Electro-Responsive Hydrogel Plugging for Targeted Thief Zone Control
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Solution Overview
Problem
Conventional hydrogels used for plugging water-thief zones in subterranean formations suffer from limited activation control and target location control, and are challenged by separation, shearing, and limited swelling capacity under downhole conditions.
Innovation Solution
Development of electro-responsive hydrogels formed from a polyelectrolyte mixture, activated by an electric current to swell, aggregate, or both, forming flow-diverting plugs to block pore throats and divert water flow into poorly swept zones, with reversible activation by reversing the electric current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional hydrogels are used for plugging water-thief zones, then the formation can be sealed to some extent, but the activation control and target location control are limited
Solution Approach 1:
The patent replaces conventional mechanical or chemical activation mechanisms with an electro-responsive system. The hydrogel particles are designed to respond to electric fields, allowing precise spatial and temporal control of activation. By applying electric current through injection wells, the hydrogel swells only in targeted zones where the electric field is applied, achieving superior target location control and activation precision without complex mechanical delivery systems.
2Reliability
If conventional hydrogels are injected into subterranean formations, then they can plug water flow paths, but they suffer from separation, shearing, and limited swelling capacity under downhole conditions
Solution Approach 1:
The patent employs composite hydrogel particles combining conductive polymers (such as polyaniline, polythiophene, or polypyrrole) with hydrogel matrices (such as polyacrylamide, polyacrylic acid, or cellulose derivatives). This composite structure provides both the swelling capability of hydrogels and the structural integrity of conductive polymers, enabling the particles to maintain their integrity under downhole conditions while achieving significant swelling capacity when activated by electric fields.
Solution Approach 2:
The patent utilizes electric field parameters (voltage, current density, pulse duration) to control hydrogel activation. By adjusting these parameters, the hydrogel can be activated to swell to specific degrees, achieving optimal plugging capacity while minimizing adverse effects. The electric field-induced swelling is reversible and controllable, allowing the hydrogel to adapt to varying downhole conditions without suffering from permanent damage due to separation or shearing.
3Productivity
If hydrogels are used to improve sweep efficiency, then water flow can be diverted into poorly swept zones, but the process is dependent on temperature or salinity changes
Solution Approach 1:
The patent replaces temperature- or salinity-dependent activation mechanisms with electro-responsive activation. Conventional hydrogels require changes in temperature or ionic strength to trigger swelling, but the electro-responsive hydrogel uses electric field stimulation instead. This substitution allows activation to be controlled independently of downhole temperature and salinity conditions, providing versatile and reliable sweep efficiency improvement across diverse reservoir environments.
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
Enhances hydrocarbon recovery by improving sweep efficiency and mobility control, allowing targeted plugging of thief zones and redistribution of pore pressure gradients, independent of temperature or salinity changes.
Implementation Method 1
an electric current is applied through the electric circuit, thereby exposing the electro-responsive hydrogel particles to an electric field and causing at least one of swelling or aggregation of the electro-responsive hydrogel particles to form a flow-diverting plug
Implementation Method 2
an electric current is applied through the electric circuit, thereby exposing the electro-responsive hydrogel particles to an electric field
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
Electro-responsive hydrogel particles are flowed into a first wellbore formed in a subterranean formation. An electric circuit is established between the first wellbore and a second wellbore formed in the subterranean formation. An electric current is applied through the electric circuit, thereby exposing the electro-responsive hydrogel particles to an electric field and causing at least one of swelling or aggregation of the electro-responsive hydrogel particles to form a flow-diverting plug within the subterranean formation. Water is flowed into the first wellbore to increase hydrocarbon production from the second wellbore.