Abstract: A carbonaceous deposit is retorted in an array of in-situ retorts comprising rectangular retorts arranged in rows. Adjacent rows of retorts are separated by an unbroken pillar extending the length of the rows. The bottoms of the in-situ retorts slope downwardly from a first side to the opposite side. An exhaust tunnel for the deliver of products from the retort located below the bottom of the retort extends longitudinally of the row with its outer wall approximately in alignment with, but not extending laterally beyond, the pillar to maintain the integrity of the pillar. The system is especially advantageous in the retorting of oil shale and is described in detail for that application.

Abstract: A method of producing fluid fuels from carbonaceous deposits such as oil shale, heavy oils and coal by in-situ retorting of the carbonaceous deposit in rubblized in-situ retorts utilizes a plurality of such retorts. The retorts are subjected to a sequence of preparation for rubblization, rubblization and combustion of carbonaceous material to supply heat to produce a fluid fuel from kerogen in the carbonaceous deposit. At least one completely rubblized retort is maintained throughout its entire volume under the inlet pressure of the combustion air between retorts in which rubblization or stopping is taking place and retorts in which the combustion of the carbonaceous deposit is proceeding to prevent flow of toxic gases from the retort in which combustion is proceeding to a retort in which preparation for rubblization and rubblization are occurring. The invention is described in detail for the recovery of shale oil from oil shale deposits.

Abstract: In-situ retorts of elongated rectangular shape in horizontal cross section are constructed in subsurface carbonaceous deposits in a plurality of parallel rows in each of which the retorts are arranged end-to-end. The rows are separated by unbroken pillars extending upwardly from rock that is not undermined or penetrated by retorts or tunnels. The ceilings of the retorts slope upwardly at an angle of at least 40.degree. with the horizontal to an apex or crown running longitudinally of the retorts to minimize the danger of roof collapse and provide a broadened pillar through which cross drifts opening into the crown of the retort extend for supplying combustion air. The crown of the ceiling is rounded to minimize concentration of the forces imposed by the overburden.

Abstract: An underground deposit of a carbonaceous material is retorted in an array of in-situ retorts arranged in a plurality of parallel rows. Each row of retorts is separated from adjacent rows by a pillar that extends unbroken for the length of the row. An apex drift extends longitudinally of each row and forms the crown of the retorts in that row. Combustion air for the retorting of the deposit in rubblized retorts in one row is supplied through the apex drift of an adjacent row. Delivery of combustion air into the crown of a retort for the retorting of the rubblized oil shale is through cross drifts from the apex drift of the adjacent row of retorts. Following combustion of the deposit in retorts in the first row, retorts are constructed and rubblized in a second row with the apex drift through which air had previously been supplied forming the crown of the retorts in the second row. Air for retorting deposit in the second row of retorts is delivered through a third apex drift.