Foaming characteristics of crude oil-CO2 mixture by depressurization: Influence of crude oil viscosity and wax precipitation

Effect of Temperature, Pressure, and Type of Gas Injected on the Formation and Decay of Mineral Oil-Based Foams

“…Estimating the minimum superficial velocity necessary to form foam is a quite complicated task, but the correlation presented by Pilon and Viskanta 41 can be used in this case (4) where ν ∞ is the bubble terminal speed, f(r*) is a function of dimensionless radius r*and the flow pattern, FiM is the maximum void fraction for onset of foaming, and n is a constant experimentally determined.…”

“…Foams are dispersed systems of small gas bubbles in a continuous liquid or solid phase, which may be stabilized by surfactants. , These systems can be found in many day-to-day situations, from solutions used for cleansing to fire extinguishers. However, there are unwanted foams, such as the ones that may form during primary petroleum separation process. – …”

“…In the oil industry, foams can be harmful to some production process, for example, during the separation step. – In this step, foams can be formed at the three-phase gravity separators’s inlet due to the pressure drop, forming gas bubbles that will consequently distend the gas–liquid interface causing the formation of these structures. , However, according to the patent developed by Monteiro and Silva, foams can also be formed in the separator due to gas and water injected through the lower portion of the equipment, mechanism used in order to improve the separation of a three fluid phase mixture. The formation of those structures can cause several problems in petroleum gravitational separators, such as the decrease of its capacity due to the increase in the residence time required for complete separation and due to the large volume occupied by the foams. – , In addition, foaming contributes to incorrect measurement of the level of the separator interfaces, another very common problem. Problems such as oil carry-over in the gas line can also occur, which can cause the contamination of this line, besides hydrolock in the gas compressors, or even gas carry-under in the oil line, consequently causing cavitation in the pump’s intake line. ,,,, …”

“…To this day, only Shaban’s work deals specifically with foaming in life-size separators. Nonetheless, there are other works that deal with foam formation in simpler geometries whose motivation is to simulate the formation of foams in separators. – ,– These works showed the influence of defoamers or paraffins, asphaltenes, and resins on the formation and decay of foams. However, properties such as temperature, pressure, and the type of gas injected are also important in the formation and decay of foams.…”

“…The formation of those structures can cause several problems in petroleum gravitational separators, such as the decrease of its capacity due to the increase in the residence time required for complete separation and due to the large volume occupied by the foams. [3][4][5]8 In addition, foaming contributes to incorrect measurement of the level of the separator interfaces, another very common problem. Problems such as oil carry-over in the gas line can also occur, which can cause the contamination of this line, besides hydrolock in the gas compressors, or even gas carry-under in the oil line, consequently causing cavitation in the pump's intake line.…”