Viscoelastic Fluid Stability in Saline Environments
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Viscoelastic compositions used in enhanced oil recovery methods face instability at high ionic strengths and temperatures, leading to loss of viscosifying power, especially in saline environments and elevated temperatures.
Innovation Solution
A viscoelastic aqueous fluid comprising a viscosifying zwitterionic surfactant and an alkaline compound is injected into underground formations, maintaining viscosity and reducing interfacial tension by adjusting the pH to greater than 10, thereby enhancing oil recovery and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If zwitterionic surfactants are used to maintain stability in brines, then stability in saline environments is improved, but decomposition occurs at temperatures greater than 80/100°C
Solution Approach 1:
The patent changes the chemical parameters of the surfactant system by combining zwitterionic surfactants with specific additives and adjusting concentrations to achieve stability at high temperatures while maintaining brine compatibility. This resolves the contradiction by modifying the chemical composition parameters rather than using a single surfactant type.
Solution Approach 2:
The invention uses composite surfactant systems combining zwitterionic surfactants with other surfactant types and additives to achieve both brine stability and temperature resistance. The composite formulation allows each component to contribute its strengths, resolving the contradiction between saline stability and thermal stability.
2Force
If viscosifying agents are used to increase drive fluid viscosity, then oil flushing is improved, but stability is inadequate in the presence of divalent ions
Solution Approach 1:
The patent introduces specific additives as intermediaries that protect the viscosifying agents from degradation by divalent ions. These additives act as mediators between the viscosifier and the saline environment, preventing harmful interactions while maintaining viscosity enhancement.
Solution Approach 2:
The invention modifies the chemical parameters of the viscosifying system by selecting specific polymer types and concentrations that are resistant to divalent ion degradation, while also adjusting pH and adding protective additives to maintain stability in the presence of calcium and magnesium ions.
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 solution maintains viscosity and reduces interfacial tension effectively at high temperatures and saline conditions, allowing for improved oil recovery without the need for oxygen scavengers, ensuring chemical stability and viscosifying power.
Implementation Method 1
These water-dispersible and/or water-soluble surfactants, on contact with the oil present in the rock or the sand, lower the water/oil interfacial tension to make possible the entrainment of the oil trapped in the constrictions of the pores of the reservoir.
Implementation Method 2
These polymers are used to increase the viscosity of the drive fluid and to thus improve the flushing of the oil by the drive fluid.
Implementation Method 3
A viscoelastic aqueous fluid comprising a viscosifying zwitterionic surfactant and an alkaline compound is injected into underground formations, maintaining viscosity and reducing interfacial tension by adjusting the pH to greater than 10
Data Source
AI summary
The present invention relates to a method for the enhanced recovery of oil from an underground formation, in which a viscoelastic aqueous fluid comprising at least one viscosifying zwitterionic surfactant is injected into the said formation and the said fluid is conducted through this formation in order to displace the oil from the formation and to recover it via a different point from that where the viscoelastic aqueous fluid was introduced, characterized in that the said fluid exhibits an amount of a base sufficient to bring its pH to a value of greater than 10, preferably of between approximately 11 and 13.