Chelating Acid Blends for Subterranean Formation Stimulation

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Solution Overview

Problem

Conventional acid stimulation operations in subterranean formations face limitations due to precipitation of mineral scale, asphaltenes, and metal complexes, which restrict their applicability to specific formation mineralogies and reduce fracture fluid conductivity.

Innovation Solution

The use of chelating acid blends comprising hydrochloric acid, hydrofluoric acid, and a chelating agent that decreases the potential for precipitation of metal ion complexes, allowing the blends to penetrate deeper into fractures and increase fracture fluid conductivity by dissolving formation mineralogy and chelating poly-valent metal ions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional acid stimulation operations are used, then acid can dissolve formation mineralogy, but mineral scale, asphaltenes, and metal complexes precipitate from the acid solution, limiting applicability to specific formation mineralogies

Engineering Contradiction:

Improveapplicability to formation mineralogiesVSAvoidprecipitation of mineral scale, asphaltenes, and metal complexes

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

A chelating agent is introduced as an intermediary substance that binds to metal ions in the acid solution, preventing them from precipitating as metal complexes. This mediator allows the acid to effectively stimulate a wider range of formation mineralogies without being limited by harmful precipitations, directly resolving the contradiction between versatility and precipitation issues.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical parameters of the acid stimulation system by adding chelating agents that change the solubility characteristics of metal ions. This parameter change transforms the solution from one that precipitates metal complexes to one that maintains metal ions in dissolved form, enabling broader applicability across different formation mineralogies.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If acid stimulation operations are used, then fracture fluid conductivity increases, but the process window is limited by precipitation of solids within the fractures

Engineering Contradiction:

Improvefracture fluid conductivityVSAvoidprocess window

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The chelating agent acts as a mediator that prevents solid precipitation within the fracture, thereby expanding the process window. By binding metal ions and preventing them from forming precipitates, the chelating agent allows acid stimulation to proceed more effectively and reliably across a broader range of conditions, enhancing both productivity and process reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If acid mixture reacts rapidly with formation mineralogy, then dissolution is efficient, but the acid penetrates less deeply into the fracture and formation porous network

Engineering Contradiction:

Improvedissolution efficiencyVSAvoidpenetration depth into fracture

Core Design Contradiction:

ProductivityVSLength of moving object

Solution Approach 1:

The addition of chelating agents changes the reaction kinetics parameters of the acid mixture. The chelating agents modify the overall reaction rate with formation mineralogy, allowing controlled dissolution that enables deeper penetration into the fracture and porous network while maintaining effective dissolution efficiency through the chelation-enhanced chemistry.

Inventive Principle:

Principle #35Parameter changes

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 chelating acid blends effectively stimulate a wider range of formation mineralogies, increase fracture fluid conductivity, and enhance hydrocarbon production by preventing metal complex precipitation, thereby improving the process window and applicability of acid stimulation.

Implementation Method 1

dissolving a fraction of a formation mineralogy of the subterranean formation with the acid mixture to increase a fracture fluid conductivity

Methodology Applied

Scientific EffectAcid dissolution: Chemical Bonding

Implementation Method 2

chelating, with the chelating agent, poly-valent metal ions released during the dissolving

Methodology Applied

Scientific EffectChelation: Chemical Bonding

Data Source

PatentUS11459501B2Chelating acid blends for stimulation of a subterranean formation, methods of utilizing the chelating acid blends, and hydrocarbon wells that include the chelating acid blends

Publication Date: 2022.10.04 EXXONMOBIL UPSTREAM RESEARCH COMPANY(US)

AI summary

Chelating acid blends for stimulation of a subterranean formation, methods of utilizing the chelating acid blends, and hydrocarbon wells that include the chelating acid blends are disclosed herein. The chelating acid blends include an acid mixture and a chelating agent or set of chelating agents. The acid mixture includes hydrochloric acid and hydrofluoric acid. The methods include providing the chelating acid blends to a wellbore of a hydrocarbon well, flowing the chelating acid blends into a subterranean formation, dissolving a fraction of a formation mineralogy of the subterranean formation with the acid mixture, and chelating poly-valent metal ions with the chelating agent. The hydrocarbon wells include a wellbore that extends within a subterranean formation, a downhole tubular that extends within the wellbore, a fracture that extends into the subterranean formation, and a chelating acid blend positioned within the fracture.