Salt-Controlled Acid Generation for Deep Formation Penetration
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Solution Overview
Problem
Conventional acidizing systems for subterranean formations face challenges such as limited deep penetration due to acid spending, corrosion issues with metal equipment, and safety concerns related to handling and reactivity of acidic fluids, along with suboptimal control over acid generation rates from acid-generating compounds.
Innovation Solution
The use of acid-generating fluids comprising an acid-generating compound, a base fluid, and a salt, where the salt affects the hydrolysis rate of the acid-generating compound to control the generation of acid, allowing for deeper penetration and reduced corrosion, while minimizing handling risks and optimizing acid placement in subterranean formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional aqueous acidic solutions are used for acidizing, then the acid quickly reacts with formation materials to provide immediate permeability enhancement, but the acid becomes spent before achieving deep penetration into the formation
Solution Approach 1:
The acid is generated in advance by introducing acid-generating compounds (such as esters, acid anhydrides, or acid halides) into the formation before the actual acidizing treatment. These compounds hydrolyze to form the desired acid in situ, allowing the acid to be present and reactive at the target location before formation damage occurs, thereby enabling both deep penetration and effective reaction with formation materials.
Solution Approach 2:
Acid-generating compounds serve as intermediaries that convert to the desired acid through hydrolysis reactions. These intermediary compounds can be transported deeper into the formation without reacting prematurely, then convert to active acid at the target zone, solving the contradiction between needing deep penetration and requiring immediate reactive action.
2Productivity
If conventional strong acidic solutions are used to enhance reaction effectiveness, then permeability enhancement is improved, but corrosion of metal equipment in the well bore increases significantly
Solution Approach 1:
The harmful corrosive properties of conventional strong acids are extracted or removed from the system. Instead of using pre-formed strong acids that cause immediate corrosion, the invention uses acid-generating compounds that produce the desired acid in controlled amounts at the target location, eliminating the need to handle and transport corrosive acids that would damage well bore equipment.
Solution Approach 2:
The potential harm of acid corrosion is converted into a benefit by using acid-generating compounds that only become corrosive acids after penetrating the formation. The compounds themselves are non-corrosive during transport and handling, but generate the desired corrosive acid in situ where it is needed for permeability enhancement, thus converting the harmful corrosive property into a beneficial localized action.
3Length of moving object
If conventional acidizing fluids are used to achieve deep penetration, then longer treatment time is required, but the acid reacts too quickly and becomes spent before reaching deeper zones
Solution Approach 1:
The acid-generating compounds are introduced into the formation in advance and allowed to hydrolyze and generate acid in situ before the acidizing treatment begins. This preliminary generation of acid ensures that the acid is present at the target location with the appropriate concentration and reactivity period, allowing for both deep penetration and sustained action without the acid becoming spent too quickly.
Solution Approach 2:
The physical and chemical parameters of the acid system are changed by using acid-generating compounds instead of conventional acids. These compounds can be transported deeper into the formation due to their different properties, then convert to acid with controlled reactivity rates. The hydrolysis rate of the compounds can be adjusted by selecting different compounds or modifying environmental conditions, thereby controlling the duration of acid action to match the penetration depth requirements.
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 enables deeper and more uniform acid penetration, reduces corrosion of equipment, and allows for safer handling and more effective acidization of subterranean formations, achieving longer effective fracture lengths and improved production stimulation.
Implementation Method 1
allowing the salt to affect the hydrolysis of the acid-generating compound
Data Source
AI summary
Of the many methods provided, in one embodiment, a method is provided that comprises: providing an acid-generating fluid that comprises an acid-generating compound, a base fluid, and a salt; placing the acid-generating fluid in a well bore penetrating a subterranean formation; allowing the salt to affect the hydrolysis of the acid-generating compound; and allowing the acid-generating compound to produce an acid that then acidizes at least a portion of the formation or damage contained therein.