A Study of Sulfide Control in Hydraulic Fracturing Using High Pressure High Temperature Bioreactors

Abstract Reservoir souring control is critical to successful hydrocarbon production in hydraulically fractured (HF) completions. Using proprietary high pressure and high temperature (HPHT) bioreactors, two commonly used Energy field biocides 4,4-dimethyl-oxazolidine (DMO) and didecyldimethylammonium chloride (DDAC) were evaluated for their effectiveness in controlling sulfide production under conditions mimicking HF and shale reservoirs. In this study, reactors inoculated with field isolated sulfide-producing bacteria were treated with DMO and DDAC respectively and operated at 1500psi with temperature ramped up gradually from 30°C to 60°C to reflect injection fluid temperature increase during HF. Fluid samples from reactors, including untreated controls, were taken weekly for sulfide level monitoring. The results showed that, without biocide, the control reactors soured quickly. As compared to untreated controls, both DMO and DDAC were able to control sulfide production to a much lower level. However, DMO demonstrated a quicker and more prolonged sulfide control than DDAC. This study indicates that, under HF conditions, DMO is a more effective biocide for reservoir souring control.