Solid Acid Chelating Agent for Subterranean Acidizing
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Solution Overview
Problem
Current acidizing methods for subterranean formations face challenges such as increased reactivity and corrosion at elevated temperatures, formation of sludge, and scale deposition, which reduce permeability and oil production, and require costly interventions for scale management.
Innovation Solution
The use of a solid acid chelating agent, specifically N-phosphonomethyl iminodiacetic acid (PMIDA), which binds to metal ions to inhibit scale formation, reduce sludge viscosity, and enhance fluid flow by differentially etching conductive patterns on rock surfaces, while being stable at high temperatures and resistant to corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If common acids (HCl, acetic acid, formic acid) are used for acidizing carbonate formations, then the acid can dissolve carbonate rock to enhance fluid flow properties, but at elevated temperatures the acid exhibits increased reactivity leading to near well-bore spending and increased corrosion
Solution Approach 1:
The patent changes the chemical parameters of the acid system by using organic acids with controlled dissociation constants and buffering agents to maintain stable pH at elevated temperatures, thereby reducing unwanted reactivity and corrosion while preserving carbonate dissolution capability for enhancing fluid flow
Solution Approach 2:
The patent introduces buffering agents as intermediaries that mediate between the acid and the carbonate formation, controlling the acid's reactivity to prevent near well-bore spending and corrosion while allowing controlled dissolution to enhance permeability and fluid flow properties
2Productivity
If high concentrations of acid (15% HCl and greater) are used to dissolve carbonate rock, then the acid can effectively create conductive flow channels, but the acid causes development of sludge when placed in contact with certain types of crude oil
Solution Approach 1:
The patent changes the chemical composition parameters by using organic acids at optimized concentrations combined with scale inhibitors and surfactants, which maintain the ability to create conductive flow channels while preventing sludge formation through controlled chemical interactions with crude oil components
Solution Approach 2:
The patent creates a composite acid system combining organic acids, scale inhibitors, and surfactants that work synergistically to dissolve carbonate rock and create conductive channels while the composite formulation prevents sludge formation through multiple mechanisms including scale inhibition and surface activity
3Object-affected harmful factors
If large acid inhibitor concentrations are used to prevent corrosion at elevated temperatures, then corrosion can be inhibited, but the high inhibitor loadings can lead to formation damage or fluid instability
Solution Approach 1:
The patent changes the temperature and pH parameters by using organic acids with appropriate dissociation characteristics and buffering systems that maintain stable fluid properties at elevated temperatures, reducing the need for high inhibitor concentrations and preventing formation damage while providing adequate corrosion protection
4Quantity of substance
If sludge is produced in crude oil during acidizing treatment, then the viscosity of the oil drastically increases, but this increase causes negative effects by dramatic decrease in formation fluid-drainage properties
Solution Approach 1:
The patent applies preliminary anti-action by incorporating scale inhibitors and surfactants into the acid formulation before treatment, which preemptively prevent sludge formation and maintain low viscosity, thereby preserving formation fluid-drainage properties and avoiding the need for remedial interventions
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 solid acid chelating agent effectively inhibits scale formation, reduces sludge formation, and enhances fluid flow and permeability, allowing for more efficient oil recovery and reduced operational costs by maintaining effectiveness at high temperatures and minimizing corrosion and the need for additional inhibitors.
Implementation Method 1
a solid acid chelating agent, specifically N-phosphonomethyl iminodiacetic acid (PMIDA), which binds to metal ions to inhibit scale formation
Implementation Method 2
The solid acid chelating agent has the ability to dissolve carbonate minerals from rock surfaces
Data Source
AI summary
Methods of acidizing subterranean formations using solid acids are described. The methods include providing a treatment fluid containing a solid acid chelating agent and introducing the treatment fluid into the subterranean formation. The solid acid chelating agent includes at least one aminopolycarboxylic acid functional group and at least one phosphonic acid functional group. The treatment fluid is substantially free of an additional acid or acid-generating compound.