Internal Olefin Sulfonate Surfactant for High Salinity Recovery
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Solution Overview
Problem
Current surfactant compositions for enhanced hydrocarbon recovery are inadequate in brines with high salinity and hardness, as they suffer from insufficient brine solubility and divalent ion tolerance, leading to increased interfacial tension and reduced effectiveness in severe reservoir conditions.
Innovation Solution
A hydrocarbon recovery composition comprising high molecular weight internal olefin sulfonates, ethoxylated alcohols with specific ethylene oxide moles, and a blend of internal olefin sulfonates with varying carbon lengths is used, which is mixed with formation brine to create an injectable fluid with a low surfactant concentration, reducing interfacial tension and improving solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high molecular weight internal olefin sulfonates are used to reduce interfacial tension, then surfactant effectiveness improves, but solubility in high salinity brine deteriorates
Solution Approach 1:
The patent uses ethoxylated alcohols as intermediary substances to mediate between the hydrophobic internal olefin sulfonates and the aqueous brine phase. These cosurfactants act as molecular bridges that enhance the solubility of high molecular weight sulfonates in saline environments without compromising their interfacial tension reduction capability, thereby resolving the contradiction between surfactant effectiveness and solubility.
Solution Approach 2:
The invention creates a composite surfactant system combining internal olefin sulfonates with ethoxylated alcohols. This composite formulation leverages the synergistic effects of both components: the sulfonates provide low interfacial tension while the ethoxylated alcohols provide solubility enhancement in high salinity conditions, thus simultaneously achieving both improved effectiveness and maintained solubility.
2Stability of the object's composition
If concentration of cosurfactants is increased to maintain solubility, then solubility improves, but cost and formulation complexity increase
Solution Approach 1:
The patent optimizes the ethylene oxide to alcohol ratio (EO/A ratio) as a critical parameter to achieve effective solubility enhancement at low cosurfactant concentrations. By carefully controlling this parameter within specific ranges, the formulation achieves maximum solubility with minimal cosurfactant addition, thereby reducing both cost and formulation complexity while maintaining the required solubility performance.
3Device complexity
If existing surfactants are used in high salinity conditions, then formulation simplicity is maintained, but interfacial tension reduction capability deteriorates
Solution Approach 1:
The patent applies the local quality principle by selecting specific carbon chain lengths (C17-C24) and structures for the internal olefin sulfonates that are particularly effective in high salinity environments. This localized optimization of surfactant properties ensures that the surfactant molecules maintain their interfacial tension reduction capability even in the presence of high concentrations of divalent ions, thereby achieving reliable performance in severe reservoir conditions.
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 effectively reduces interfacial tension in high salinity and hardness conditions, enhancing hydrocarbon mobilization and production efficiency by maintaining a single-phase solution during injection, thus overcoming capillary forces and improving economic viability of hydrocarbon recovery.
Implementation Method 1
the mobilization of residual oil saturation is achieved through surfactants which generate a sufficiently (ultra) low crude oil / water interfacial tension (IFT) to give a capillary number large enough to overcome capillary forces and allow the oil to flow
Implementation Method 2
adding a solubilizer which consists of an ethoxylated alcohol wherein the alcohol before ethoxylation had an average molecular weight of at least 220, wherein the ethoxylated alcohol comprises from 5 to 9 moles of ethylene oxide per mole of alcohol
Data Source
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AI summary
The present invention provides a method of treating a hydrocarbon containing formation comprising (a) providing a hydrocarbon recovery composition to at least a portion of the hydrocarbon containing formation, wherein the composition comprises one or more internal olefin sulfonates having 17 or more carbon atoms, (b) adding water and/or brine from the hydrocarbon formation to the composition, (c) adding a solubilizer which comprises an ethoxylated alcohol wherein the alcohol before ethoxylation had an average molecular weight of at least 220 and (d) allowing the composition to interact with hydrocarbons in the hydrocarbon containing formation. The solubilizer may comprise less than 0.1 wt%, preferably from 0.02 to 0.05 wt%, of the total composition and it may have from 5 to 9 moles of ethylene oxide per mole of alcohol.