Experimental Determination of Wax Appearance Temperature (WAT) in Brazilian Presalt Petroleum via HPμDSC: Effects of Pressure and Gas Composition

Considered a primary energy source, crude oil is essential for the production of industrial inputs. With the increase in investments in deepwater production systems, technological challenges emerge, especially in the exploitation of the Brazilian presalt, where the formation of hydrates and wax deposits can pose flow assurance risks. In addition to conditions that favor deposit formation, such as low seabed temperature, these fields also present a high gas/oil ratio and elevated pressuresfactors that can alter the kinetics and thermodynamics of the phenomenon. This study aims to experimentally characterize the influence of three different gases (CO₂, Natural Gas, N₂, and N₂ + <i>n</i>-hexane) at different pressuresup to 20.0 MPa gauge (MPag) on the first and second crystallization events of a dead crude oil sample from the Brazilian presalt. The experiments were conducted using HPμDSC high-pressure cells, with pressure increased by the slow and gradual injection of each gas under study. It was found that N₂ injection increases the WAT, while Natural Gas injection, in contrast, reduces the WAT. In the case of CO₂ injection, pressure intervals were observed in which WAT increases, and others in which it remains constant; this behavior was also observed for the crystallization temperature of the second event.