Modeling of vertical pressure distribution in large in situ retorts

Deformation of oil-shale rubble and its consequent permeability loss depends upon rock pressure. This pressure distribution in oil-shale rubble columns is therefore important to modified in-situ oil extraction from oil shale. Pressure distribution in unretorted columns of oil-shale rubble has been modeled using the theory of bins. Dependence of vertical pressure on column geometry and shale properties was examined. A major finding is that, at room temperature for a given geometry and properties, pressure approaches an asymptotic limit regardless of overburden forces. The model has been extended to include variations in density and frictional properties of shale that accompany the temperature changes occurring during retorting and this expanded model has been programmed for the CDC 7600 computer. Parametric studies with this program point up the urgent need for data on the dependence of interparticle frictional properties on temperature and pressure. Directions of further development and improvement of this modeling effort are discussed.