A multiscale approach towards additive discovery for natural gas hydrate inhibition and promotion

Research on natural gas hydrates (NGHs) has witnessed significant contribution in the recent years due to their strong impact on the oil industry, gas storage and environmental science. Particular attention has been devoted to the discovery and design of molecular additives, which can prevent NGHs build-up, the main cause of pipeline blockage. Classical molecular dynamics (MD) simulations of NGHs-additive interactions have allowed for the rationalization of the atomist details that control NGHs formation or inhibition. However, systematic screening and design of molecular additives is hindered by the empirical nature of classical force fields and the costs of free energy calculations. Here we propose a new unbiased approach to investigate NGHs-additive interactions based on a combination of multiscale techniques. Classical MD simulation data is used to generate realistic NGHs interfaces and binding sites. First-principles-based multiscale calculations, combining density and continuum embedding models are then exploited to characterize additive binding energies. Preliminary results from the characterization of quaternary ammonium salts, a class of molecular additives, on the hydrate surface in solutions of 0 and 100% watercut will be presented.