Digital Oil: Molecular Characterization and Model Construction

Abstract

Advancement in computational technology enabled the use of molecular scale simulations to provide information that cannot be extracted from experimental data alone. We employed molecular chemistry modeling to gain insights into microemulsion formation in chemical enhanced oil recovery (EOR) formulation design. A digital oil model with accurate representation of atomistic components of the complex crude oil is essential to simulate the molecular interactions within the crude oil, brine and surfactant system. We established an experimental strategy to identify oil components that have large contribution to microemulsion stability. We adopted the concept of crude equivalent alkane carbon number (EACN) which is a measurement of oil polarity to relate the suitability of any particular surfactant system to any given crude oil.  We constructed a two-dimensional digital oil model, with aromaticity on one axis, and the size of the molecules on the other axis.  The molecular architecture of aromatics and resin components was based on the correlation between gas chromatography retention index and estimated boiling point based on group contribution method. The digital oil models for a reservoir crude from Malaysia Basin were constructed. We obtained good agreement of the microemulsion phase bahaviour predicted from molecular chemistry modelingand determined from experiments. This indicated that the molecular characteristic of the digital oil model was captured correctly. This digital oil will be a powerful tool to analyze various microscopic properties and phenomena of crude oil.