Sodium Nitroprusside and Nitrate Metabolic Inhibition for Souring Control
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Solution Overview
Problem
The petroleum industry faces challenges in controlling souring, a process where sulfate-reducing bacteria produce hydrogen sulfide, leading to health and safety risks, oil quality deterioration, and biocorrosion, due to limitations with current biocide treatments such as non-target toxicity, high dosing requirements, and environmental concerns.
Innovation Solution
A combination of sodium nitroprusside (SNP) and nitrate is used as metabolic inhibitors in microbial cultures to ameliorate sulfide formation, effectively inhibiting sulfate-reducing bacteria in oil reservoirs and facilities, even at low concentrations, and reacting with sulfide to remove it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If biocides are applied to control sulfate-reducing bacteria, then sulfide production is reduced, but environmental toxicity and non-target effects increase
Solution Approach 1:
The patent changes the chemical parameter from traditional biocides to nitrate, which alters the mechanism of action from direct toxicity to metabolic inhibition. Nitrate competes with sulfate for electron donors and produces nitrite that inhibits the dissimilatory sulfite reductase enzyme, thereby reducing sulfide production without the broad environmental toxicity of conventional biocides
Solution Approach 2:
The patent employs nitrate as a temporary, consumable substance that is applied in pulses or continuous low doses. The nitrate is rapidly consumed by nitrate-reducing bacteria through metabolic processes, converting it to nitrite and then to nitrogen gas or ammonium, eliminating persistent environmental toxicity while maintaining sulfide control during the treatment period
2Object-affected harmful factors
If high concentrations of biocide are applied to control SRB, then sulfide production is reduced, but treatment cost and frequency increase
Solution Approach 1:
The patent changes the concentration parameter from high-dose biocide application to low-dose nitrate application. Nitrate is applied at concentrations of 1-100 mg/L, which is significantly lower than typical biocide concentrations, yet achieves effective sulfide control through metabolic inhibition mechanisms that amplify the effect at low concentrations
Solution Approach 2:
The patent employs nitrate-reducing bacteria that naturally consume nitrate through their metabolic processes. These bacteria convert nitrate to nitrite and subsequently to nitrogenous products, creating a self-regulating system where the microorganisms themselves consume the treatment substance, eliminating the need for high external dosing and frequent applications
3Object-affected harmful factors
If nitrate is applied to enrich nitrate-reducing bacteria, then sulfide production is reduced, but application cost increases
Solution Approach 1:
The patent employs nitrate-reducing bacteria that naturally consume nitrate through their metabolic processes. These bacteria convert nitrate to nitrite and subsequently to nitrogenous products, creating a self-regulating system where the microorganisms themselves consume the treatment substance, eliminating the need for high external dosing and frequent applications
Solution Approach 2:
The patent optimizes the nitrate concentration parameter to balance effectiveness and cost. By applying nitrate at low concentrations (1-100 mg/L) and utilizing the natural metabolic consumption by indigenous nitrate-reducing bacteria, the system achieves cost-effective sulfide control without requiring expensive high-dose applications
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 combination of SNP and nitrate synergistically inhibits microbial metabolism, reducing sulfide production and corrosion, while minimizing environmental impact and operational costs, with SNP concentrations as low as 1 ppm effectively controlling souring in oil bioreactors and high-temperature conditions.
Implementation Method 1
A combination of a nitroprusside, such as sodium nitroprusside (SNP; Na2[Fe(CN)5NO].2H2O) and a nitrate, may be used as metabolic inhibitors of microbial cultures
Implementation Method 2
Nitrate application enriches nitrate-reducing bacteria (NRB), which inhibit SRB by outcompeting for electron donors, increasing the redox potential
Implementation Method 3
SNP has been reported to react with H2S biosynthesized in mammals during enzymatic metabolism of sulfhydryl proteins
Data Source
AI summary
Combinations of a nitroprusside, such as sodium nitroprusside (SNP; Na2[Fe(CN)5NO].2H2O) and a nitrate, are provided, together with methods for the combined use of the nitroprusside and the nitrate as metabolic inhibitors of microbial cultures. The microbial cultures may include sulfate reducing bacteria (SRB) in aqueous culture. This metabolic inhibition may for example be implemented in the presence of a hydrocarbon, for example in an oil reservoir or in oil field systems and facilities. When applied to an SRB culture in the presence of a hydrocarbon, the combination of the nitroprusside and the nitrate may accordingly be used to ameliorate the biological formation of sulfides, particularly hydrogen sulfide.