Thermally Activated Strong Acid Precursors for Deep Wellbore Treatment
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Solution Overview
Problem
Conventional acidizing systems for subterranean formations face limitations such as shallow penetration, corrosion of equipment, and safety concerns due to the use of weak acids, which restrict deeper formation treatment and pose handling risks.
Innovation Solution
A thermally activated strong acid precursor is used to generate a strong acid downhole, comprising compounds like SO2 and carbonyls, which react to form alpha-hydroxy sulfonic acids, reducing corrosion and allowing deeper penetration without flaking scale, and maintaining a neutral pH initially.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional aqueous acidic solutions are used for acidizing treatments, then the acid can remove formation damage and increase permeability, but the acid is spent before deeply penetrating into the formation and causes corrosion to metal goods
Solution Approach 1:
The acidizing treatment is divided into two separate stages: first injecting a corrosion-inhibiting fluid containing precursors, then injecting an activating fluid that triggers acid generation. This segmentation allows the corrosion protection function and acid generation function to be performed at different times, eliminating the contradiction between needing strong acid for permeability enhancement and avoiding corrosion during treatment.
Solution Approach 2:
The corrosion-inhibiting fluid with precursor components is injected into the formation before the activating fluid. This preliminary action establishes a protective environment and prepares the formation for subsequent acid generation, ensuring that when the strong acid is generated, the metal goods are already protected from corrosion.
2Length of stationary object
If strong acids are used to achieve deeper penetration into the formation, then permeability enhancement is improved, but corrosion to equipment and handling safety worsen
Solution Approach 1:
Precursor compounds serve as intermediaries that are injected into the formation in a stable, non-corrosive form. These precursors remain inert during injection and transport, then transform into strong acid in situ when activated by the second fluid. This intermediary approach allows the strong acid to be delivered to the formation without the corrosion and safety hazards associated with handling and injecting strong acids directly.
Solution Approach 2:
The chemical state of the acid-generating components changes from stable precursors in the first fluid to active strong acid in the second stage. This parameter change allows the system to transition from a safe, handleable state during injection to a highly reactive state only when and where needed in the formation, achieving deep penetration without the associated corrosion risks.
3Ease of operation
If conventional organic acids are used, then handling is easier, but the acid is weak and cannot deeply penetrate or generate silica dissolving acids
Solution Approach 1:
The system uses precursor compounds that can be handled easily in their stable form, then transforms them into strong acids with high dissolving power through chemical activation in the formation. This parameter change from stable precursors to active strong acid resolves the contradiction between ease of handling and effectiveness, as the strong acid is never handled directly but generated in situ.
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 solution achieves deeper penetration into subterranean formations, reduces corrosion and scale issues, and enhances safety by generating a strong acid that is less corrosive and capable of complete ionization, thereby improving wellbore permeability and production efficiency.
Implementation Method 1
a thermally activated strong acid precursor... generating a strong acid downhole
Implementation Method 2
the acidic solution may react with acid-soluble materials contained in the formation which results in an increase in the size of the pore spaces and an increase in the permeability of the formation
Implementation Method 3
aqueous acidic solutions are introduced into the wellbore or subterranean formation under pressure so that the acidic solution flows into the wellbore or pore spaces of the formation
Data Source
AI summary
An acid-generating fluid includes a thermally activated strong acid precursor. The thermally activated strong acid precursor can include a component selected from aldehydes, ketones, and combinations thereof, in combination with a precursor of a compound adapted to react to liberate sulfur dioxide; or it can include sulfur dioxide in combination with a precursor of a compound adapted to react to liberate a component selected from aldehydes, ketones, and combinations thereof.