Abstract: The present method provides spatial sampling of a seismic wavefield on the free surface of the earth at an effective spatial sampling denser than the physical layout of the sensors. The sensors are comprised of a sensing element for vertical particle motion at the earth's surface, and a sensing element for rotational motion around a horizontal axis at the surface of the earth. Stress and wavefield conditions known at the free surface of the earth allow the rotational sensing element to yield the transverse horizontal gradient of the vertical particle motion wavefield. This horizontal gradient and the vertical particle motion data are utilized in the technique of ordinate and slope sampling to yield an improved transverse spatial sampling of the vertical particle motion wavefield. The method has a wide range of application in seismic surveys in oil and gas exploration and production.

Abstract: The process of the present invention involves the following steps:producing, as by hydrofracing, a substantially horizontal fracture in the subterranean rock mass to be processed;emplacing an explosive charge in the mass in spaced juxtaposed position to the fracture;enlarging the fracture to create a void space thereat, an initial lifting of the overburden, and to provide a free face juxtaposed to and arranged to cooperate with the emplaced explosive charge; andexploding the charge against the free face for fragmenting the rock and to distribute the space, thus providing fractured, pervious, rubble-ized rock in an enclosed subterranean chamber.Firing of the charge provides a further lifting of the overburden, an enlargement of the chamber and a larger void space to distribute throughout the rubble-ized rock within the chamber.

Abstract: A process of producing within a subterranean oil shale deposit a retort chamber containing permeable fragmented material wherein a series of explosive charges are emplaced in the deposit in a particular configuration comprising an initiating round which functions to produce an upward flexure of the overburden and to initiate fragmentation of the oil shale within the area of the retort chamber to be formed, the initiating round being followed in a predetermined time sequence by retreating lines of emplaced charges developing further fragmentation within the retort zone and continued lateral upward flexure of the overburden. The initiating round is characterized by a plurality of 5-spot patterns and the retreating lines of charges are positioned and fired along zigzag lines generally forming retreating rows of W's. Particular time delays in the firing of successive charges are disclosed.

Abstract: The subterranean fragmented and pervious zone is formed beneath an overburden which, as a first step of the process, is lifted as a substantially monolithic land mass to produce a void space and a free space proximate the rock to be fragmented, the raised overburden thus providing a substantially impervious lid or closure for the fragmented zone as formed by the present invention. Explosive charges are then placed proximate to and for blasting against the free face formed on raising the overburden. The charges are exploded to fragment the rock to distribute the space, thus producing fractured, pervious rubble-ized rock in a defined and enclosed zone. Different techniques are disclosed for the critical raising of the overburden and subsequent fragmenting of the rock.

Abstract: Subterranean mineral deposits, such as oil shale or the like, are prepared for in-situ retorting by selectively mining out an area at the base of the deposit leaving an overlying deposit supported in a suitable manner such as by a plurality of pillars. The overlying deposit is expanded in any suitable manner into the underlying area in a fashion to create a predetermined distribution of permeability from an area of low permeability to an area of high permeability. An inlet is provided at the low permeability area and an outlet at the high permeability area. A suitable medium is introduced into the deposit at the low permeability end for extracting and forcing mineral values from the deposit toward the outlet end for recovery.

Abstract: Subterranean mineral deposits, such as oil shale or the like, are prepared for in situ retorting by selectively mining out an area at the base of the deposit leaving an overlying deposit supported in a suitable manner such as by a plurality of pillars. The overlying deposit is expanded in any suitable manner into the underlying area in a fashion to create a predetermined distribution of permeability from an area of low permeability to an area of high permeability. An inlet is provided at the low permeability area and an outlet at the high permeability area. A suitable medium is introduced into the deposit at the low permeability end for extracting and forcing mineral values from the deposit toward the outlet end for recovery. .Iadd.