US3500949A - Marine seismographic prospecting - Google Patents

Marine seismographic prospecting Download PDF

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Publication number
US3500949A
US3500949A US691395A US69139567A US3500949A US 3500949 A US3500949 A US 3500949A US 691395 A US691395 A US 691395A US 69139567 A US69139567 A US 69139567A US 3500949 A US3500949 A US 3500949A
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US
United States
Prior art keywords
charge
explosive
bubble
charges
prospecting
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US691395A
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English (en)
Inventor
Stewart Paterson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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Filing date
Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
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Publication of US3500949A publication Critical patent/US3500949A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/02—Generating seismic energy
    • G01V1/104—Generating seismic energy using explosive charges
    • G01V1/13—Arrangements or disposition of charges to produce a desired pattern in space or time
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B3/00—Blasting cartridges, i.e. case and explosive
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/38—Seismology; Seismic or acoustic prospecting or detecting specially adapted for water-covered areas
    • G01V1/387—Reducing secondary bubble pulse, i.e. reducing the detected signals resulting from the generation and release of gas bubbles after the primary explosion

Definitions

  • This invention relates to a method of marine seismographic prospecting, and to explosive charges for use therein.
  • a method of seismographic prospecting for producing a record of underwater rock strata comprises generating a pressure wave by the firing underwater of an explosive charge having a length to diameter ratio exceeding 5:1 and recording the resulting seismic waves after reflection or refraction from underwater rock layer interfaces.
  • the length to diameter ratio is between l and 100:1 since such charges may contain suflicient charge per unit length to ates ac give a strong pressure wave whilst still being convenient to handle.
  • Heavy charges having a length to diameter ratio exceeding :1 are cumbersome to work with in prospecting conditions.
  • the charge distribution preferred is from 0.2 to 5 lb. per foot.
  • the invention also includes waterproof charges of detonatable explosive for use in underwater seismographic prospecting having a length to diameter ratio exceeding 5:1.
  • the explosive charge may be a unitary charge comprising explosive in a rigid container such as, for example, a tinplate canister or a tubular cardboard container, or the explosive charge may be contained in a flexible tube of, for example, synthetic thermoplastic which may be supplied in coiled form in bulk.
  • the explosive charge may be an assembly of spaced charges connected for substantially instantaneous initiation and assembled so that the overall length to diameter ratio of the assembled charge exceeds 5:1. It will be apparent that the smaller charges in the assembly may or may not have a length to diameter ratio exceeding 5:1.
  • the charges may, for example, be connected together for initiation by a line of detonating fuse-cord.
  • the invention further includes an apparatus assembly for seismic prospecting, com-prising an explosive charge of the invention located underwater and means for recording a seismic wave reflected or refracted from an underwater rock layer interface, consequently on detonation of the explosive charge.
  • the bubble pulse is much diminished in comparison to the bubble pulse obtained using the charges of the same weight and of the squat shape normally used, whereas the primary shock wave is not substantially different.
  • the bubble pulse suppression effect is more marked when the charges are orientated horizontally on firing.
  • FIG. 1 shows a diagrammatical longitudinal section of a canister primer cartridge
  • FIG. 2 shows a diagrammatical longitudinal section of a canister main-charge cartridge
  • FIG. 3 shows a diagrammatical longitudinal section of an elongated flexible cartridge assembly
  • FIG. 4 shows a bundled assembly of the cartridges shown in FIG. 3,
  • FIG. 5 is a sectional view on the line VV of FIG. 4,
  • FIG. 6 shows a spaced assembly of the cartridges shown in FIG. 3.
  • the canister primer cartridge shown in FIG. 1 has an elongated tubular tinplate body 11, sealed at one end with a recessed tinplate cap 12 which is formed with a pocket 13 to accommodate a detonator and at the other end with a tinplate cap 14 formed with an internal screw-threaded portion 15 adapted for attachment by screw engagement to a screw-ended canister cartridge of a less sensitive main explosive charge.
  • the cartridge is filled with a charge of powdered explosive consisting (by weight) of 88.5% of ammonium nitrate, 3.5% of anthracite and 8% of trinitro toluene.
  • the canister cartridge of main explosive charge shown in FIG. 2 has a tubular tinplate body 16 sealed with tinplate end caps 17, 18 formed respectively with matching male and female threads.
  • the cartridge is filled with a charge of powdered explosive consisting (by weight) of 92% of ammonium nitrate and 8% of trinitrotoluene.
  • the bodies of both cartridges are inches long and 2 inches in diameter.
  • the primer cartridge and optionally one or more cartridges of main charge attached thereto are immersed in the water over the area to be surveyed and fired by an electric detonator disposed in the detonator pocket 13.
  • the length to diameter ratio of the assembled charge may be varied at will by variation in the number of cartridges.
  • EXAMPLE 2 The explosive cartridge shown in FIG. 3 has an elongated tubular polyethylene body 19, 25 inches long and having an internal diameter of 0.625 in., and a wall thickness of 0.1 in. A polyethylene sleeve 20 is closely fitted over one end of the cartridge and this sleeve is used to attach a detonator or primer or to attach a further similar tubular charge to vary the length of the charge.
  • the cartridge is filled with an explosive charge which may, for example, have the composition of the primer or main charge given in Example 1.
  • EXAMPLE 3 In the assembly shown in FIG. 4, four of the cartridges 21 as shown in FIG. 3 are bundled together and held by strap 22. The explosive loading is thus readily varied by varying the number of cartridges in the bundle.
  • EXAMPLE 4 In the charge assembly shown in FIG. 6 a number of cartridges 23, as shown in FIG. 2, are spaced apart along a rope 24- and attached thereto by tapes 25. Detonators 26 are attached one to each cartridge by sleeves 27.
  • the cartridges shown in FIG. 1 may also be used in a spaced assembly wherein each cartridge is provided with a detonator.
  • the improvement comprising predetermining parameters for a suitable firing depth for an elongated condensed explosive charge having a length to maximum cross sectional dimension ratio exceeding 5:1, said predetermining step including selecting a depth at which a generalized shock wave will be utilized to provide energy from the shock pulse for directing the wave toward the rock strata and to control the bubble travel in a manner to prevent bubble breakthrough at the water surface, thereby providing substantially greater energy from the shock pulse than is provided under conditions where bubble breakthrough does occur; submerging the charge to at least said predetermined depth; and firing the charge, whereby undesired multiple pressure pulses of the type usually associated with explosion bubbles which do not break through the water surface are suppressed.
  • a method as claimed in claim 1 wherein the explosive charge comprises an assembly of spaced charges connected for substantially instantaneous initiation.

