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J Phys Chem B. 2019 Jan 10;123(1):277-288. doi: 10.1021/acs.jpcb.8b09777. Epub 2018 Dec 27.

Molecular Dynamics Simulation of Surfactant Flooding Driven Oil-Detachment in Nano-Silica Channels.

Tang X1,2, Xiao S1, Lei Q3, Yuan L1, Peng B3,4, He L3,4, Luo J3,4, Pei Y1.

Author information

1
Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Department of Chemistry , Xiangtan University , Xiangtan 411105 , P. R. China.
2
Department of Civil Engineering and Mechanics , Xiangtan University , Xiangtan 411105 , P. R. China.
3
Research Institute of Petroleum Exploration & Development (RIPED), PetroChina , Beijing 100083 , P. R. China.
4
Key Laboratory of Nano Chemistry (KLNC) , CNPC , Beijing 100083 , P. R. China.

Abstract

Recovery of crude oil in rock nanopores plays an important role in the petroleum industry. In this work, we carried out molecular dynamics (MD) simulations to study the process of ionic surfactant solution driven oil-detachment in model silica (SiO2) nanochannels. Our MD simulation results revealed that the oil-detachment induced by the ionic surfactant flooding can be described by a three-stage process including the formation and delivery of surfactant micelles, the surfactant micelle disintegration-spread and migration on the oil-aggregate surface, and oil molecular aggregate deformation-to-detachment. A flooding from rear (FFR) phenomenon is revealed that the surfactant molecules tend to migrate to the rear bottom of the oil molecular aggregate caused by the water flow effect and hydration of polar head groups of surfactants, which facilitate the penetration of water molecules into the oil-rock interface, and the oil molecule detachment occurs at the rear bottom of the oil molecular aggregate. The present MD simulation results also indicate that the dodecyl benzenesulfonate (SDBS) has higher oil-driven efficiency than that of dodecyl trimethylammonium bromide (DTAB). The difference of oil displacement efficiency between the two surfactants is attributed to the hydration property of the polar head groups. Compared with the -N(CH3)3+ headgroup in DTAB, the bare O atom in the -SO3- group has a stronger H bond interaction with the surrounding water molecules. The stronger interaction between the headgroup of SDBS and the adjacent water molecule results in the surfactant migrating to the rear bottom of the oil molecules more quickly, thus accelerating the detachment of oil molecules.

PMID:
30589550
DOI:
10.1021/acs.jpcb.8b09777

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