Graded Polymer Slug Flooding for Viscous Fingering Control
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Solution Overview
Problem
Conventional polymer flooding processes face challenges in achieving a favorable mobility ratio and sweep efficiency due to immiscible fingering and deformations, particularly when dealing with high viscosity hydrocarbons, leading to reduced hydrocarbon recovery and increased costs.
Innovation Solution
Implementing a graded polymer concentration profile in the polymer slug, with higher concentration at the front and lower concentration at the rear, and optionally heating the injection fluid to reduce hydrocarbon viscosity, to achieve a mobility ratio less than one and minimize deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant polymer concentration is used in polymer flooding, then the polymer solution can be easily injected and the process is simple to operate, but the mobility ratio becomes greater than one causing viscous fingering and reduced sweep efficiency
Solution Approach 1:
The patent applies local quality by creating a polymer slug with spatially varying polymer concentration. The front portion has higher polymer concentration to reduce mobility ratio and prevent viscous fingering, while the rear portion has lower concentration to maintain injectability and reduce polymer consumption. This non-uniform concentration distribution optimizes both sweep efficiency and operational feasibility.
Solution Approach 2:
The patent changes the polymer concentration parameter along the length of the polymer slug. By transitioning from a constant concentration to a graded concentration profile (higher at the front, lower at the rear), the system achieves better mobility control and reduced viscous fingering while maintaining practical injectability throughout the flooding process.
2Reliability
If the polymer concentration is increased to reduce mobility ratio and prevent viscous fingering, then sweep efficiency improves, but the amount of polymer required increases
Solution Approach 1:
The patent applies local quality by creating a polymer slug with spatially varying polymer concentration. The front portion has higher polymer concentration to reduce mobility ratio and prevent viscous fingering, while the rear portion has lower concentration to maintain injectability and reduce polymer consumption. This non-uniform concentration distribution optimizes both sweep efficiency and operational feasibility.
Solution Approach 2:
The patent changes the polymer concentration parameter along the length of the polymer slug. By transitioning from a constant concentration to a graded concentration profile (higher at the front, lower at the rear), the system achieves better mobility control and reduced viscous fingering while maintaining practical injectability throughout the flooding process.
3Reliability
If a high viscosity polymer solution is injected to control mobility ratio, then sweep efficiency increases, but the injection pressure and energy requirements increase
Solution Approach 1:
The patent applies local quality by creating a polymer slug with spatially varying polymer concentration. The front portion has higher polymer concentration to reduce mobility ratio and prevent viscous fingering, while the rear portion has lower concentration to maintain injectability and reduce polymer consumption. This non-uniform concentration distribution optimizes both sweep efficiency and operational feasibility.
Solution Approach 2:
The patent changes the polymer concentration parameter along the length of the polymer slug. By transitioning from a constant concentration to a graded concentration profile (higher at the front, lower at the rear), the system achieves better mobility control and reduced viscous fingering while maintaining practical injectability throughout the flooding process.
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 graded polymer concentration and heating method enhance sweep efficiency and hydrocarbon recovery while reducing polymer usage and avoiding immiscible fingering, thus optimizing the polymer flooding process.
Implementation Method 1
the polymer slug has a leading front and a trailing rear, and an S-shaped graded viscosity profile which decreases convexly in viscosity from the front of the polymer slug to an inflection point and concavely in viscosity from the inflection point to the rear of the polymer slug
Implementation Method 2
a mobility ratio (M) between the front of the polymer slug and hydrocarbons present in the subterranean reservoir is less than or equal to one
Implementation Method 3
injecting an aqueous solution from the injection well into the subterranean reservoir following (a) to displace the polymer slug through the subterranean reservoir
Implementation Method 4
heating a heating fluid by a surface heating system to a temperature that is greater than the temperature of at least some of the hydrocarbons present in the subterranean reservoir
Data Source
AI summary
A method for performing a polymer flood of a hydrocarbon-bearing, subterranean reservoir. The method includes injecting a polymer solution from an injection well (32) into the subterranean reservoir to form a polymer slug in the subterranean reservoir, wherein the polymer slug has a leading front and a trailing rear (48), and a graded viscosity profile which decreases in viscosity from the front of the polymer slug to the rear of the polymer slug. The method additionally includes injecting an aqueous solution (50) from the injection well into the subterranean reservoir following to displace the polymer slug through the subterranean reservoir.