Light Co-Solvent EOR Composition for Hard Water Reservoirs
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Solution Overview
Problem
Current Enhanced Oil Recovery (EOR) methods using chemical injection are costly and inefficient, particularly in hard water conditions where alkali injection can lead to precipitation of cations, requiring expensive chelants or water softening processes.
Innovation Solution
A non-surfactant aqueous composition comprising a light co-solvent, a water-soluble polymer, and an alkali agent is used to displace and convert unrefined petroleum acids into surfactants, reducing interfacial tension and viscosity, thereby enhancing oil recovery without the need for surfactants or expensive additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If alkali injection is used to react with organic acids in oil, then surfactant is generated in situ to lower interfacial tension and increase oil recovery, but cation precipitation occurs in hard water conditions requiring expensive chelants or water softening
Solution Approach 1:
A water-soluble polymer is introduced as an intermediary substance that complexes with cations (Ca2+, Mg2+) in hard water, preventing their precipitation when alkali is injected. This intermediary approach allows the beneficial alkali-oil acid reaction to proceed while the polymer mediates the harmful cation interactions, enabling cost-effective EOR in hard water reservoirs without requiring expensive chelants like EDTA
Solution Approach 2:
The invention changes the chemical parameters of the injection system by selecting specific water-soluble polymers with appropriate molecular weights and functional groups that can complex cations effectively. By adjusting polymer concentration and type, the system transforms hard water from a problematic condition into a manageable parameter, allowing alkali injection to proceed without cation precipitation issues
2Productivity
If expensive chelants like EDTA are added to prevent cation precipitation, then oil recovery is improved, but treatment cost increases significantly
Solution Approach 1:
The invention replaces expensive chelants like EDTA with cheaper water-soluble polymers that can be readily synthesized or obtained. These polymers serve as cost-effective alternatives that provide the necessary cation complexing function without the high cost associated with specialized chelating agents, making EOR treatment economically viable
Solution Approach 2:
Instead of using complex, expensive chelant molecules, the invention employs simpler water-soluble polymer structures that replicate the essential cation complexing function. These polymers copy the beneficial effect of chelants (preventing cation precipitation) while using more economical molecular structures that reduce treatment costs
3Productivity
If water softening processes are used to prevent cation precipitation, then oil recovery is improved, but treatment cost and process complexity increase
Solution Approach 1:
The invention extracts the problematic cations from the water phase by having them complex with the water-soluble polymer in the injection solution. This extraction approach eliminates the need for separate water softening process steps, simplifying the overall treatment system while still preventing cation precipitation in the reservoir
Solution Approach 2:
The water-soluble polymer provides self-service by automatically complexing with cations in the injection solution, preventing precipitation without requiring external water softening infrastructure or processes. This self-service mechanism simplifies the treatment system while maintaining effective oil recovery
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 composition is highly versatile and cost-effective, effective across a range of reservoir conditions, including high temperatures and high salinity, leading to increased oil recovery efficiency and reduced viscosity, making it suitable for heavy and viscous oils.
Implementation Method 1
The alkali reacts with the acid in the reactive oil to form soap in situ
Implementation Method 2
lower the interfacial tension enough to increase production
Implementation Method 3
Injection of a dilute solution of a water soluble polymer to increase the viscosity of the injected water
Implementation Method 4
thereby forming an emulsion in contact with the unrefined active petroleum material
Data Source
AI summary
Provided herein are inter alia non-surfactant aqueous compositions and methods having application in the field of enhanced oil recovery. In particular, non-surfactant compositions including light co-solvents and an alkali agent presented herein can be used, inter alia, for the recovery of a large range of crude oil compositions from challenging reservoirs.