Oil shale retorting from a high porosity cavern

Abstract

A method of producing hydrocarbonaceous liquids and gases from subterranean kerogen-containing oil shale formations comprising (a) penetrating the oil shale deposits with at least two well bores; (b) fracturing the oil shale deposits in a lower vertical portion thereof; (c) igniting the hydrocarbonaceous deposit; (d) introducing through the first well bore a free oxygen-containing gas to the ignited point of the oil shale deposit to effect thermal decomposition of the hydrocarbonaceous material therein and to propagate a combustion zone through the fractured communication area and the second well bore, thereby forming a region of combusted shale between the first well bore and the second well bore; (e) allowing the combustion to continue until a sufficient volume of combusted shale has been formed; (f) then jetting an aqueous liquid into and through the combusted shale zone to remove the mineral residue remaining after combustion; (g) positioning conventional explosives in the oil shale deposit in the vicinity of the washed-out cavity formed in step (g) above; (h) detonating the explosives, thereby causing the oil shale deposit to be fragmented and to collapse into the cavity, thus creating a rubblized zone of relatively high permeability and porosity; (i) then igniting the oil shale and introducing a free oxygen-containing gas at the top of the rubblized zone to combust and retort the rubblized hydrocarbonaceous deposit. Alternatively, a heated liquid may be introduced at a temperature of from around 700.degree. to 1000.degree. F. to effect production of hydrocarbonaceous liquids or gases from the rubblized oil shale.