Retarded Mineral Acid Composition for Oilfield Carbonate Stimulation

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Solution Overview

Problem

Current acid treatments for hydrocarbon production face limitations such as limited radial penetration and severe corrosion due to the high reactivity of mineral acids with carbonate surfaces, especially at elevated temperatures, which restricts the effectiveness of fracture acidizing and matrix stimulation techniques.

Innovation Solution

An aqueous composition comprising a mineral acid and a fixing agent, such as an amine or amide containing compound with a dipole moment of at least 3, is used to slow down the reaction rate of the mineral acid with carbonate surfaces, forming a stable adduct that reduces proton mobility and enhances acid retardation without compromising acid strength, thereby increasing penetration depth and reducing corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If mineral acid is used for matrix stimulation and fracturing treatment, then acid penetration depth is limited due to instantaneous reaction with carbonate surface, but using organic acid or retarded acid systems provides slower reaction rate and better radial penetration

Engineering Contradiction:

Improveacid penetration depthVSAvoidreaction rate

Core Design Contradiction:

Length of moving objectVSSpeed

Solution Approach 1:

The patent introduces an intermediary substance (fixing agent) that mediates between the mineral acid and carbonate surface. This fixing agent forms a complex with the acid, reducing proton mobility and creating a retarded acid system that penetrates deeper while maintaining controlled reaction rate. The intermediary substance is the key mechanism that enables both deep penetration and manageable reaction speed.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical parameters of the acid system by introducing fixing agents that alter the acid's reaction characteristics. This modifies the reaction rate parameter and penetration behavior, transforming the acid from a highly reactive mineral acid to a retarded acid system with improved radial penetration and controlled spending rate.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If mineral acid is used at elevated carbonate reservoir temperatures, then acid reaction rate increases excessively toward carbonate, but this causes severe corrosion to pumping and wellbore tubing

Engineering Contradiction:

Improvehydrocarbon productionVSAvoidcorrosion to pumping and wellbore tubing

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The fixing agent acts as a protective intermediary between the mineral acid and the metal equipment. By forming a complex with the acid, it reduces the acid's direct corrosive action on pumping and wellbore tubing while still allowing sufficient reaction with carbonate to maintain hydrocarbon production effectiveness.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful high reactivity of mineral acid at elevated temperatures into a beneficial controlled reaction. The fixing agent transforms the excessive reaction rate into a manageable spending rate, allowing the acid to remain effective for carbonate dissolution while reducing corrosive damage to equipment.

Inventive Principle:

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

3Quantity of substance

If acid is injected at high concentration to ensure sufficient acid capacity, then radial penetration is limited due to instantaneous reaction, but diluting the acid reduces reaction rate too much

Engineering Contradiction:

Improveacid capacityVSAvoidradial penetration

Core Design Contradiction:

Quantity of substanceVSLength of moving object

Solution Approach 1:

The fixing agent serves as a mediator that allows high acid capacity to coexist with improved radial penetration. By forming a complex with the acid, it controls the spending rate to match the injection rate, enabling the acid to travel further radially while maintaining sufficient concentration for effective carbonate dissolution.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent introduces dynamic control of acid spending through the fixing agent. The complex formation creates a dynamic system where the acid is released at a controlled rate matching the injection rate, allowing the acid front to move radially outward while maintaining effective concentration at the reaction interface.

Inventive Principle:

Principle #15Dynamics

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 described solution achieves deeper acid penetration and improved hydrocarbon production by retarding the acid reaction rate, allowing for greater formation permeability and reduced corrosive effects on metallic tubing, while maintaining the acid's strength and stability.

Implementation Method 1

forming a stable adduct that reduces proton mobility and enhances acid retardation

Methodology Applied

Scientific EffectAdduct formation: Chemical Bonding

Implementation Method 2

reduces proton mobility and enhances acid retardation

Methodology Applied

Scientific EffectProton mobility reduction:

Data Source

PatentUS9920606B2Preparation method, formulation and application of chemically retarded mineral acid for oilfield use

Publication Date: 2018.03.20 SCHLUMBERGER TECH CORP

AI summary

An aqueous composition comprising a mineral acid, a fixing agent and water present in an amount sufficient to dissolve the mineral acid and the fixing agent. The fixing agent comprises at least one of an amine and/or an amide containing compound having a dipole moment of at least 3 when in the aqueous composition.