Temperature-Dependent Wax Precipitation Characteristics in Gas Condensates: Composition, Aggregation, and Crystallization Patterns

Abstract

This study investigates the characteristics of the wax precipitation activity in the condensates. The patterns of wax precipitation are elucidated by analyzing the composition and amount of precipitate produced at various temperatures, verifying the influence mechanism of factors such as condensate composition and temperature on wax separation. The findings reveal that a decrease in the temperature enhances the contact of wax molecules by reducing their thermal motion, leading to wax particle precipitation. This also weakens the Brownian motion of precipitated wax, further promoting their aggregation and subsequent deposition. Consequently, the amount of wax precipitate increased as the temperature drops. Moreover, an increase in asphaltenes and resins in the condensates raises the critical crystalline radius of wax, making wax precipitation more difficult. Therefore, the amount of wax precipitate decreases as the concentration of asphaltenes and resins in the condensates increases. Additionally, because the solubilities of different hydrocarbon components change at different rates with decreasing temperature, lower carbon number hydrocarbons precipitate more actively in the early stages, with their precipitation rate declining as their concentration in the system diminishes. This relatively increases the precipitation rate of higher carbon number hydrocarbons in the later stage, increasing the proportion of high carbon number components in the composition curve of the wax deposit as the temperature decreases. Finally, the four components of the system─saturated hydrocarbons, aromatic hydrocarbons, asphaltenes, and resins─exhibit different precipitation behaviors as the temperature decreases, and their precipitation proportions show different trends at various temperatures. This study provides data to enrich the theoretical understanding of wax precipitation mechanisms in condensates under well-bore environmental conditions. It can support the development of effective wax blockage prevention strategies in reservoir development.