摘要 |
A method of forming an in situ oil shale retort with an open space or inlet plenum void between the top boundary of the fragmented permeable mass of oil shale particles and the unfragmented formation above the retort. The method comprises excavating at least one horizontal void in the formation, placing explosive into the unfragmented formation above and below the void, and then explosively expanding formation above the void prior to explosively expanding formation below the void. The additional time for expansion of formation above the void, as compared with that below the void, permits non-uniform expansion and leaves an open space over the top of the fragmented mass.
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