Mohammad Alaquib , Samyukhta Nair, Jenny Mclaren

Wettability of organic-rich mudrocks has significant impacts on multiphase fluid flow and hydrocarbon recovery. Since kerogen can constitute a significant volumetric fraction of mudrocks, the wettability of kerogen can considerably affect the wettability of organic-rich mudrocks. In a recent project, we showed using a combination of experimental methods and molecular simulation studies that kerogen type, thermal maturity, and reservoir temperature conditions affect the contact angle of water droplet on kerogen surface. This indicates that the wettability of kerogen is variable with its geochemistry and reservoir conditions. However, these studies do not consider the impact of having a third phase hydrocarbon in the reservoir system. Moreover, wettability affects the distribution of fluids in the porous media and the relative fluid mobility of reservoir fluids. However, the impact of kerogen wettability on fluid mobility is yet to be understood at a molecular level.

Therefore, in this research project, we plan to use molecular dynamics (MD) simulations to determine the impact of kerogen geochemistry and reservoir conditions on three phase contact angles of water and hydrocarbon on kerogen surface. We also use MD simulations to determine the impact of wettability on mobility of fluids in kerogen pores. We use realistic molecular models of kerogen. The chemical structure and composition of these molecular models are verified against experimental data for kerogen including Fourier transform infrared (FTIR) measurements, X-ray photoelectron spectroscopy (XPS) measurements and X-ray fluorescence (XRF) measurements. The results obtained from MD simulation will be verified against experientially measured three-phase contact angles on kerogen surface. Furthermore, wettability of kerogen surface impacts the interaction between the fluid and the kerogen pores and, therefore, affects the relative permeability/mobility of different fluids in the kerogen pore space. In this work, we simulate water and oil transport through the kerogen pores of varying hydrophilicities by using MD simulations to determine the impact of kerogen wettability on the fluid mobilities.