Abstract: A method for creating a zone of increased permeability in a subterranean hydrocarbon-containing formation penetrated by a plurality of wellbores by penetrating the formation with a first wellbore; positioning a plurality of other wellbores about the first wellbore with each of the other wellbores having at least one substantially horizontal borehole extending therefrom into the vicinity of the first wellbore; extending a plurality of substantially horizontal boreholes from the first wellbore into the vicinity of the other wellbores; positioning explosive charges in at least a portion of the boreholes and detonating the explosive charges to produce a rubblized zone between the first wellbore and the other wellbores.

Abstract: A method for initiating combustion in a subterranean carbonaceous deposit by positioning at least two wellbores from the surface into the subterranean deposit; extending a first borehole substantially horizontally from a first wellbore into the vicinity of a second wellbore; extending a second borehole substantially horizontally from a second wellbore into the vicinity of the first wellbore; positioning an explosive charge in at least one of the boreholes; detonating the explosive charge to produce a rubblized zone between the first wellbore and the second wellbore; injecting a free-oxygen containing gas into the carbonaceous deposit through one of the wellbores; and igniting the carbonaceous deposit at one of the wellbores.

Abstract: Apparatus and method for maintaining the integrity of a cement sheath surrounding a casing in a hot subteranean zone including a layer of compressible refractory insulation surrounding the casing and at least one cement hanger slidably carried by said casing and means for limiting the movement of the hanger on the casing. The insulation layer mechanically isolates the sheath from thermal expansion of the casing and the slidable cement hanger likewise allows limited axial motion of the casing relative to the sheath without inducing tensile loads.

Abstract: In order to determine subsurface subsidence, the incremental movement of a radioactive source buried in a formation of interest is monitored by means of a gamma detector carried in a sonde on a downhole cable or tubing. The sonde is lowered to the vicinity of the buried source in either a cased or uncased borehole. A reversing motor within the sonde moves the detector up and down so that it continuously and automatically scans the formation in the vicinity of the source. The data transmitted to the surface enables detection of very small changes in the elastic properties of formation rocks, thereby permitting early warning of significant subsidents.

Abstract: Crushed mined coal, oil shale or tar sands, feedstocks are retorted in a retort using heat-carrying solids to supply at least fifty percent of the heat required to produce an average retort temperature of between 700.degree. F. (371.degree. C.) and 1200.degree. F. (649.degree. C.) to produce hydrocarbonaceous gases and oil. The hydrocarbon oils are treated in a manner such that there is produced a bottoms fraction containing organic carbon compounds having a boiling point above 950.degree. F. and particulate inorganic matter derived from the retorted material. The bottoms fraction is fed directly or indirectly into the retort in a manner such that the bottoms fraction does not contact the reheated heat carriers before the heat carrying solids are contacted with the crushed mined feedstock.

Abstract: In an oil shale retorting process, hot heat-carrying solids are cycled to a retort zone to mix with and retort crushed oil shale, thereby producing gas, oil products, and a mixture of heat-carrier solids and spent shale solids. The spent shale solids contain some rock solids which have a heavier particle weight than the heat-carrier solids. The heat-carrier solids are separated and recovered from the spent shale for recycle through the process. In one stage of the separation procedure, a mixture of heat-carrier solids and rock solids is fed to a gas fluidized bed classifier which is constructed and operated in a way such that rock solids are preferentially separated from the heat-carrier solids. The separation stage is especially suited to spherically-shaped heat-carrier solids in a size range between about 0.14 centimeters (0.055 inch) and 1.27 centimeters (0.5 inch) and having a surface area of between 10 and 150 square meters per gram.