Encapsulated Cement Additives with Crosslinked Polymer Shell

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Solution Overview

Problem

Cement slurry design faces challenges with excessive viscosities during mixing due to viscosifiers and competitive adsorption issues between additives, leading to impractical sequential addition methods, which hinder effective cement placement and sealing in downhole conditions.

Innovation Solution

Encapsulating solid cement additives with a crosslinked polymer shell formed by reacting hydrophobic and hydrophilic film-forming monomers, allowing controlled release of additives, such as set accelerators and viscosifying agents, to address viscosity and adsorption problems while maintaining effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If viscosifiers are added to cement slurry to compensate for thermal thinning during pumping, then the slurry can be pumped downhole without excessive injection pressures, but the slurry viscosity becomes excessively high at mixing time

Engineering Contradiction:

Improvepumping capabilityVSAvoidslurry viscosity

Core Design Contradiction:

PowerVSStress or pressure

Solution Approach 1:

The additive is segmented into multiple functional components with different release rates. The encapsulated additive contains a core material surrounded by a shell with controlled permeability, allowing the additive to be released in stages: initially providing viscosity control during pumping, then gradually releasing set control functionality during hydration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The additive is pre-encapsulated in a protective shell before being added to the cement slurry. This preliminary encapsulation allows the additive to survive the mixing and pumping process without premature activation, then releases its functionality at the appropriate time and location (downhole) when needed.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If multiple additives are added sequentially to cement slurry to avoid competitive adsorption, then additive effectiveness is improved, but the operation becomes impractical

Engineering Contradiction:

Improveadditive effectivenessVSAvoidadditive addition process

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

Multiple additives with different functions (set control, viscosity control, fluid loss control) are combined into a single encapsulated additive particle. The encapsulated structure allows these different chemicals to be delivered simultaneously to the cement slurry without competitive adsorption, simplifying the addition process to a single step while maintaining individual effectiveness.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The encapsulated shell acts as an intermediary carrier that protects the additive chemicals from premature interaction with cement surfaces and from each other. This intermediary structure allows multiple additives to coexist in the slurry without competitive adsorption, then releases them in a controlled manner to achieve their respective functions.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 encapsulated additives provide controlled release of cement additives, reducing slurry viscosity and enhancing additive performance, allowing for safer and more efficient cement placement and sealing in downhole environments.

Implementation Method 1

reacting the base film-forming monomer and the overlay film-forming monomer to produce a polymer shell. The polymer shell includes a crosslinked polymer.

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Implementation Method 2

The polymer shell has a permeability to water allowing controlled release of the solid cement additive.

Methodology Applied

Scientific EffectPermeation: Permeation

Data Source

PatentUS10988662B2Composition of encapsulated chemical additives and methods for preparation of the same

Publication Date: 2021.04.27 SAUDI ARABIAN OIL CO

AI summary

Embodiments provide a method of encapsulating a solid cement additive. The method includes the step of applying a base film-forming monomer to the solid cement additive. The method includes the step of forming a coating layer surrounding the solid cement additive. The coating layer includes the base film-forming monomer. The method includes the step of applying an overlay film-forming monomer to the coating layer surrounding the solid cement additive. The method includes the step of reacting the base film-forming monomer and the overlay film-forming monomer to produce a polymer shell. The solid cement additive includes solid particles useful in cementing applications. The polymer shell includes a crosslinked polymer. The polymer shell surrounds the solid cement additive. The polymer shell has a permeability to water allowing controlled release of the solid cement additive.