Cationic Polymer Brine Fluid for High-Temperature Wellbore Viscosity

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Solution Overview

Problem

Existing wellbore servicing fluids, particularly brines, face challenges with low viscosity, which limits their ability to control fluid loss and transport solids effectively at elevated temperatures, and polymers like HEC and xanthan gum lose thickening capacity and crosslink with multivalent cations, causing formation damage.

Innovation Solution

A wellbore servicing fluid comprising a cationic polymer with a molecular weight of 300,000 to 10,000,000 Daltons, specifically poly-DADMAC, is used in combination with a brine to create a non-Newtonian fluid with shear thinning behavior and thermal stability up to 500°F, maintaining solubility and suspension capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If HEC or xanthan gum polymers are used to thicken wellbore servicing fluids, then viscosity and fluid loss control are improved, but thermal stability deteriorates at temperatures exceeding 240°F for HEC and 280°F for xanthan gum

Engineering Contradiction:

Improvethermal stabilityVSAvoidthickening capacity

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the polymer by selecting cationic polymers with specific molecular weights (300,000 to 10,000,000 Daltons) and charge densities that remain soluble and effective at high temperatures up to 500°F, unlike conventional HEC or xanthan gum polymers

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite fluid system combining cationic polymer with multivalent cations (such as calcium, magnesium, or zinc ions) that enhances thermal stability while maintaining thickening capacity, preventing the polymer from degrading or crosslinking at elevated temperatures

Inventive Principle:

Principle #40Composite materials

2Loss of substance

If polymers are used to increase viscosity for fluid loss control, then fluid loss control is improved, but crosslinking with multivalent cations occurs at elevated temperatures causing formation damage

Engineering Contradiction:

Improvefluid loss controlVSAvoidformation damage

Core Design Contradiction:

Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent optimizes the charge density and molecular weight parameters of the cationic polymer to prevent crosslinking reactions with multivalent cations at high temperatures, maintaining solubility and preventing gel formation that would cause formation damage

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harmful interaction between polymers and multivalent cations into a beneficial effect by selecting specific cationic polymers that are stable in the presence of these cations, preventing crosslinking while maintaining fluid loss control capabilities

Inventive Principle:

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

3Stress or pressure

If brine is used as wellbore servicing fluid to control density and fluid loss, then density control is improved, but viscosity remains low limiting solids transport capability

Engineering Contradiction:

Improvedensity controlVSAvoidviscosity

Core Design Contradiction:

Stress or pressureVSTemperature

Solution Approach 1:

The patent changes the rheological parameters of the brine by adding cationic polymer, increasing viscosity while maintaining density control capabilities, enabling the fluid to transport solids effectively at high temperatures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite brine-polymer system that combines the density control properties of brine with the viscosity enhancement and solids suspension capabilities of cationic polymer, achieving both density control and improved solids transport

Inventive Principle:

Principle #40Composite materials

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 cationic polymer-brine composition (CPBC) exhibits enhanced viscosity and thermal stability, effectively controlling fluid loss and suspending solids, preventing formation damage, and maintaining performance across a wide temperature range.

Implementation Method 1

Polymers comprising hydroxyethyl cellulose (HEC) or xanthan gum have been used for thickening wellbore servicing fluids as they can dissolve in brines and produce shear thinning viscosity

Methodology Applied

Scientific EffectViscosifying:

Implementation Method 2

produce shear thinning viscosity

Methodology Applied

Scientific EffectShear thinning: Shear Thinning

Implementation Method 3

maintaining solubility and suspension capacity... thermal stability up to 500°F

Methodology Applied

Scientific EffectThermal stability:

Data Source

PatentUS9102865B2Wellbore servicing fluids comprising cationic polymers and methods of using same

Publication Date: 2015.08.11 CHEVRON PHILLIPS CHEMICAL COMPANY LP

AI summary

A method comprising placing a wellbore servicing fluid comprising a cationic polymer into wellbore wherein the cationic polymer has a molecular weight of from about 300,000 Daltons to about 10,000,000 Daltons. A composition comprising a wellbore servicing fluid, a cationic polymer, and a brine.