Bulk and Interfacial Properties of the Decane + Brine System in the Presence of Carbon Dioxide, Methane, and Their Mixture

Abstract

Bulk and interfacial properties of decane in the presence of carbon dioxide, methane, and their mixture nilesh choudhary, Arun Kumar narayanan nair * , Mohd fuad Anwari che Ruslan & Shuyu Sun * Molecular dynamics simulations were performed to study the bulk and interfacial properties of methane + n-decane, carbon dioxide + n-decane, and methane + carbon dioxide + n-decane systems under geological conditions. in addition, theoretical calculations using the predictive peng-Robinson equation of state and density gradient theory are carried out to compare with the simulation data.A key finding is the preferential dissolution in the decane-rich phase and adsorption at the interface for carbon dioxide from the methane/carbon dioxide mixture. in general, both the gas solubility and the swelling factor increase with increasing pressure and decreasing temperature. interestingly, the methane solubility and the swelling of the methane + n-decane system are not strongly influenced by temperature. our results also show that the presence of methane increases the interfacial tension (ift) of the carbon dioxide + n-decane system. typically, the ift of the studied systems decreases with increasing pressure and temperature. the relatively higher surface excess of the carbon dioxide + n-decane system results in a steeper decrease in its ift as a function of pressure. Such systematic investigations may help to understand the behavior of the carbon dioxide-oil system in the presence of impurities such as methane for the design and operation of carbon capture and storage and enhanced oil recovery processes.

Bulk and Interfacial Properties of Brine or Alkane in the Presence of Carbon Dioxide, Methane, and Their Mixture

“…Theoretical modeling has also proven to be very useful in studying bulk and interfacial properties of brine+CH 4 /CO 2 ,,,− and alkane+CH 4 /CO 2 ,,,,,,,− systems. Here, we concentrate on density gradient theory (DGT) combined with, for example, the cubic-plus-association (CPA), the volume translated predictive Peng–Robinson 1978 (VT-PPR78), or the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (EoS), the details of which can be found in, for example, our previous studies. ,,,,− To account for salt effects, the fugacity coefficient term of a nonelectrolyte ϕ i was estimated by where ϕ i EoS denotes the fugacity coefficient from, for example, the CPA EoS (without electrostatic effects) and γ i EL represents the Debye–Hückel activity coefficient.…”

Bulk and Interfacial Properties of the Alkane + Nitrogen System

“…The model and method were the same as previously described. ,, Alkane molecules were described using the TraPPE united atom model. − Additionally, N 2 is also described using the TraPPE model . The conventional Lorentz–Berthelot mixing rules were applied in all cases, except between unlike atoms as described elsewhere. ,,, Here, for the pair of nitrogen and carbon sites, the Lennard-Jones parameter …”

“…The statistical uncertainty is expressed in terms of the standard deviation of the mean of three independent simulation runs. Our system size is large enough to avoid the system size effect. ,− , …”

“…31 The conventional Lorentz−Berthelot mixing rules were applied in all cases, except between unlike atoms as described elsewhere. 33,43,44,52 Here, for the pair of nitrogen and carbon sites, the Lennard-Jones parameter = 0.935 ij i j . 33 We employed 450−800 alkane molecules and 600−7600 N 2 molecules for investigating the alkane + N 2 system (Figure 1).…”

“…Our system size is large enough to avoid the system size effect. 33,[41][42][43][44]53 The IFT was calculated by the following equation 53…”