyvalent metal cations.