Study on the Lower Limits of Physical Parameters for Heavy Oil Reservoirs during the In Situ Combustion Process.

As an effective enhanced oil recovery (EOR) method in the late stage of the steam injection process, in situ combustion (ISC) has been verified by more and more researchers owing to its high recovery efficiency and low operation cost. However, the ISC process is prone to bringing about an unfavorable result with a low sweep efficiency and even an extinction process due to the complexity and uncertainty in oil and water distribution as well as the heterogeneity of the actual reservoir. In this work, combustion tube experiments combined with numerical simulations by CMG-STARS were conducted to study the influence of a reservoir's physical parameters on the stability of ISC. It was found that the sustainability of the combustion process is sensitive to permeability and oil saturation, the lower limits of which are determined as 0.2 µm2 and 0.2, respectively. Then, a formula was preliminarily proposed as 0.25 ≤ So/K ≤ 0.8, which could be used as a reference of screening criteria in designing the ISC process.

Correction to "Molecular Dynamics Simulation of the Soret Effect on Two Binary Liquid Solutions with Equimolar n-Alkane Mixtures".

[This corrects the article DOI: 10.1021/acsomega.1c04926.].

Molecular Dynamics Simulation of the Soret Effect on Two Binary Liquid Solutions with Equimolar n-Alkane Mixtures.

Molecular dynamics is employed to simulate the Soret effect on two binary liquid solutions with equimolar mixtures: normal pentane (n-pentane, nC-5) and normal heptane (n-heptane, nC-7) molecules plus normal decane (n-decane, nC-10) and normal pentane molecules. Moreover, two coarse-grained force field (the CG-FF) potentials, which may depict inter-/intramolecular interactions fairly well among n-alkane molecules, are developed to fulfill such investigations. In addition, thermal diffusion for the mass fraction of each of these n-alkane molecules is simulated under an effect of a weak thermal gradient (temperature difference) exerting on solution systems from their hot to cold boundary sides. Finally, quantities of the Soret coefficient (SC) for two binary solutions are calculated by means of the developed CG-FF potentials, so as to improve the calculation rationality. As a result, first, it is found that molecules with light molar masses will migrate toward the hot boundary side, while those with heavy molar masses will migrate toward the cold boundary one ; second, the SC quantities indicate that they match relevant experimental determinations fairly well, i.e., trends of these SC quantities show inverse proportionality to the thermal gradient on the systems.