Green River oil shale, a sedimentary rock, and an agglomerate of organic kerogen and minerals is the largest reserve of shale oil in the world. The production of shale oil requires the extraction of kerogen from the rock. Our prior experiments have shown that the kerogen in the shale lies in pores of tens of nanometers and is influenced by molecular interactions with the minerals. Calcite (CaCO3) is one of the predominant minerals present in Green River oil shale, and thus finding its interaction with kerogen is important. Molecular dynamics simulation is utilized in the present study to investigate the interactions between calcite mineral and the Green River kerogen, which is type I kerogen. The CHARMm force field parameters of calcite are derived from available parameters that are based on a rigid ion model. The expanded model of calcite is merged on top of the 12-unit kerogen model to study their interactions at NTP (Normal Temperature and Pressure) conditions. All the hydrocarbon fragments of kerogen in the proximity of calcite interact with the mineral with the exception of fragment 3. Fragments having olefinic hydrocarbons are attracted to the calcite mineral. These nonbonded interactions are primarily electrostatic. An energy table is developed to reveal the interfragment energy changes inside the kerogen macromolecule, in both the absence and presence of calcite. The presence of calcite mineral brings changes in the interfragment energies within the kerogen. The larger hydrocarbon fragments and independent ammonium ions are seen to have significant interactions among themselves. These findings provide an insight into the role of calcite-kerogen interactions on calcite-kerogen binding and the interfragment energies within the kerogen, which can help identify technologies to isolate kerogen from the Green River oil shale.