In situ oil shale retort system

Abstract

In situ oil shale retorts are formed in spaced apart rows, with adjacent rows of such retorts being separated by load-bearing barrier pillars of unfragmented formation sufficiently strong for preventing substantial subsidence at the ground surface. Each retort contains a fragmented permeable mass of formation particles containing oil shale. Separate air level drifts are excavated on an upper level of the retorts within alternating barrier pillars, and separate production level drifts are excavated at a lower production level of the retorts within intervening barrier pillars between the barrier pillars having the air level drifts. Each air level drift extends between a pair of adjacent rows of retorts adjacent upper edges of the retorts in the adjacent rows, and each production level drift extends between a pair of adjacent rows of retorts adjacent lower edges of the retorts on sides of the retorts opposite the air level drifts. During retorting operations, air is introduced along the upper edge of each retort through lateral air inlet passages extending from the adjacent air level drift. Off gas and liquid products are withdrawn from each retort through one or more lateral production level passages extending from the lower edge of the retort to the adjacent production level drift. Withdrawal of off gas along the lower edge of each retort opposite the upper edge where air is introduced causes a generally diagonal flow pattern of combustion gas through the fragmented mass from one upper edge toward the opposite lower edge of the retort.