Methanesulfonic Acid Dissolution of Alkaline Earth Metal Sulfate Deposits
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Solution Overview
Problem
Existing methods for dissolving alkaline earth metal sulfates in underground oil and gas production systems face challenges, including secondary precipitation and low efficiency, particularly when using alkaline complexing agents like EDTA or DTPA, which can lead to clogging and require additional complex procedures.
Innovation Solution
An aqueous formulation comprising 15% to 98.98% water, 1% to 75% methanesulfonic acid, 0.01% to 5% water-miscible organic solvent, and 0.01% to 5% corrosion inhibitor, with a pH of ≤ 2.5, is used to dissolve alkaline earth metal sulfates in underground systems, preventing secondary precipitation and allowing for direct contact with formation water without pre-flushing or isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkaline complexing agents like EDTA or DTPA are used to dissolve alkaline earth metal sulfates, then dissolving capability is improved, but secondary precipitation occurs and system clogging is caused
Solution Approach 1:
The patent changes the pH parameter from alkaline (pH 8-14 in prior art) to acidic (pH 1-3 in the invention). This fundamental parameter change allows the use of acidic sulfonate compounds instead of alkaline complexing agents, thereby dissolving alkaline earth metal sulfates without causing secondary precipitation of metal hydroxides that occurs with alkaline agents.
Solution Approach 2:
The patent employs acidic sulfonate compounds (methanesulfonic, ethanesulfonic, or propanesulfonic acid) as single-use treatment formulations that dissolve deposits and are then discarded with the produced water. These acids do not require the complex regeneration systems needed for alkaline complexing agents, eliminating secondary precipitation issues.
2Productivity
If alkaline complexing agent formulations are used, then dissolving efficiency is improved, but additional complex procedures like pre-flushing and hydraulic isolation are required
Solution Approach 1:
The patent extracts and eliminates the problematic alkaline complexing agents (EDTA, DTPA) from the formulation, replacing them with acidic sulfonate compounds. This removal simplifies the treatment procedure by eliminating the need for pre-flushing to remove alkaline residues and hydraulic isolation to prevent secondary precipitation, while maintaining or improving dissolving efficiency.
Solution Approach 2:
Instead of using alkaline formulations as in conventional practice, the patent inverts the approach by using acidic formulations (pH 1-3). This inversion allows direct treatment without pre-flushing or isolation procedures, as the acidic nature prevents secondary precipitation and the sulfonate compounds provide effective dissolving capability.
3Ease of operation
If conventional acid treatments are used, then simplicity of application is improved, but effectiveness against sulfate deposits is reduced
Solution Approach 1:
The patent creates a composite chemical system by combining acidic sulfonate compounds (methanesulfonic, ethanesulfonic, or propanesulfonic acid) in specific concentrations (0.1-30% w/v). This composite formulation maintains the simplicity of acid application while achieving effectiveness against sulfate deposits through the unique chemical properties of sulfonate compounds that can solubilize calcium, strontium, and barium sulfates.
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 method effectively dissolves alkaline earth metal sulfates without causing secondary deposits, allowing for efficient removal of deposits in boreholes and reservoir rocks without the need for pre-treatment or hydraulic isolation, maintaining system connectivity and avoiding clogging issues.
Implementation Method 1
An aqueous formulation comprising 15% to 98.98% water, 1% to 75% methanesulfonic acid, 0.01% to 5% water-miscible organic solvent, and 0.01% to 5% corrosion inhibitor, with a pH of ≤ 2.5, is used to dissolve alkaline earth metal sulfates
Data Source
Figure 1~2
Figure 3
AI summary
Method for dissolving deposits containing alkaline earth metal sulphates in subterranean systems or system parts for obtaining petroleum, natural gas and/or water, in which method the deposits are treated with an aqueous formulation containing methanesulphonic acid.