GB1138654A - Explosive charges for seismic prospecting - Google Patents

Abstract

1,138,654. Explosive charges. IMPERIAL CHEMICAL INDUSTRIES Ltd. 6 Jan., 1967 [7 Feb., 1966], No. 5277/66. Heading F3A. [Also in Division H4] An explosive charge for land and marine seismic prospecting comprises a charge of high explosive having two or more initiating points each coupled with an initiating means and arranged to initiate the explosive charge at all the initiation points simultaneously or within a negligible period so that the shock waves propagating from the initiation points collide within the explosive at two or more positions simultaneously or within a negligible period. The charge may comprise an initiating line 31, Fig. 6, of detonating fuse cord and a looped line 32 also of detonating fuse cord, the detonation waves travelling in the direction of the arrows. Alternatively, the charge comprises a tape of polyethyleneterephthalate in which two sheets of the material are bonded together to sandwich therebetween an initiating line of high explosive (35, Fig. 7, not shown), and looped explosive charges (36), the explosive being contained within a preformed depression is one of the sheets. The explosive charge may also comprise a plurality of individual charges each having two or more initiating points with initiating means coupled to each point and arranged to initiate the individual charges so that the shock waves propagating therefrom collide within the individual charges and all the collisions occur simultaneously or within a negligible period. The charge may comprise initiating lines of fuse cord 27, Fig. 5, and transverse lengths 28 of fuse cord or; two initiating lines of fuse cord (24, Fig. 4, not shown) and looped lengths (23) of fuse cord or; two initiating lines of fuse cord (10 and 11, Fig. 1, not shown) threaded through the opposite ends of plastic explosive charges (12), (13) and (14). The individual charges and the initiating lines may be sandwiched in an envelope of sheeted plastics material e.g. polyethylene, polypropylene, polyvinyl chloride, polymethylmethacrylate or polyethyleneterephthalate strengthened with wire or textile yarn and arranged in the form of a flexible tape.