Evaluation of Triazine-Based H2S Scavengers for Stimulation Treatments

Abstract

Abstract Acidizing fluids perform their functions through complicated processes, hence, require additional additives to achieve wanted goals and prevent harmful side effects. Examples of these additives are diverting agents, corrosion inhibitors, surfactants, de-emulsifiers, and iron control agents. These additives should be designed to perform in a compatible and synergetic way with other additives. In this paper, triazine-based hydrogen sulfide scavenger was investigated for its scavenging capacity in various fluid formulations and its compatibility with several additives. To determine the scavenging capacity of the scavenger, an experimental method was developed. In this method, hydrogen sulfide (H2S) was generated by reacting hydrochloric acid (HCl) with iron sulfide (FeS), passed through a solution containing a triazine-based scavenger, and trapped in cadmium sulfate (CdSO3) solution. Then, the scavenging capacity was measured using gravimetric method. Furthermore, several testing parameters were investigated including amount of generated H2S, flow rate, concentration of scavenger, and type of solvent. All experiments were carried out in and aquatic neutral and acidic solutions at an anaerobic atmosphere and ambient conditions. The second part of investigation was the compatibility of hydrogen sulfide scavenger with common acidizing additives. The objective was to determine the damaging or hindering effect caused by these additives. Tested additives were mutual solvents and quaternary ammonium corrosion inhibitors. Water was found to be a suitable solvent for the tested scavenger. In contrast, the scavenging capacity declined dramatically when HCl was used. Therefore, optimum scavenging capacity, using water as solvent, was determined based on extensive testing that included parameters such as concentration of scavenger, amount of H2S, and contact time. Also, the tested additives were found to reduce the scavenging capacity.