Anionic Surfactant and Cationic Polyelectrolyte Flocculation for Produced Water

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Solution Overview

Problem

Current methods for treating produced water on offshore platforms are inefficient in removing small oil droplets and suspended solids, limiting treatment capacity and compliance with environmental regulations, and require extensive equipment expansion due to slow flocculation processes.

Innovation Solution

A chemical flocculation method using a combination of anionic surfactants and cationic polyelectrolytes to form surfactant-polymer complexes, which rapidly destabilize and aggregate dispersed oil droplets, reducing residence time and increasing treatment capacity without expanding equipment area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional chemical flocculation methods are used, then treatment process is simple, but treatment capacity is limited and residence time is long

Engineering Contradiction:

Improvetreatment capacityVSAvoidresidence time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The invention changes the chemical parameters of the flocculation process by using a combination of anionic surfactant and cationic polyelectrolyte instead of conventional single reagents. This parameter change in reagent composition enables rapid flocculation with reduced residence time while increasing treatment capacity without requiring equipment expansion

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention employs a composite chemical system combining anionic surfactant and cationic polyelectrolyte that work synergistically. This composite approach creates highly effective flocs that aggregate quickly, resolving the contradiction between fast treatment and high capacity by enabling both rapid flocculation and high throughput in the existing equipment

Inventive Principle:

Principle #40Composite materials

2Productivity

If conventional flocculants are used, then equipment area is minimized, but treatment efficiency is low and cannot meet environmental standards

Engineering Contradiction:

Improvetreatment efficiencyVSAvoidequipment area

Core Design Contradiction:

ProductivityVSArea of stationary object

Solution Approach 1:

By changing the chemical parameters through surfactant-polyelectrolyte combinations, the invention achieves high treatment efficiency that meets environmental standards (42 mg/L OGC limit) within the existing equipment footprint. The enhanced flocculation kinetics and effectiveness allow the same equipment area to process water at higher efficiency rates

Inventive Principle:

Principle #35Parameter changes

3Productivity

If slow mixing and long residence time are used, then flocculation is thorough, but treatment flow rate is reduced

Engineering Contradiction:

Improvetreatment flow rateVSAvoidflocculation time

Core Design Contradiction:

ProductivityVSDuration of action of moving object

Solution Approach 1:

The invention changes the kinetic parameters of flocculation through the use of surfactant-polyelectrolyte complexes that rapidly form flocs. This parameter change reduces the required flocculation time from minutes to seconds, enabling high treatment flow rates while maintaining thorough aggregation of oil droplets and suspended solids

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The rapid flocculation mechanism allows the process to skip the traditional slow mixing and long residence time phase. The surfactant-polyelectrolyte combination creates instantaneous floc formation that rushes through the aggregation step quickly, achieving thorough treatment in a fraction of the conventional time and enabling high flow rates

Inventive Principle:

Principle #21Skipping (Rushing through)

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 method significantly enhances treatment efficiency, reducing residence time and increasing treatment capacity, producing treated water that meets environmental standards for marine disposal and reinjection, while minimizing equipment expansion and maintaining water quality.

Implementation Method 1

use of a combination of an anionic surfactant and a cationic polyelectrolyte, added together to the effluent, to generate surfactant-polymer complexes

Methodology Applied

Scientific EffectElectrostatic interaction: Ion Repulsion/Attraction

Implementation Method 2

destabilization/aggregation of dispersed oil droplets

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS20230391643A1Method of treatment of water produced by chemical flocculation using anionic surfactant and cationic polyelectrolyte and use of the same

Publication Date: 2023.12.07 PETROLEO BRASILEIRO SA PETROBRAS

AI summary

A method of treating produced water on offshore platforms and onshore facilities is described. The method can be applied to or integrated into other already-installed processes and/or technologies for the treatment of produced water, being characterized by the combined addition of anionic surfactant and cationic polyelectrolyte for the destabilization and flocculation of oily emulsions characteristic of produced water, preliminarily to the separation steps (hydrocyclones and/or flotators). The different points and alternatives of reagent injection combinations are adaptable to equipment and units already in operation.