Three-dimensional structure of the siskin green river oil shale kerogen model: A comparison between calculated and observed properties

Three-dimensional (3D) structural models of the Green River kerogen based on the two-dimensional (2D) structure proposed by Siskin were generated using a combination of ab initio and molecular mechanics calculations. Several initial monomer conformations were generated using the simulated annealing procedure, followed by minimization via quantum mechanical calculations. ¹³C solid state nuclear magnetic resonance (SSNMR) spectra and atomic pair distribution functions (PDFs) were calculated based on these 3D models and compared to experimental results obtained on a Green River kerogen sample. The results show reasonably good agreement between calculated and experimental results, showing that this type of 3D modeling can be of value in the evaluation of 2D models. Moreover, this paper establishes a general methodology to develop 3D models for any existing or future 2D model of kerogens.