2nd Arabian Corrosion Conference
Control Strategies for Thermophilic Sulphate-Reducing Bacteria
Thermophilic (high temperature requiring) sulphate-reducing bacteria (tSRB) are responsible for both corrosion of the oil production facilities and souring of the produced oil. During oil recovery, a range of chemicals is injected into oil reservoirs for various operational reasons. Such chemicals may be designed to inhibit microbial growth, or to specifically inhibit general corrosion. Other chemicals such as scale inhibitors, oxygen scavengers, H2S scavengers and surfactants may also be injected. To date, there is little published data on the effect of any of these chemicals on the micro-flora that is known to exist in the oil formation.
The effect on sulphide production using a tSRB isolated from an oil bearing chalk formation was monitored in the presence of rock surfaces and individual chemicals. The presence of a surface increased sulphide production whilst oilfield chemicals produced a variety of responses, from complete inhibition to significant enhancement of sulphide production. Differences were observed within the various classes of treatment chemicals. Some molecules appeared to break down more easily than others under reservoir conditions and thus served to stimulate sulphide production. The data obtained will help to manage oil reservoirs in a more cost-effective and environmentally friendly manner, minimising both sulphide production and microbial corrosion by determining appropriate chemical selection and dosing regimes.