Abstract: A shaped charge is provided which includes features enhancing its manufacturability. In a described embodiment, an oilwell perforator is provided which includes a case and a liner, at least one of which is a molding. The molding has a metal loaded polymer matrix.

Abstract: The present invention relates to a structure of slackening type blasting method and mat for excluding a part of sloping surface formed by base rock layer at one side or both sides of road upon establishing or expanding of the road or for excavating a part of middle portion of base rock layer made of non-free surface, and the invention is a slackening type blasting method which makes base rock layer of blasting region to be cracked whereby slackening from mother rock comprising: a blasting hole piercing step; a blasting lead wire connecting step; a blasting mat providing step which provides a steel plate member having a magnitude capable of covering whole of multiple blasting holes formed at each blasting region connected with said blasting lead wire, and a blasting mat of weight material in which elastic member surrounding around blasting holes of blasting region is attached to bottom portion of said steel plate member and weight reinforcing member made of I type or H type beam being a weight material is weld

Abstract: A detonation system especially useful for initiating a plurality of substantially simultaneous seismic detonations includes an electric trunkline circuit disposed on the surface of a firing site containing boreholes, within which booster charges having respective top and base portions are disposed. The booster charges are connected without intervening detonators to the downhole ends of equal-sized lengths of low-energy detonating cord, the surface ends of which are connected to semiconductor bridge-initiated electric detonators connected in series in the firing circuit. The resulting system, because of the small deviation in function time of the semiconductor bridge detonators, has greatly reduced scatter time as compared to prior art systems utilizing conventional downhole electric detonators, and has a safety advantage in that the boreholes are free of detonators.

Abstract: A formation is blasted with one or more arrays of elongated, chemical, explosive charges so as to produce relatively low levels of ground vibration. The orientation and velocity of propagation of explosion in each charge and the velocity of propagation of vibration in the formation are such that, at a selected outlying location, the onset of vibration from explosion of the first negligably small increment of the charge arrives a finite time before that from explosion of the last negligably small increment. The charges of each array are fired in accurately-timed sequence, with the times between initiations chosen so that, at the outlying location, the onset of vibration from explosion of the last small increment of each charge, except the last charge, arrives a negligably small increment of time before the onset of vibration from explosion of the first small increment of the succeeding charge.

Abstract: A process for visualization of a blast wave, which is the shock wave resulting from an explosive charge, is practiced by observing disturbance contours on a liquid-air cloud and interpreting resulting graphical and calculated data to evaluate matters related to the explosive blast wave.

Abstract: A main charge of explosive is positioned symmetrically about a passageway-forming tubular member, such as a well pipe assembly. The charge is outwardly and radially spaced from the member and is coupled thereto by a dense medium, such as soil, which is adapted to transfer the produced explosive energy to the tubular member in the form of a pressure pulse applied by the medium. Initiation charges are supplied at the outer surface of the main charge, to initiate a detonation wave directed at the tubular member. A layer of dense medium is provided to confine the non-coupled surface of the charge and retard venting of explosive gases away from the tubular member. In the end result, concentrated, converging pressure pulses are applied to the tubular member on detonation, to cause it to be symmetrically crimped to restrict the passageway.

Abstract: An electronic detonator system 10 comprises a remote RF transmitter 11 and a transportable housing 12 comprising means 13 for charging energy storage means in the detonator 15 and means 14 for programming delay time means in the detonator. The programming means 14 and charging means 13 are connected to a connector 26. Detonator 15 comprises an antenna 29, a RF receiver 30, programmable delay time means 32, a switch 33, a fuse 34 and energy storage means 35. The delay time means 32 and energy storage means 35 are connected to a connector 28. In use, connector 26 is connected to connector 28 at the blast site and storage device 35 is charged and delay time means 32 is programmed. A fire command signal is then transmitted by transmitter 11 and after the delay time, switch 33 connects storage means 35 to fuse 34 thereby to energize the fuse.

