Evaluation of Triazine-Based H2S Scavengers for Stimulation Treatments

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.

A Comprehensive Review of H2S Scavenger Technologies from Oil and Gas Streams

“…It is a molten salt, and thus, the corrosion it causes can be very aggressive. These salts have demonstrated the ability to etch through the bottom of a draw line , .…”

“…This phenomenon has been substantiated by the detection of dithiazines quantities in low ppm levels in the kerosene cut from this crude unit. The monomeric dithiazines accumulate in the cooler overhead sections and further react with H 2 S to create the amorphous dithiazine polymeric deposits inside the unit , . Taylor et al described significant plugging suspected to be from amorphous dithiazines, but occurring inside an H 2 S static tower, where the lower section of the tower had become plugged with dithiazines.…”

1H NMR for quantifying sulfide trapping efficiency by using 1,3,5‐tris(2‐hydroxyethyl)‐1,3,5‐triazinane

“…Most of the traditional approaches to monitoring H 2 S removal through laboratory methods are based on the post‐treatment quantification, which involves preventive measures and special devices to prevent leakage during this determination. The main methods are based on mass loss and gravimetric assays; also, they are associated with the risky manipulation of potentially harmful products …”