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  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Geology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Acoustics & Sound (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Oceanography (AREA)
  • General Engineering & Computer Science (AREA)
  • Geophysics And Detection Of Objects (AREA)
US691395A 1965-08-02 1967-12-18 Marine seismographic prospecting Expired - Lifetime US3500949A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB32934/65A GB1097420A (en) 1965-08-02 1965-08-02 Marine seismographic prospecting

Publications (1)

Publication Number Publication Date
US3500949A true US3500949A (en) 1970-03-17

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US691395A Expired - Lifetime US3500949A (en) 1965-08-02 1967-12-18 Marine seismographic prospecting

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US (1) US3500949A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE1548450B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
GB (1) GB1097420A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
NL (1) NL6610849A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4875545A (en) * 1985-02-20 1989-10-24 Pascouet Adrien P External bubble-suppression method and apparatus
US4949315A (en) * 1985-02-20 1990-08-14 Pascouet Adrien P External bubble-suppression method and apparatus

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3222765C2 (de) * 1982-06-18 1986-01-02 Comet GmbH Pyrotechnik - Apparatebau, 2850 Bremerhaven Behälter zur Lagerung und Abschuß - aus der Hand - einer Signalrakete
GB2132319B (en) * 1982-11-04 1986-10-29 Du Pont Canada Seismic explosive
GB2131924B (en) * 1982-11-04 1986-06-04 Du Pont Canada Explosives container kit

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2619186A (en) * 1948-01-24 1952-11-25 Standard Oil Dev Co Seismic exploration method
US2675882A (en) * 1949-11-12 1954-04-20 Sun Oil Co Seismographic prospecting
US2842056A (en) * 1954-05-04 1958-07-08 Seismograph Service Corp Explosive charge
US3009526A (en) * 1958-06-27 1961-11-21 Du Pont Seismic prospecting assembly
US3256501A (en) * 1960-06-06 1966-06-14 Shell Oil Co Seismic surveying system for water-covered areas
US3326126A (en) * 1964-02-15 1967-06-20 Dynamit Nobel Ag Explosive container

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2619186A (en) * 1948-01-24 1952-11-25 Standard Oil Dev Co Seismic exploration method
US2675882A (en) * 1949-11-12 1954-04-20 Sun Oil Co Seismographic prospecting
US2842056A (en) * 1954-05-04 1958-07-08 Seismograph Service Corp Explosive charge
US3009526A (en) * 1958-06-27 1961-11-21 Du Pont Seismic prospecting assembly
US3256501A (en) * 1960-06-06 1966-06-14 Shell Oil Co Seismic surveying system for water-covered areas
US3326126A (en) * 1964-02-15 1967-06-20 Dynamit Nobel Ag Explosive container

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4875545A (en) * 1985-02-20 1989-10-24 Pascouet Adrien P External bubble-suppression method and apparatus
US4949315A (en) * 1985-02-20 1990-08-14 Pascouet Adrien P External bubble-suppression method and apparatus

Also Published As

Publication number Publication date
NL6610849A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1967-02-03
DE1548450A1 (de) 1970-07-16
GB1097420A (en) 1968-01-03
DE1548450B2 (de) 1971-11-25

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