Influence of Adding Asphaltenes and Gas Condensate on CO2 Hydrate Formation in Water-CO2-Oil Systems

Gas hydrate formation is a huge flow assurance problem in offshore production of oil and gas. However, there have been some reported cases in oil-dominated systems where the hydrates do not form, even though the high-pressure and low-temperature environments induce favorable thermodynamic conditions. The reason for this unexpected result seems to be related to the presence of natural chemical compounds in crude oils that prevent the hydrates' nucleation and agglomeration. Because the number of works in this specific topic are scarce, in the present work, we study the role played by saturates (hydrocarbon compounds) and asphaltenes (heterocyclic compounds), which are commonly present in crude oil, on hydrates that are formed from CO2 molecules in water-CO2-oil systems. Our tests were carried out in an assembly composed of a rotational rheometer with a magnetic pressure cell, which was connected to a high-pressure system. Our main results are displayed in terms of viscosity as a function of time at constant shear rate, pressure, and temperature. In this kind of experiment, hydrate formation is associated with a jump of viscosity. Our data suggest that asphaltenes retard the CO2 hydrate nucleation and formation in the crude oils studied in this work.