Reducing Agent Brine Wettability Alteration
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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 the mobility of oil and result in poor recovery due to the adhesion of oil to the rock, especially in carbonate formations.
Innovation Solution
The method involves altering the wettability of the rock surface by injecting an aqueous stream containing a reducing agent, such as sodium carbonate, sodium nitrate, or sodium bisulfite, to change the surface charge from positive to negative, making the surface more water-wet, thereby enhancing oil recovery. This is achieved by selecting appropriate brine compositions and reducing agents that yield oxyanions, which are optimized using uncertainty analysis to improve oil flow and recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rock surface maintains oil-wet conditions, then oil adheres to the rock surface, but oil mobility is reduced and recovery is poor
Solution Approach 1:
The patent applies parameter changes by modifying the surface charge density of rock minerals through chemical treatment. Specifically, it uses reducing agents to change the zeta potential from positive to negative values, which fundamentally alters the wettability characteristics of the rock surface. This parameter change in surface charge enables the transition from oil-wet to water-wet conditions, thereby improving both oil mobility and recovery
2Productivity
If a reducing agent is added to aqueous stream, then surface charge changes to negative and wettability improves, but injection process complexity increases
Solution Approach 1:
The patent employs preliminary action by pre-selecting and pre-mixing appropriate reducing agents with the aqueous injection stream before injection. The reducing agents are chosen based on their ability to effectively change surface charge in the specific formation conditions. This preliminary preparation ensures that the chemical treatment is ready to act immediately upon contact with the rock surface, simplifying the overall injection process while maintaining effectiveness
Solution Approach 2:
The patent uses reducing agents as intermediaries to mediate between the aqueous injection stream and the rock surface. These chemical intermediaries (such as sodium bisulfite, sodium metabisulfite, or other reducing compounds) facilitate the charge reversal process by donating electrons to the rock surface, enabling wettability modification without requiring direct complex mechanical or physical intervention
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 the retention of oil on rock surfaces, increasing oil mobility and recovery rates by converting oil-wet conditions to water-wet, as demonstrated by improved contact angles and zeta potential measurements, leading to enhanced oil recovery with reduced surfactant usage.
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
altering wettability at a surface of the formation towards more water-wet... By changing the rock character to be more water-wet, oil will flow more freely rather than being bound to the rock surface
Data Source
AI summary
Embodiments herein select a brine composition to be injected into a formation to alter wettability at a surface of the formation to enhance recovery of hydrocarbons from the formation. One embodiment comprises providing: a plurality of substrates representative of a formation, a plurality of brine compositions, and a plurality of reducing agents characterized as yielding oxyanions when added to an aqueous stream. The embodiment comprises selecting a brine composition with at least one reducing agent to be injected into the formation to alter wettability at a surface of the formation to enhance recovery of hydrocarbons from the formation and injecting the selected brine composition into the formation to alter wettability at the surface of the formation to enhance recovery of the hydrocarbons from the formation. The brine composition is selected based on interactions between the plurality of substrates, the plurality of brine compositions, and the plurality of reducing agents.