Water treatment and heating in spent shale oil retort

Abstract

An in situ fragmented permeable mass of particles containing treated oil shale is formed by excavating a void in a subterranean formation containing oil shale, explosively expanding formation toward such a void to form a fragmented permeable mass of formation particles containing oil shale, and retorting the particles containing oil shale in the fragmented mass. Water containing impurities is introduced into such an in situ fragmented permeable mass of particles containing treated oil shale, i.e., retorted or combusted oil shale or both, for disposal, purification, or generation of steam. The water introduced can be water containing hydrocarbons such as process water from retorting oil shale or water containing suspended solids such as blowdown from a steam generator. When the fragmented permeable mass is still hot from retorting, steam is generated which can be withdrawn for use in oil shale recovery operations. When the fragmented permeable mass does not contain particles at a high enough temperature for steam generation, water containing impurities can be purified by percolating it through the mass. A hot fragmented permeable mass can be used in turn for steam generation until it has cooled, then for removing impurities from water until it becomes too heavily contaminated, and finally for disposal of water containing impurities.