Yen–Mullins Model Applies to Oilfield Reservoirs

• Published in: Energy & fuels Vol. 34; no. 11; pp. 14074 - 14093
• Main Authors: Chen, Li, Bertolini, Andre, Dubost, Francois, Achourov, Vladislav, Betancourt, Soraya, Cañas, Jesus A, Dumont, Hadrien, Pomerantz, Andrew E, Mullins, Oliver C
• Format: Journal Article
• Language: English
• Published: American Chemical Society 19.11.2020
• Subjects: Fossil Fuels
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/acs.energyfuels.0c02937

Fluid distributions throughout oilfield reservoirs have been measured with increasing accuracy and coverage, both vertical and laterally, in recent years. Currently, a routine observation is that, when reservoir crude oils are in thermodynamic equilibrium, then the reservoir is a single flow unit with fluid flow communication, addressing the most important oil production risk associated with reservoir structure. The most accurate method of determining fluid equilibration is by measurement and analysis of the distribution of dissolved (or suspended) asphaltenes in the oil. This analysis employs the Flory–Huggins–Zuo equation of state (EoS) with its reliance on the Yen–Mullins model of asphaltene nanostructures. This capability has enabled the introduction of a new technical discipline, reservoir fluid geodynamics, which provides a significant advance in the understanding of oilfield reservoirs. Other reservoir fluid components are also measured to assess equilibration of reservoir fluids, including dissolved gas, liquid-phase components, various biomarkers, and methane isotopic ratios. Often, there is a single species of asphaltenes in the reservoir in accordance with the Yen–Mullins model (molecules, nanoaggregates, and clusters). However, for some reservoirs, two species of asphaltenes are evident. These reservoirs provide a stringent test to (1) discern nanostructures of asphaltenes and (2) determine whether there are other prominent aggregate species of asphaltenes in addition to those indicated in the Yen–Mullins model. This paper explores five reservoirs: three of these reservoirs exhibit one dominant species; two exhibit two species of the Yen–Mullins model; and none of the reservoirs exhibits additional species, providing validation of asphaltene nanostructures in the Yen–Mullins model and its application with the Flory–Huggins–Zuo EoS for novel characterization of reservoirs.