Insights into the mechanism of lead sulfide pbs fouling and the influence of light distillate fraction

© Copyright 2018, Society of Petroleum Engineers. Deposition of inorganic scale on downhole completion equipment contributes to significant downtime and loss of production within the oil and gas industry. High temperature/high pressure (HT/HP) fields have reported build-up of lead sulfide (PbS) scale as a consequence of reservoir souring. This paper reports on the design of an experimental rig allowing diffusion of H2S into a scaling brine under dynamic environments. Multiphase conditions induced by introduction of a light distillate within the system were used to create an emulsion in order to reflect more accurately the scaling process occurring within sour systems. The results showed that the presence of an oil phase within the system caused the lead sulfide nano crystals to reside at the oil- water (o/w) interface; increasing surface build-up propensity through an adhesion process. Performance of a range of coatings for potential application in oilfield environments was determined through gravimetric measurements and microscopy techniques and the wettability of surfaces was shown to have a significant influence on the degree of lead sulfide deposition in a multiphase system.