EFFECTS OF TEMPERATURE ON THE INTERACTION OF WATER AND OIL COMPONENTS ON THE CARBONATED PORE WALL: MOLECULAR DYNAMICS SIMULATION STUDY

S Abdolahi and F Rashidi and R Miri, JOURNAL OF POROUS MEDIA, 25, 83-107 (2022).

DOI: 10.1615/JPorMedia.2022044472

Adsorption of oil molecules, especially surface active components, to the calcite surface plays a vital role in the wettability state and oil recovery from carbonate reservoirs. Through the simulation of classical molecular dynamics, we demonstrate the formation of adsorption sites on calcite surfaces of non-polar (decane and toluene) and polar (benzoic acid) oil molecules and the act of water molecules on detachment from the surface of adsorbed molecules. Two systems, oil-calcite and water- oil-calcite, are investigated, and the simulations are conducted at low (300 degrees K) and high temperatures (393.15 (K) over circle). The studied properties are number density, distribution of the center of mass, and radial distribution function. The results show that the minimum distance between the oxygen of calcite and oxygen of ben-zoic acid, hydrogen of decane, and toluene are 1.437, 2.437, and 2.562 angstrom, respectively. It is concluded that benzoic acid is adsorbed stronger to the calcite surface than decane and toluene at both temperatures. In the presence of water, non-polar molecules are desorbed from the surface at T = 393.15 (K) over circle, and water molecules are strongly adsorbed to the calcite surface compared to the non-polar molecules. Furthermore, it is revealed that water molecules do not desorb polar molecules from the calcite surface, even at elevated temperatures. Radial distribution function analysis indicates that the strong attachment of the polar molecule to the calcite surface is more significant than the water molecule, which implies the role of oil's polar components in changing the wettability of pore wall to oil-wet. The results of this work are applicable in further studies on using enhanced oil recovery methods to detach polar oil components from the carbonated reservoirs.

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