Our research project aims to understand the thermodynamic and structural properties of the supercritical fluids in a complex environment. These particular fluids are common in different technologies, in particular for the development towards more environmentally friendly industrial processes. To assess the validity of this strategy, we need to elucidate the structure and the thermodynamics of the supercritical fluids within these multiscale reservoirs. In our group, we are developing the classical density functional theory (cDFT), a powerful statistical field theory based on the molecular density. The cDFT is based on a minimization process which gives (theoretically) the same results as molecular dynamics simulations, but at a cost at least 10,000 times smaller! The key challenge is to construct the best density functional, and in particular its excess contribution. We have already started to build the functional for the supercritical CO2, but for now limited to only one thermodynamic condition. Our project is to extend our functional for several conditions, relying on the statistical physics of (molecular) liquids. According to the PhD student interests, the project can then evolve in different directions: (i) the development of the cDFT in the near-critical region; (ii) the extension of cDFT for a mixture of supercritical fluids; or (iii) the applications to evaluate the properties of the supercritical fluids in confinement.