A conceptual model for the understanding of fouling phenomenon when using triazine based H2S scavengers

The use of triazine based H2S scavengers is known to lead to formation of fouling that may cause significant problems during oil and gas production. The fouling has been found to originate from dithiazine produced during the reaction between the triazine and H2S. When using 1,3,5-tri-(2-hydroxyethyl)-hexahydro-s-triazine and other triazines with hydroxy group functionality, the fouling has been found to be a dithiazine polymer, and the formation of this polymer has been explained by a model in which by products are formed alongside the general scavenging reaction.
In this study we have studied the applicability of the previously suggested model to describe the reaction between 1,3,5-tri-(2-hydroxypropyl)-hexahydro-s-triazine and H2S. To investigate the reaction system, electrospray ionization mass spectrometry (ESI-MS) has been employed to analyse the composition of the generated mixture as H2S is bubbled through the scavenger. The results of the study have confirmed that the suggested model is capable of explaining how the scavenger reacts with H2S, which may be used to explain from where and how the fouling originates, and how a scavenging process can be designed to avoid fouling.