Slow-Reacting Acid Retarder Compositions for Deeper Carbonate Penetration
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Solution Overview
Problem
Existing acidizing methods, particularly those using organic acids at high temperatures, suffer from poor rock dissolution efficiency, necessitating the development of slower reacting acid systems for effective treatment of carbonate formations.
Innovation Solution
A well treatment fluid comprising an acid retarder composition with nitrogen-containing derivatives of carbonic acid, quaternary ammonium compounds, and viscoelastic surfactants is used to control acid reactivity, allowing deeper penetration and longer wormhole creation in subterranean formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If organic acids are used at high temperatures for matrix acidizing, then the treatment can be applied to carbonate formations, but the rock dissolution efficiency is poor
Solution Approach 1:
The patent changes the chemical parameters by using hydrochloric acid instead of organic acids, and adjusts the reaction rate parameters by incorporating acid retarders (urea, quaternary ammonium compounds, surfactants) to control the dissolution speed, thereby achieving both adaptability to carbonate formations and improved dissolution efficiency
Solution Approach 2:
The patent creates a composite acidizing system by combining hydrochloric acid with multiple acid retarders (urea, quaternary ammonium compounds, and surfactants) to form a synergistic mixture that provides both effective carbonate dissolution and controlled reaction rate
2Productivity
If faster reacting acid systems are used, then rock dissolution is more effective, but the acid penetrates less deeply into the formation
Solution Approach 1:
The patent applies dynamics by making the acid reaction rate adjustable through the inclusion of acid retarders that can be depleted over time, allowing the system to transition from slow initial reaction (enabling deep penetration) to faster reaction (enabling effective dissolution) as the treatment progresses
Solution Approach 2:
The patent uses acid retarders to delay the acid reaction initially, allowing the acidizing fluid to penetrate deeper into the formation before the dissolution reaction fully activates, thereby achieving both deep penetration and effective rock dissolution
3Productivity
If acid reaction rate is increased, then wormhole formation is more effective, but the wormholes branch more extensively
Solution Approach 1:
The patent applies local quality by using viscoelastic surfactants that create non-uniform fluid viscosity distribution, causing the acid to preferentially flow through specific pathways (wormholes) rather than distributing uniformly, thereby forming fewer but more effective wormholes with reduced branching
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 composition achieves enhanced rock dissolution with reduced branching, enabling deeper penetration and longer wormhole formation, thereby improving the efficiency of acidizing treatments.
Implementation Method 1
acid retarder composition with nitrogen-containing derivatives of carbonic acid, quaternary ammonium compounds, and viscoelastic surfactants is used to control acid reactivity
Implementation Method 2
The acid then reacts with soluble substances of the formation, creating pathways for oil conductivity
Implementation Method 3
the viscoelastic surfactant used increases the viscosity of the fluid as the acid is spent dissolving away the matrix rock
Data Source
AI summary
Provided is an acid retarder composition, a well treatment fluid, and a method of treating a subterranean formation for slow-reacting acidizing operations. An acid retarder composition for acidizing a subterranean formation includes a nitrogen-containing derivative of carbonic acid, a quaternary ammonium compound, and a surfactant. Well treatment fluids include an aqueous medium, an acid, and an acid retarder composition including a nitrogen-containing derivative of carbonic acid, a quaternary ammonium compound, a surfactant. Methods of treating a subterranean formation include injecting a well treatment fluid including an aqueous medium, an acid, and an acid retarder composition including a nitrogen-containing derivative of carbonic acid, a quaternary ammonium compound, and a surfactant into a subterranean formation.