Abstract: The present invention relates to means for coupling the horizontally-directed force of a seismic transducer into the earth as a downward going shear wave. The coupling means consists of a plurality of downwardly convergent wedge-shaped earth-engaging cleats mounted on the transducer support means. The cleats differ from each other as to depth and sharpness, the sharper cleats being the deeper ones, so that they contact the earth's surface prior to the blunter ones and penetrate hard surfaces more readily. The blunter cleats, on the other hand, slow the rate of penetration in softer materials and thus prevent bottoming out. The cleats are configured so that the total edge length of the sharper cleats is less than that of the blunter ones, further insuring a high vertical loading on initial contact with hard surfaces. This construction permits efficient coupling into the earth of the horizontal force of a vibrator in soils and other earth materials varying widely in competency while minimizing bottoming out.

Abstract: The present invention relates to means for coupling the horizontally directed force of a seismic transducer into the earth with a downward-going shear wave. The coupling means consists of a plurality of downwardly-convergent, wedge-shaped, earth-engaging cleats dependently attached to the transducer support means, at least some of the cleats being provided with a plurality of downwardly projecting teeth, which may be mounted on or form a part of field replaceable cleat inserts. Extremely high unit pressures are developed on these teeth due to the hold down weight of the transducer. As a result, good earth penetration is achieved immediately on even very hard rock surfaces. The alignment of the teeth is such as to encourage the development of rock flaws or cracks oriented to accommodate the entry of the supporting cleats.

Abstract: The present invention relates to means for coupling the horizontally directed force of a seismic transducer into the earth with a downward going shear wave. The coupling means consists of a plurality of downwardly convergent wedge-shaped earth engaging cleats of differing depth mounted on the transducer support means. The lateral load-bearing surfaces of the cleats have sloping faces equally inclined to the vertical, so that they tend to compact and compress the earth to a similar degree with horizontal vibrator motion. However, on some or all of the cleats these sloping faces are interrupted by horizontal faces in a stair-case fashion so as to vary the overall sharpness of such cleats.

Abstract: Method and apparatus for heating a subterranean formation in which a plurality of wells are completed in a predetermined pattern, characterized by heating the subterranean formation by electrical conduction under conditions such that the electrical current flowing at different subterranean points in the subterranean formation, or adjacent thereto, varies at different times because of different current flow patterns to attain a more nearly uniform heating of the subterranean formation. Also disclosed are a plurality of methods and apparatus, including the preferred embodiments of this invention.