Abstract: Methods of modeling methods of producing biocrude oil and other products from biomass using hydrothermal liquefaction (HTL) performed in a well reactor or producing hydrochar from biomass using hydrothermal carbonization (HTC) performed in a well reactor. Casing and tubing positioned in the well reactor form an annulus. The casing and tubing define an HTL or HTC reaction zone in a bottom portion of the well and a heat transfer and separation zone above the reaction zone. The well includes a cable having an electric heating element positioned in the tubing in the reaction zone. The well depth and the electrical heating element are sized to produce temperature and pressure in the reaction zone sufficient to form sub-critical water and produce a product fluid comprising the biocrude oil via HTL or hydrochar via HTC. Computer-readable media encoding the methods of modeling.