Surfactant-less Alkaline-Polymer Formulations for Hard Brine Recovery

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Solution Overview

Problem

Current oil recovery methods, such as surfactant flooding, face challenges with high costs due to expensive sulfonate surfactants and instability issues, especially in high-temperature applications and hard brine environments, where divalent cations can cause precipitation and reduce aqueous stability, leading to plugging and surfactant retention.

Innovation Solution

A surfactant-less alkaline-polymer composition is used, incorporating a chelating agent like EDTA to prevent divalent cation precipitation, an alkaline agent to generate in-situ soap, and a hydrophilic co-solvent to produce Winsor Type III micro-emulsions with low interfacial tensions, eliminating the need for added surfactants and overcoming stability issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If surfactants are used for oil recovery, then oil displacement efficiency is improved, but cost increases and stability deteriorates in hard brine environments

Engineering Contradiction:

Improveoil displacement efficiencyVSAvoidaqueous stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system generates its own surfactant in-situ through the reaction between alkaline agents and carboxylic acids present in the crude oil. This eliminates the need for externally added surfactants that suffer from stability issues in hard brine, while still achieving the necessary interfacial tension reduction for effective oil displacement.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention changes the chemical environment by introducing alkaline agents that react with carboxylic acids in the oil to generate soap in-situ. This parameter change (pH increase) enables the formation of effective surfactants directly in the reservoir, overcoming the limitations of pre-added surfactants in hard brine conditions.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If surfactants are used for oil recovery, then oil displacement efficiency is improved, but cost increases due to expensive sulfonate surfactants

Engineering Contradiction:

Improveoil displacement efficiencyVSAvoidcost

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of using expensive, stable surfactants that need to be injected and maintained, the system uses inexpensive alkaline agents that react with readily available carboxylic acids in the oil. The generated soap serves as a temporary but effective surfactant for the duration needed for oil displacement.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Productivity

If alkaline agents are used in hard brine, then in-situ surfactant generation is enabled, but divalent cations cause precipitation and plugging

Engineering Contradiction:

Improvesurfactant generation capabilityVSAvoidprecipitation and plugging

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The invention converts the harmful effect of divalent cations (which cause precipitation) into a beneficial effect by using them as crosslinking agents for polymer gel formation. The same cations that would normally cause plugging are instead utilized to create a beneficial gel structure that improves mobility control and enhances the overall EOR process.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This approach enables efficient oil recovery by generating surfactants in-situ, reducing interfacial tensions to less than 5 millidynes/cm, thus enhancing oil displacement efficiency without the need for expensive surfactants and improving compatibility with hard brine conditions.

Implementation Method 1

The chelating agent is operable for forming a soluble salt with the hardness ions when subjected to reservoir conditions of the hydrocarbon-bearing formation

Methodology Applied

Scientific EffectChelation:

Implementation Method 2

The alkaline agent is operable for interacting with carboxylic acid in the hydrocarbon-bearing formation at reservoir conditions of the hydrocarbon-bearing formation to generate an in-situ surfactant

Methodology Applied

Scientific EffectChemical reaction (saponification):

Implementation Method 3

The co-solvent is operable for interacting with the in-situ generated surfactant at the reservoir conditions of the hydrocarbon-bearing formation to produce an optimum surfactant

Methodology Applied

Scientific EffectMicro-emulsion formation: Microemulsion

Implementation Method 4

reducing interfacial tensions to less than 5 millidynes/cm

Methodology Applied

Scientific EffectInterfacial tension reduction: Surface Tension

Data Source

PatentUS9175207B2Surfactant-less alkaline-polymer formulations for recovering reactive crude oil

Publication Date: 2015.11.03 BOARD OF RGT THE UNIV OF TEXAS SYST

AI summary

Compositions and methods for oil recovery using a surfactant-less alkaline-polymer system in hard water or hard brine is described in the instant invention. The formulation further includes a chelating agent, an alkaline agent (which can be the same as the chelating agent), and a co-solvent. The formulations as disclosed herein are capable of forming a surfactant in-situ resulting in Winsor Type III micro-emulsions of low interfacial tension.