Sulfate-reducing bacteria (SRB) are anaerobic microorganisms that significantly contribute to microbial corrosion, especially in metallic infrastructures such as gas and oil pipelines. This problem becomes more critical during hydrostatic testing, when SRB-contaminated water accelerates corrosion in carbon steel pipes. In this study, water samples from deep and surface wells were analyzed using 16S rRNA gene sequencing, confirming dominant SRB strains such as Clostridium perfringens (UGWCp01, UGWCp04) and Paraclostridium (UGWPc02). To mitigate SRB activity, several chemical biocides (glutaraldehyde, isothiazolin, a bronopol–isothiazolin mix) and silver nanoparticles were tested at equal final dosages in contaminated water in contact with carbon steel specimens under anaerobic conditions. Corrosion inhibition was evaluated using potentiodynamic polarization (LSV/Tafel) and electrochemical impedance spectroscopy (EIS), and surface changes were characterized by SEM and XRD after long-term immersion simulating hydrostatic exposure. Silver nanoparticles produced the lowest corrosion current densities and the highest impedance responses, consistent with markedly reduced pitting and sulfide deposits. Overall, AgNPs showed the strongest antimicrobial and corrosion-inhibiting performance, indicating a promising alternative for protecting steel during SRB-driven hydrostatic testing.