Polymer Viscosity Reduction via Brine Injection

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Solution Overview

Problem

The viscosity of polymer-containing fluids produced from oil-bearing formations using low salinity water-floods is high, making separation from oil phases difficult and reducing oil recovery efficiency due to emulsion formation upon mechanical shearing.

Innovation Solution

A process involving an ionic filter to separate source water into low salinity water and brine, mixing partially hydrolyzed polyacrylamide with the low salinity water to increase viscosity, and then using the brine to reduce the viscosity of the aqueous polymer phase, facilitating easier separation of oil and aqueous phases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If water-soluble polymer is added to increase water viscosity to reduce water fingering, then oil recovery is improved, but the viscosity of the aqueous polymer-containing phase becomes comparable to oil phase viscosity making separation difficult

Engineering Contradiction:

Improveoil recoveryVSAvoidseparation of aqueous and oil phases

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent applies parameter changes by adjusting the salinity of the aqueous phase. Brine is injected into the formation to increase the salt concentration in the produced fluid, which causes the polymer to collapse and reduces the viscosity of the aqueous polymer-containing phase. This viscosity reduction enables easy separation of the aqueous and oil phases while maintaining the oil recovery benefits of the polymer flood

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements periodic action through a two-stage injection process. First, polymer-containing water is injected to mobilize oil and improve recovery. Then, brine is injected in a subsequent stage to modify the produced fluid properties by increasing salinity, which reduces aqueous phase viscosity and facilitates separation. This periodic switching between polymer injection and brine injection resolves the contradiction

Inventive Principle:

Principle #19Periodic action

2Ease of operation

If mechanical shearing is applied to reduce viscosity of the aqueous polymer-containing phase, then separation becomes easier, but emulsion formation is induced which inhibits clean separation

Engineering Contradiction:

Improveseparation of aqueous and oil phasesVSAvoidemulsion formation

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical parameter of the aqueous phase by increasing its salinity through brine injection. This parameter change reduces polymer viscosity through charge screening and polymer collapse, enabling viscosity reduction without mechanical shearing, thereby avoiding emulsion formation while still achieving easy phase separation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical approach (mechanical shearing) with a chemical approach (salinity modification). Instead of using mechanical force to reduce viscosity, the patent uses chemical means (adding brine to increase ionic strength) to achieve viscosity reduction, which avoids the harmful side effect of emulsion formation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 process enhances the separability of oil and aqueous phases, improving oil recovery by reducing the viscosity of the aqueous polymer phase and minimizing emulsion formation, thereby increasing the efficiency of oil extraction.

Implementation Method 1

passing a portion of the source water through the ionic filter to form treated water having a reduced TDS content relative to the source water while excluding at least a portion of the source water from passing through the ionic filter to form a brine retentate having an increased TDS content relative to the source water

Methodology Applied

Scientific EffectIon Exchange: Ion Exchange

Implementation Method 2

mixing a polymer and water to form an aqueous polymer mixture, wherein the polymer increases the viscosity of the water

Methodology Applied

Scientific EffectViscometer: Viscometer

Implementation Method 3

mixing a brine having a TDS content that is at least 5,000 ppm greater than the TDS content of the aqueous phase of the fluid produced from the formation with at least a portion of the produced fluid to reduce the viscosity of the aqueous phase of the produced fluid

Methodology Applied

Scientific EffectSalinity sensitivity:

Data Source

PatentEP3060748B1Process for reducing viscosity of polymer-containing fluid produced in the recovery of oil

Publication Date: 2023.05.31 SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV

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AI summary

The present invention is directed to a process for producing a fluid containing oil and water from an oil-bearing formation and separating an oil phase and an aqueous phase from the produced fluid. An aqueous polymer mixture is formed by mixing polymer in water having a total dissolved solids content of from 200 ppm to 15,000 ppm. The aqueous polymer mixture is injected into an oil-bearing formation, and, after injecting the aqueous polymer mixture into the formation, a fluid is produced from the oil-bearing formation containing an oil phase and an aqueous polymer-containing phase. Brine is mixed with the produced fluid to enhance separation of the oil phase from the aqueous polymer phase.