API-RP38 (API)

What is API?

• API Media was the recommended formula by the American Petroleum Institute in the API-RP38 standard for monitoring SRB in oil and gas systems
• API is a strictly anaerobic media and is manufactured at BTS inside custom built anaerobic chambers
• The original API formulation calls for the use of a nail as a source of iron

How It Works

• API contains nutrients such as proteins, organic acids, and sulfate specially formulated to facilitate the growth of oil and gas field SRB
• The redox potential of properly made API, typically less than -300mV, will allow for the reduction of the sulfate to sulfide by SRB
• The biogenic sulfide created by SRB then reacts with dissolved iron species, as well as the iron in the nail. This reaction precipitates a black iron sulfide solid. Black precipitation in the vial is a positive indication for SRB

False Positive

If a water source inoculated into API is high in dissolved sulfide, typically over (X?), this can cause iron sulfide to form and create a false positive.