Solubility Enhancers for Surfactant Formulations in EOR

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Solution Overview

Problem

Existing surfactant mixtures for enhanced oil recovery often face challenges in maintaining a consistent mixing ratio when injected into subterranean formations due to chromatographic separation, which affects their interfacial tension reduction properties and solubility, especially under varying temperatures and high salt content conditions.

Innovation Solution

A surfactant composition comprising a mixture of alkoxylated anionic surfactants with specific alkoxylation distributions, including a solubility enhancer that improves the solubility of the primary surfactant without significantly altering its interfacial tension reduction capabilities, maintaining effective properties across different temperatures and salt concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If surfactant mixtures are injected into subterranean formations, then interfacial tension reduction is achieved, but chromatographic separation occurs causing inconsistent mixing ratios

Engineering Contradiction:
Improveinterfacial tension reductionVSAvoidmixing ratio consistency
Core Design Contradiction:
ForceVSStability of the object's composition

Solution Approach 1:

The patent uses a composite surfactant system comprising a first surfactant (anionic, e.g., sulfate or carboxylate) and a second surfactant (non-ionic, e.g., alcohol ethoxylate or alcohol propoxylate) with specific HLB values. This composite approach ensures that the mixture maintains consistent interfacial tension reduction properties even when chromatographic separation occurs during injection, as the two surfactants work synergistically and the overall composition remains effective across varying mixing ratios.

Inventive Principle:
Principle #40Composite materials

2Force

If surfactants are used to reduce interfacial tension, then oil recovery is enhanced, but solubility problems arise under high temperature and salt content conditions

Engineering Contradiction:
Improveinterfacial tensionVSAvoidsolubility stability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent selects surfactants with specific hydrophilic-lipophilic balance (HLB) values and molecular characteristics that maintain solubility and effectiveness across a wide range of temperatures and salt concentrations. The first surfactant is chosen with an HLB value of 8-18 and the second with HLB value of 10-20, ensuring that the composition remains soluble and effective under high temperature and high salt content conditions typical of subterranean formations.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If conventional surfactant mixtures are used, then oil displacement is improved, but the mixture composition changes during injection due to chromatographic separation

Engineering Contradiction:
Improveoil displacement efficiencyVSAvoidsurfactant mixture composition
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent designs a surfactant system where the two surfactants are selected to have compatible molecular structures and properties that minimize chromatographic separation. By choosing surfactants with appropriate HLB values and molecular weights, the mixture maintains more uniform composition during injection, ensuring consistent oil displacement efficiency throughout the formation.

Inventive Principle:
Principle #33Homogeneity

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 surfactant composition effectively reduces crude oil-water interfacial tension to less than 0.1 mN/m, enhancing oil recovery by maintaining optimal surfactant properties and stability even under stringent conditions, such as high temperatures and high salt concentrations.

Implementation Method 1

The surfactants reduce the oil-water interfacial tension thereby mobilizing additional oil from the formation

Methodology Applied
Scientific EffectInterfacial tension reduction: Surfactant

Implementation Method 2

a solubility enhancer (B) having the general formula (II)... for enhancing the solubility of anionic surfactant (A)

Methodology Applied
Scientific EffectSolubility enhancement: Solvation

Data Source

PatentUS11225857B2Solubility enhancers on basis of allyl alcohol for aqueous surfactant formulations for enhanced oil recovery
Publication Date: 2022.01.18 BASF SE
  • US11225857B2 patent drawing
  • US11225857B2 patent drawing

AI summary

The present invention relates to a method for the production of crude oil from subterranean, oil-bearing formations comprising at least the following steps of providing an aqueous surfactant composition comprising water and a surfactant mixture, injecting said surfactant composition into the subterranean, oil-bearing formation through at least one injection well, thereby reducing the crude oil-water interfacial tension to less than 0.1 mN/m, and withdrawing crude oil from the formation through at least one production well, wherein the surfactant mixture comprises at least a surfactant (A) having the general formula R1—O—(CH2CH(R2)O)a—(CH2CH(CH3)O)b—(CH2CH2O)c—R3—Y−M+ (I) and a solubility enhancer (B) having the general formula R4—O—(CH2CH(CH3)O)x—(CH2CH2O)y—R3—Y−M+ (II), wherein R1 to R4, a, b, c, x, y, Y and M have the meaning as defined the the description and claims. The invention further relates to said aqueous surfactant composition and methods for preparing the same as well as the use of solubility enhancer (B) for enhancing the solubility of anionic surfactant (A).