Nitrate-Reducing Bacteria Composition for SRB Control in Fracturing Fluids
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Solution Overview
Problem
Traditional water-based fracturing fluids used in hydrocarbon-bearing formations often retain water that serves as a growth medium for sulfate-reducing bacteria (SRB), leading to reduced porosity and impaired hydrocarbon recovery, and existing biocides pose environmental concerns or lack long-term effectiveness.
Innovation Solution
A nitrate-reducing bacteria (NRB) composition is developed, comprising NRB culture and a concentrated nitrate solution, with a nitrate concentration between 10% and 50%, which is effective in controlling SRB while maintaining viability, and can be combined with molybdate or molybdate salts for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional water-based fracturing fluids are used, then hydrocarbon recovery is enabled, but sulfate-reducing bacteria grow in the retained water, reducing porosity and impairing hydrocarbon recovery
Solution Approach 1:
The patent introduces nitrate-reducing bacteria (NRB) as an intermediary organism that competes with SRB for nutrients and produces nitrite, which is toxic to SRB. The NRB acts as a mediator that protects the formation by creating an unfavorable environment for SRB through biological competition and chemical inhibition, rather than directly killing SRB with biocides.
Solution Approach 2:
The patent changes the chemical parameters of the fracturing fluid by adding concentrated nitrate solution (10-50% nitrate concentration) to the water-based fracturing fluid. This parameter change creates conditions that favor NRB growth while inhibiting SRB activity, transforming the biological environment within the formation.
2Object-affected harmful factors
If long-acting biocides such as glutaraldehyde are used to control SRB, then SRB growth is inhibited, but environmental concerns such as ground water contamination arise
Solution Approach 1:
The patent replaces persistent, environmentally harmful long-acting biocides with a biologically-based solution using NRB that naturally decompose and return nutrients to the ecosystem. The nitrate-based system is environmentally benign compared to synthetic biocides, allowing effective SRB control without long-term environmental contamination.
Solution Approach 2:
The patent converts the potentially harmful high-nitrate environment into a beneficial condition by introducing NRB that utilize the nitrate productively. The nitrate serves as a substrate for NRB growth, which in turn produces nitrite that inhibits SRB, transforming a potential pollutant into a tool for biological control.
3Object-generated harmful factors
If short-acting biocides such as oxidizers are used to control SRB, then environmental hazard is reduced, but the biocides are not active over the entire time period in which the fracturing fluid is retained by the formation
Solution Approach 1:
The patent achieves continuous SRB inhibition by introducing NRB that continuously metabolize nitrate to nitrite throughout the period that fracturing fluid is retained in the formation. Unlike short-acting biocides that deplete quickly, the NRB population persists and continuously produces nitrite, providing ongoing protection against SRB for the entire duration of fluid retention.
4Object-affected harmful factors
If high concentration of nitrate is provided to NRB, then SRB control effectiveness is improved, but large quantities of nitrate must be pumped into the formation simultaneously with NRB
Solution Approach 1:
The patent segments the nitrate delivery system by separating the NRB injection from the concentrated nitrate solution injection. The NRB are injected first or separately, and the concentrated nitrate (10-50%) is provided in subsequent stages or through separate injection points, allowing the nitrate to be delivered in manageable quantities rather than requiring massive simultaneous injection.
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 NRB composition effectively inhibits SRB growth, maintaining viability and reducing hydrogen sulfide production, outperforming traditional biocides in controlling SRB and maintaining hydrocarbon recovery, with a synergistic effect when combined with molybdate, demonstrating improved environmental safety and efficiency.
Implementation Method 1
Nitrate-Reducing Bacteria (NRB) may inhibit the growth of SRB by using a more efficient nitrate-reduction metabolic pathway than SRB
Implementation Method 2
The present disclosure also provides for a process that includes growing nitrate reducing bacteria (NRB) in a nitrate reducing bacteria media to form a NRB culture and combining the NRB culture with molybdate or molybdate salt to form a NRB composition
Data Source
AI summary
A process includes growing NRB in a nitrate reducing bacteria media to form a NRB culture and combining the NRB culture with a concentrated nitrate solution to form a NRB composition.