Chlorite-Chlorate Biocide Formulation for Extended Well Activity
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Solution Overview
Problem
Oxidizing biocides like chlorine dioxide have a short half-life due to reactivity with sulfides and ferric compounds in subterranean oil and gas formations, limiting their antimicrobial effectiveness in hydraulic fracturing and well remediation.
Innovation Solution
A formulation combining sodium chlorite and sodium chlorate in specific weight ratios, mixed with a Brønsted-Lowry acid to generate chlorine dioxide, extending the antimicrobial activity by providing residual chlorite and chlorate ions that continue to act as bactericidal agents for longer periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If chlorine dioxide is used as an oxidizing biocide, then rapid antimicrobial kill is achieved, but the duration of action is limited due to short half-life
Solution Approach 1:
The patent applies preliminary action by pre-mixing sodium chlorite and sodium chlorate in specific ratios (25:1 to 1:5) to create a reservoir of precursor ions before introducing them to the treatment site. These precursors gradually generate chlorine dioxide over time, extending the duration of biocidal activity while maintaining effective concentrations
Solution Approach 2:
The patent changes the chemical composition parameters by introducing sodium chlorate as an additional component with different decomposition kinetics. By adjusting the ratio of chlorite to chlorate and controlling acid addition rates, the system modulates the release rate of chlorine dioxide, thereby extending the duration of action while maintaining potency
2Reliability
If sodium chlorite is used alone, then antimicrobial activity is achieved, but the time of activity is limited due to reactivity with sulfides and ferric compounds
Solution Approach 1:
The patent creates a composite biocidal system combining sodium chlorite and sodium chlorate in specific weight ratios. This composite formulation leverages the rapid antimicrobial action of chlorite while the slower-decomposing chlorate extends residual activity, providing both reliability and prolonged duration in challenging oilfield environments with sulfides and ferric compounds
Solution Approach 2:
The patent ensures continuity of useful action by designing a two-stage decomposition system where chlorite provides initial rapid kill and chlorate provides extended residual activity. The gradual conversion of chlorate to active biocidal species maintains continuous antimicrobial pressure, preventing bacterial regrowth over weeks to months
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 formulation achieves extended antimicrobial activity, with chlorine dioxide providing rapid kills and chlorate ions extending the biocidal effect for weeks to months, effectively controlling bacterial growth in oilfield environments.
Implementation Method 1
Oxidizing biocides like chlorine dioxide have a short half-life due to the reactive nature of the oxidizing molecules. Sodium chlorite is used as precursor for generation of chlorine dioxide which is a classic oxidizing antimicrobial.
Implementation Method 2
The generalized reaction is as follows: 5NaClO2+4H+→4ClO2+NaCl+H2O+4Na+
Implementation Method 3
chlorine dioxide which is a classic oxidizing antimicrobial used for the sanitation of water and food
Implementation Method 4
the residual chlorite ion provides a second layer of activity where it is known to act as a bactericidal agent
Data Source
AI summary
This invention relates to the use of chlorite-based antimicrobials in a manner where the time of biocidal activity is extended for the microbial control in the water used for drilling, completion and remediation of wells. The invention involves mixing of a compatible extender in the form of sodium chlorate with sodium chlorite to form an antimicrobial formulation. This combination is used with an acid on the site to generate chlorine dioxide which is injected into the water used for hydraulic fracturing or remedial workover. The formulation is a much more effective bactericide for the subterranean oil and gas rich formations. The potency and longevity of biocidal activity is controlled by varying the ratios of chlorate and acid which provide different profiles of the antimicrobial activities.