Abstract: A blasting system wherein the actuation of detonators at a plurality of blast holes is controlled by firing one or more test blasts and, at each blast hole, monitoring the resulting shock wave to derive data which is used to determine time delay criteria for the blast holes.Each detonator includes a shock sensitive device which detects the shock wave. Each detonator has on-board signal processing capability and optionally is connected to a central control computer.

Abstract: The invention provides a process for converting subterraneous ore overlain by an adjacent formation of porous rock into an enclosed zone of fragmented ore by first blasting a void space in the porous rock and secondly explosively expanding the ore into the void space. The invention also provides a process for the extraction and recovery of values from a subterraneous ore overlain by an adjacent formation of porous rock. The invention is particularly useful for the extraction and recovery of carbonaceous values from subterraneous oil shale.

Abstract: A time fuze or detonating device for unpredictably-detonating scatter ammunition, which is activatable through the intermediary of an electrical trigger signal. The time fuze or triggering device is equipped with a cyclical counter which, in dependence upon a time period which commences upon the deployment of the scatter ammunition, is supplied with counting pulses, and wherein upon the appearance of a switching information, there is counted further from an end-count position momentarily reached in the cyclical counter, into a pregiven triggering count position for the emission of the trigger signal.

Abstract: A non-electric delay blasting method is provided which comprises the use of single trunk line of detonating cord having a series of detonating relays, all of the same delay period, connected at spaced intervals along its length. Branch lines of detonating cord are connected in groups to the trunk line in the intervals between the relays and each branch line has a delay detonator of the same delay period attached thereto. The delay period of the relays is shorter than that of the delay detonators. The detonators within the groups detonate in a random manner. The method eliminates the need to use large numbers of different delay period detonators in a multi-charge blast thus simplifying preparation of the charge and reducing inventories.

Abstract: A subterranean formation containing oil shale is prepared for in situ retorting by initially excavating a lower level drift adjacent a lower portion of an in situ oil shale retort site and excavating an air level void above the retort site. An undercut is excavated below a zone of unfragmented formation remaining within the retort site above the lower drift. The undercut tapers downwardly and inwardly to an opening in the lower drift for forming a draw point for withdrawing fragmented formation particles from the retort site. Formation within the remaining zone of unfragmented formation is explosively expanded downwardly in lifts for forming a fragmented permeable mass of formation particles containing oil shale within the retort site. A plurality of vertical blasting holes drilled in the remaining zone of unfragmented formation are loaded with explosive from the air level void prior to blasting each lift.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale, a horizontally extending void is excavated within the boundaries of the retort site leaving a zone of unfragmented formation above and/or below such a void, at least one pillar of unfragmented formation is left within the side boundaries of such a void for providing temporary support for overburden above the void, such a pillar is explosively expanded so that a principal portion of the pillar fragments travel to the side boundaries of the void and such a zone of unfragmented formation is explosively expanded toward the void. Accumulation of sufficient pillar fragments adjacent the side boundaries of the retort can substantially offset a tendency for fragments of the expanded zone of formation to form a mound thereby forming a fragmented permeable mass of formation particles within the retort with a reasonably flat upper surface. Such a fragmented permeable mass is retorted in situ to produce shale oil.

Abstract: A subterranean formation containing oil shale is prepared for in situ retorting by forming a fragmented permeable mass of formation particles containing oil shale in an in situ oil shale retort site. Formation is initially excavated from the retort site for forming one or more voids extending horizontally across the retort site, leaving a zone of unfragmented formation adjacent such a void. In one ambodiment, an array of rocks bolts are anchored in at least a portion of the roof adjacent such a void for providing reinforcement of unfragmented formation above the void. Vertical blasting holes are drilled in the zone of unfragmented formation adjacent the void. Explosive is placed in the blasting holes and detonated for explosively expanding the zone of unfragmented formation toward the void, including the rock bolted portion of the roof, for forming at least a portion of a fragmented permeable mass of formation particles containing oil shale in an in situ oil shale retort.

Abstract: An apparatus for the simultaneous placement of a plurality of objects on a substantially horizontal surface is disclosed, said apparatus comprising a platform to position the objects, release mechanisms to releasably attach the objects to the platform and a system for simultaneous release of the objects.