PMIDA Coating for Acid Placement in Carbonate Formations

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Solution Overview

Problem

The excessive reactivity of acids with acid-reactive surfaces in subterranean treatment operations leads to undesirable effects such as bulk erosion, matrix deconsolidation, and limited acid penetration, making it difficult to effectively stimulate carbonate formations and control acid placement.

Innovation Solution

The use of N-(phosphonoalkyl)iminodiacetic acids, such as N-(phosphonomethyl)iminodiacetic acid (PMIDA), which form a protective coating on acid-reactive surfaces, suppressing acid reactivity by complexation and deposition, allowing for controlled acid diversion and prolonged acid presence in desired locations within the formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If acid is used to dissolve acid-reactive material in subterranean formation, then flow pathways are expanded and permeability is increased, but excessive reactivity leads to bulk erosion and matrix deconsolidation

Engineering Contradiction:

Improvepermeability enhancementVSAvoidbulk erosion and matrix deconsolidation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A protective coating comprising N-(phosphonoalkyl)iminodiacetic acid or a salt thereof is applied to the acid-reactive surface to act as an intermediary layer. This coating suppresses the direct reaction between acid and the acid-reactive surface, allowing controlled acid placement and preventing excessive reactivity that would cause bulk erosion and matrix deconsolidation, while still permitting the acid to eventually react with carbonate minerals to create flow pathways.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If acid is placed in near-wellbore region to stimulate formation, then production is enhanced, but rapid acid spending precludes deeper penetration and causes near-wellbore damage

Engineering Contradiction:

Improveproduction stimulationVSAvoidacid penetration depth

Core Design Contradiction:

ProductivityVSLength of stationary object

Solution Approach 1:

The protective coating serves as a mediator that slows acid consumption in the near-wellbore region, preventing rapid acid spending. This allows the acid to penetrate deeper into the formation matrix by controlling the rate of reaction, thereby achieving both near-wellbore stimulation and deep formation penetration without causing excessive near-wellbore damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective coating is applied in advance to the acid-reactive surface before acid placement. This preliminary action prepares the surface to control acid reactivity, ensuring that when acid is subsequently placed, it will not react too rapidly in the near-wellbore region, thus enabling deeper penetration and more effective stimulation.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If strong acids are used to dissolve carbonate minerals, then wormhole formation and conductive channels are created, but excessive reactivity leads to scaling and deconsolidation

Engineering Contradiction:

Improveflow pathway creationVSAvoidscaling and deconsolidation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The protective coating comprising N-(phosphonoalkyl)iminodiacetic acid acts as an intermediary that moderates the interaction between strong acids and carbonate minerals. It allows the acid to react sufficiently to create wormholes and conductive channels for improved flow pathways, while simultaneously suppressing excessive reactivity that would lead to scaling and matrix deconsolidation.

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

This approach prevents unwanted acid reactions, promotes deeper acid penetration, reduces near-wellbore damage, and enables effective stimulation by forming a protective coating that can be removed when necessary, allowing for more efficient acid diversion and treatment of acid-reactive surfaces.

Implementation Method 1

suppressing acid reactivity by complexation and deposition

Methodology Applied

Scientific EffectComplexation:

Implementation Method 2

forming a protective coating on acid-reactive surfaces

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS9809716B2Methods and systems for protecting acid-reactive substances

Publication Date: 2017.11.07 HALLIBURTON ENERGY SERVICES INC

AI summary

Inadvertent or unavoidable contact of an acid with an acid-reactive substance may preclude the acid's use in another location where its reactivity is more desired. Excessive reactivity of acids toward acid-reactive substances may lead to undesired effects such as surface erosion, matrix deconsolidation, scaling, and the like. Methods for protecting an acid-reactive surface from excessive reaction may comprise: depositing a protective coating comprising an N-(phosphonoalkyl)iminodiacetic acid or any salt thereof onto an acid-reactive surface; and contacting a mineral acid or an organic acid with the protective coating without substantially reacting the acid-reactive surface.