The effect of climbing film on molybdenum disulfide nanosheets flooding in the tertiary oil recovery

With the development of nanotechnology, nanomaterials have shown good potential for enhanced oil recovery, which is of great significance for oil and gas production. Compared with nanoparticles and nanoemulsions, nanosheets have higher interfacial activity due to their two-dimensional structure, which can form a climbing film on the interface of oil-water and efficiently improve oil recovery. However, the influencing factors of the film-climbing effect and the relationship between the film-climbing effect and enhanced oil recovery are still not clear.

In this paper, small-sized water-soluble nanosheets which were molybdenum disulfide (MoS₂) nanosheets (30–50 nm) were synthesized using a one-step hydrothermal method, which have strong stability during the flooding test. And then, modifiers with different carbon chain lengths were used to modify the hydrophile-lipophile balance (HLB) of nanosheets.

Next, the influencing factors of nanosheets' climbing film were discussed, and the two-phase height index was innovatively used to characterize the strength of the nanosheets climbing film in the oil-water system. The results show that the longer the carbon chain length of the modifier, the closer the nanosheets are to neutral wet with stronger interfacial activity. In addition, molybdenum disulfide nanosheets can produce a climbing film at the oil-water interface, which is related to salinity, concentration, and diameter of test jar. In a word, the oil displacement efficiency can be characterized by the two-phase height index, and the higher the index, the higher the oil displacement efficiency. This makes us fully realize the importance of climbing film in tertiary oil recovery, and provides a new method for the effective development of oil and gas resources.