Swellable Coated Proppant for Low Viscosity Fracturing

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Solution Overview

Problem

Fracturing of unconventional low permeability subterranean formations using low viscosity fluids, such as friction-reduced waters, is inefficient due to improper proppant placement and early screen-out, as these fluids are unsuitable for suspending proppants effectively, leading to un-propped fractures.

Innovation Solution

A method involving proppants coated with a swellable polymer that responds to acidic pH, CO2, or H2S, allowing the proppants to self-suspend in low viscosity fluids and maintain placement within fractures, preventing premature screen-out and enhancing vertical distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If low viscosity friction-reduced water is used for fracturing, then fluid flow and penetration are improved, but proppant suspension and placement deteriorate

Engineering Contradiction:

Improvefluid flow rateVSAvoidproppant placement accuracy

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

A polymer coating is applied to the proppant surface as an intermediary substance. This coating contains functional groups that interact with the friction-reduced water, enabling the proppant to be suspended and transported effectively in the low-viscosity fluid while maintaining accurate placement in the fracture.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The surface properties of the proppant are modified by applying a polymer coating that changes its interaction parameters with the fracturing fluid. The coating alters the proppant's surface charge, hydrophilicity, or other physical-chemical parameters to enable stable suspension in low-viscosity friction-reduced water.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If high viscosity gels are used to suspend proppants, then proppant placement is improved, but fluid flow and penetration into low permeability formations deteriorate

Engineering Contradiction:

Improveproppant suspension stabilityVSAvoidfluid penetration rate

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The suspension function is segmented from the bulk fluid and transferred to the proppant surface coating. Instead of requiring the entire fracturing fluid to have high viscosity, only the polymer coating on each proppant particle provides the necessary suspension properties, allowing the bulk fluid to remain low-viscosity for optimal flow and penetration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The polymer coating acts as a mediator between the proppant and the low-viscosity fracturing fluid, providing suspension stability without requiring the bulk fluid to have high viscosity. This intermediary layer enables effective proppant transport while maintaining fluid flow characteristics suitable for low permeability formations.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If proppants are placed in fractures, then fracture support is achieved, but screen-out and un-propped fractures occur due to improper placement

Engineering Contradiction:

Improvefracture support strengthVSAvoidfracture propping reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The polymer coating on the proppant provides feedback mechanisms that enhance placement accuracy. The coating may respond to downhole conditions such as pH, temperature, or salinity changes, adjusting its properties to optimize proppant suspension and placement, thereby preventing screen-out and ensuring reliable fracture propping.

Inventive Principle:

Principle #23Feedback

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 coated proppants maintain suspension in low viscosity fluids, ensuring proper placement and reducing the risk of un-propped fractures, while being stable at high temperatures and easily breakable, thus optimizing fracturing treatments.

Implementation Method 1

A method is disclosed for fracturing a subterranean formation which includes placing in the subterranean formation a proppant including a coating thereon. The coating is swellable with aqueous medium in response to a trigger including acidic pH, CO2, H2S, or a combination thereof.

Methodology Applied

Scientific EffectSwelling: Absorption (physical)

Implementation Method 2

The coating is swellable with aqueous medium in response to a trigger including acidic pH, CO2, H2S, or a combination thereof.

Methodology Applied

Scientific EffectpH response:

Implementation Method 3

The coated proppants maintain suspension in low viscosity fluids, ensuring proper placement and reducing the risk of un-propped fractures

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentUS10703965B2Proppant comprising swellable coating thereon for treatment of subterranean formations

Publication Date: 2020.07.07 HALLIBURTON ENERGY SERVICES INC

AI summary

Various embodiments disclosed relate to proppant including a swellable coating thereon for treatment of subterranean formations. In various embodiments, the present invention provides a method of treating a subterranean formation. The method includes placing in the subterranean formation a proppant including a coating thereon. The coating is swellable with aqueous medium in response to a trigger including acidic pH, CO2, H2S, or a combination thereof.