Reducing Agent Wettability Alteration for Oil Recovery
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Solution Overview
Problem
Current methods for enhancing oil recovery from hydrocarbon-bearing formations are limited by the oil-wet conditions of rock surfaces, which hinder oil mobility and recovery, particularly in fractured and carbonate formations.
Innovation Solution
The method involves altering the wettability of rock surfaces by injecting an aqueous stream containing reducing agents such as sodium carbonate, sodium nitrate, sodium bisulfite, or sodium sulfate, which change the surface charge to more water-wet conditions, thereby enhancing hydrocarbon recovery. This is achieved by selecting appropriate brine compositions and reducing agents that yield oxyanions, optimizing the concentration and interaction with the formation's characteristics through uncertainty analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If surfactant is used to enhance oil recovery, then oil mobility is improved, but surfactant retention on oil-wet surfaces increases
Solution Approach 1:
The patent applies preliminary action by injecting a reducing agent solution before the surfactant solution to alter the wettability of rock surfaces. The reducing agent converts oil-wet surfaces to water-wet surfaces in advance, creating favorable conditions for subsequent surfactant injection and reducing surfactant retention on rock surfaces.
Solution Approach 2:
The reducing agent acts as an intermediary substance that mediates between the oil-wet rock surfaces and the surfactant. It modifies the surface properties of the rock, enabling the surfactant to function more effectively with reduced retention and loss.
2Loss of substance
If reducing agent is injected to alter wettability, then surfactant retention is reduced, but injection complexity increases
Solution Approach 1:
The injection process is segmented into distinct stages: first injecting the reducing agent solution, then injecting the surfactant solution. This segmentation allows each chemical to perform its specific function optimally while simplifying the overall process control and monitoring.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the chemical composition of the injection solution (adding reducing agents like sodium bisulfite, sodium dithionite, or sodium sulfite) to fundamentally change the wettability parameter of the rock surfaces from oil-wet to water-wet, thereby improving subsequent surfactant performance.
3Ease of operation
If conventional water flooding is used, then injection simplicity is maintained, but oil mobility remains poor due to oil-wet conditions
Solution Approach 1:
The patent employs composite chemical treatment by combining reducing agents with surfactants in a sequential injection process. This composite approach creates a synergistic effect where the reducing agent modifies surface properties and the surfactant enhances oil mobility, achieving better results than conventional water flooding while maintaining operational simplicity.
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 approach effectively reduces surfactant retention and enhances oil recovery by converting oil-wet surfaces to water-wet conditions, improving oil mobility and recovery rates, as demonstrated by increased contact angle shifts and zeta potential changes, with reduced surfactant usage and improved imbibition processes.
Implementation Method 1
adding a reducing agent to the aqueous stream; and injecting the aqueous stream with the reducing agent into the formation to alter a surface charge of the surface of the formation
Implementation Method 2
The reducing agent when added to the aqueous stream yields a sufficient amount of oxyanions to change a surface charge to a more negative value to make the surface of the formation more water-wet
Implementation Method 3
Under fractured rock conditions, an imbibition process, a process by which injected brine is spontaneously sucked into the rock and ejects oil simultaneously, is the main mechanism of recovery of oil
Data Source
AI summary
Embodiments to enhance recovery of hydrocarbons from a formation by altering wettability at a surface of the formation towards more water-wet are provided. One embodiment comprises providing a formation, providing an aqueous stream for injecting into the formation, adding a reducing agent to the aqueous stream, and injecting the aqueous stream with the reducing agent into the formation to alter a surface charge of the surface of the formation to become more water-wet to enhance recovery of hydrocarbons from the formation. The reducing agent is responsive to characteristics of the formation, characteristics of brine of the formation, and characteristics of hydrocarbons of the formation. The embodiment also comprises injecting a second aqueous stream into the formation after injection of the aqueous stream with the reducing agent. The second aqueous stream comprises surfactant, mobility control agent, the reducing agent, or a combination thereof.