Communications – electrical: acoustic wave systems and devices – Seismic prospecting
Patent
1986-04-11
1987-09-08
Kyle, Deborah L.
Communications, electrical: acoustic wave systems and devices
Seismic prospecting
181108, 324323, G01V 300
Patent
active
046929053
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to geophysical methods of prospecting mineral deposits, using seismic prospecting and radio-wave prospecting and is particularly concerned with a method for geophysical prospecting of complex or polymetallic orebodies.
PRIOR ART
The spatial distribution of complex orebodies within the rock mass is fairly complicated. To be suitable for industrial exploitation, the thickness of an orebody should comply to various criteria, including the value of the mineral or mineral complex. Sometimes, even centimeter-thick orebodies are worth exploiting, while in other mining conditions the minimum thickness of orebodies whose exploitation is economically profitable exceeds tens or even hundreds of centimeters. It is important, therefore, that geophysical prospecting concentrates to define the thickness of orebodies.
Traditionally, the thickness of complex orebodies was the subject of geological methods, such as exploratory workings, drilling a series of prospecting holes to obtain cores whose composition is indicative of the thickness of the orebody cut by the hole. The usual distance between holes is about 20 meters. This method is obviously labour-intensive, lengthy and costly, but nevertheless insufficiently effective. With an elaborate configuration of some orebodies, some holes may pass in constrictions of such orebodies resulting in poor correlation of the data obtained in two adjacent holes.
Some geophysical methods can be used to produce orebody thickness estimates without hole drilling or exploratory workings. Based on the known phenomena of piezoelectric polarization of the rocks which are piezoelectrics, is a method for piezoelectric prospecting of quartz-bearing orebodies. The use of this method permits determination of the quartz vein thickness by the duration of the electromagnetic pulse generated by the quartz-bearing orebody when it is excited by an elastic wave/cf., for example, G. A. Sobolev, V. M. Demin, Mechano-Electric Fenomena in Earth, published in 1980 by Nauka Publ., p. 91, in Russian/.
But this method is unsuitable for determination of the thickness of complex orebodies having insignificant amounts of piezoelectric minerals, such as quartz or sphalerite, or having no piezoelectric minerals at all, since polymetallic orebodies generate no electromagnetic radiation based on piezoelectric phenomena. To conclude, it can be said that the known method cannot be used for prospecting the majority of polymetallic deposits in the USSR and other countries.
Also known in the art is a method for geophysical prospecting of complex or polymetallic orebodies having no piezoelectric effect, which consists in that elastic waves are excited in the rock mass containing orebodies at least twice, and then the arrival time of the first pulse of each pulse train of the radio-frequency radiation which is generated by the orebodies, the number of pulse trains during one excitation period being equal to the number of orebodies (cf., Inventor's Certificate No. 972 453, filed Mar. 4, 1981, published Nov. 7, 1982, in the bulletin "Discoveries, Inventions, Industrial Designs and Trademarks", No. 41, IPC.sup.3 G 01V 11/00). This method permits determination of the existance of an orebody having no piezoelectric properties, and is based on the comparison of the duration and amplitudes of electromagnetic signals in the low frequency and high frequency ranges.
But this method cannot be used to define the thickness of complex orebodies.
DISCLOSURE OF THE INVENTION
It is an object of the invention to provide a method for geophysical prospecting of polymetallic or complex orebodies, which can be used to determine the thickness of complex orebodies deposited in the rock mass.
This object is achieved by that in a method for geophysical prospecting of complex orebodies, consisting in that elastic waves are excited at least twice in the rock mass containing orebodies, the arrival time of the first pulse in each train of pulses of electromagnetic radiorange radiation generated by oreb
REFERENCES:
patent: 3524129 (1970-08-01), Ikrath
patent: 3621380 (1971-11-01), Barlow, Jr.
S. N. Kondrashev, "Piezoelectric Methods of Prospecting", Nedra Publishing ouse, Moscow 1980, pp. 37-39.
"Electrical and Mechanical Properties of Rocks Under High Pressure" USSR Academy of Science Transactions of the Institute of the Earth Physics, No. 37 (204), Nauks Publishing House, Moscow 1966, pp. 221-227.
Sobolev et al, "Electromechanical Phenomena in the Earth", USSR Academy of Science Institute Fiziki Zemli, Nauka Publishing House, Moscow 1980, pp. 91-97.
Demin Vladislav M.
Los Vladimir F.
Maibuk Zinovy-Jury Y.
Sobolev Gennady A.
Griffiths John E.
Institut Fiziki Zemli Imeni O.Ju. Shmidta Akademii Nauk SSSR
Kyle Deborah L.
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