Anionic Dimer Surfactant Compositions for Tight Shale Recovery
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Solution Overview
Problem
Conventional surfactants used in hydraulic fracturing for oil recovery are unstable and adsorb strongly to rock surfaces in high temperature and high total dissolved solids environments, leading to reduced hydrocarbon recovery and emulsion formation.
Innovation Solution
Compositions comprising anionic dimer surfactants, anionic monomer surfactants, a demulsifier, and a coupling agent, which are thermally stable and exhibit low adsorption to rock surfaces, preventing emulsion formation and increasing hydrocarbon recovery in tight shale reservoirs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional surfactants are used to lower interfacial tension and change wettability, then hydrocarbon recovery is improved, but surfactant stability deteriorates in high temperature and high salinity environments
Solution Approach 1:
The patent changes the chemical parameters of the surfactant by using specific molecular structures (sulfonated isomerized fatty acids with particular chain lengths and degrees of isomerization) that are inherently more stable at high temperatures and salinities while maintaining their surfactant properties. This resolves the contradiction by finding a surfactant composition that satisfies both stability and effectiveness requirements.
Solution Approach 2:
The patent employs composite surfactant systems combining multiple components (sulfonated isomerized fatty acids with specific ratios of different chain lengths, combined with alkali metal salts) to achieve both thermal/salinity stability and effective hydrocarbon recovery. The composite nature allows the system to benefit from the synergistic effects of different molecular components.
2Productivity
If conventional surfactants are used to alter rock wettability, then oil release from rock surfaces is improved, but surfactant adsorption onto rock surfaces increases, depleting surfactant quickly
Solution Approach 1:
The patent modifies the adsorption parameters by changing the surfactant molecular structure to sulfonated isomerized fatty acids with specific hydrophobic chain characteristics. These structural changes reduce the affinity for rock surfaces while maintaining the ability to alter wettability and release oil, thereby reducing surfactant depletion.
3Productivity
If conventional surfactants are used to enhance hydrocarbon recovery, then oil yield is improved, but emulsion formation between hydrocarbon compounds and fracturing fluid increases
Solution Approach 1:
The patent changes the surfactant parameters by selecting specific sulfonated isomerized fatty acid structures that have reduced emulsifying properties compared to conventional surfactants. The specific chain lengths, degrees of isomerization, and sulfonation patterns create a surfactant that effectively releases oil from rock but does not stabilize water-oil emulsions, thus resolving the contradiction between oil recovery and emulsion prevention.
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 compositions effectively alter rock wettability from oil-wet to water-wet, inhibit emulsion formation, and enhance hydrocarbon recovery in high temperature and high salinity environments, improving the yield of hydrocarbons from subterranean formations.
Implementation Method 1
The surfactants can act to lower the interfacial tension between the fracturing fluid and the oil trapped within the fractures in the reservoir
Implementation Method 2
The surfactants can act to lower the interfacial tension between the fracturing fluid and the oil trapped within the fractures in the reservoir and can change the wettability of the reservoir rock
Implementation Method 3
many conventional surfactants and surfactant blends adsorb substantially onto the rock surfaces, depleting the surfactant quickly at the expense of deeper-lying fracture surfaces
Implementation Method 4
many injected surfactants facilitate underground emulsion formation between the hydrocarbon compounds and the fracturing fluid, which retards or prevents recovery of the hydrocarbon compounds
Data Source
AI summary
Disclosed herein are compositions and methods for increasing recovery, or flowback, of hydrocarbon compounds from hydrocarbon-containing subterranean fractured rock formations (tight shale reservoirs). The flowback compositions include an anionic dimer surfactant, an anionic monomer surfactant, and a demulsifier. The flowback compositions convert oil-wet rocks to water-wet, yet exhibit a low tendency of composition components to sorb to the rock. The flowback compositions do not cause formation of emulsions with hydrocarbon compounds within the subterranean fractured rock formations. The flowback composition are useful for increasing the yield of hydrocarbons recovered from tight shale reservoirs.