Acoustic sounding instrument

Claim 2

An acoustic sounding instrument for determining acoustical characteristics of the earth surrounding a borehole, comprising: at least one acoustic emitter and at least one acoustic reciever spaced with respect to each other, said emitter including an active transducer element emitting acoustic signals principally radially from a curved, essentially cylindrical surface of revolution, and said receiver including an actice transducer element receiving the acoustic signals principally radially at a curved, essentially cylindrical surface of revolution, said emitting cylindrical surface and said receiving cylindrical surface being positioned with the mean cross-sectional planes thereof disposed essentially in the same longitudinal plane of said sounding instrument, wherein said emitter and said receiver each are enclosed in a cover made from a material capable of substantially absorbing the acoustic waves, said cover having at least one opening for the passage of the useful acoustic rays to said active transducer elements.

Claim 3

An acoustic sounding instrument for determining acoustical characteristics of the earth surrounding a borehole comprising: at least one acoustic emitter and at least one acoustic receiver spaced with respect to each other, said emitter including an active transducer element emitting acoustic signals principally radially from a curved, essentially cylindrical surface of revolution, and said receiver including an active transducer element receiving the acoustic signals principally radially at a curved, essentially cylindrical surface of revolution, said emitting cylindrical surface and said receiving cylindrical surface being positioned with the mean cross-sectional planes thereof disposed essentially in the same longitudinal plane of the sounding instrument, wherein said acoustic emitter comprises three emitters at a first level of said sounding instrument, and said acoustic receiver comprises three receivers at a second level of said sounding instrument, the mean cross-sectional pleanse of respective emitters and receivers being disposed essentially in three planes forming therebetween angles of 120*.

Claim 4

An acoustic sounding instrument for determining acoustical characteristics of the earth surrounding a borehole comprising: at least one acoustic emitter and at least one acoustic receiver spaced with respect to each other, said emitter including an active transducer element emitting acoustic signals principally radially from a curved, essentially cylindrical surface of revolution, and said receiver including an active transducer element receiving the acoustic signals principally radially at a curved, essentially cylindrical surface of revolution, said emitting cylindrical surface and said receiving cylindrical surface being positioned with the mean cross-sectional planes thereof disposed essentially in the same longitudinal plane of the sounding instrument, wherein said acoustic emitter comprises three emitters at a first level of said sounding instrument, and said acoustic receiver comprises three receivers at a second level of said sounding instrument, the mean cross-sectional pleanse of respective emitters and receivers being disposed essentially in three planes forming therebetween angles of 120*.

Claim 5

An acoustic sounding instrument for determining acoustical characteristics of the earth surrounding a borehole comprising: at least one acoustic emitter and at least one acoustic receiver spaced with respect to each other, said emitter including an active transducer element emitting acoustic signals principally radially from a curved, essentially cylindrical surface of revolution, and said receiver including an active transducer element receiving the acoustic signals principally radially at a curved, essentially cylindrical surface of revolution, said emitting cylindrical surface and said receiving cylindrical surface being positioned with the mean cross-sectional planes thereof disposed essentially in the same longtiudinal plane of the sounding instrument, wherein said emitter and said receiver each are enclosed in a cover made from a material capable of substantially absorbing the acoustic waves, each cover having at least one opening for the passage of useful acoustic rays to said active transducer elements, and wherein the active element of said emitter and that of said receiver are constituted of a cylindrical ring secured axially between two circular plate means capable of substantially absorbing the acoustic waves and a pair of fluid-tight annular seals disposed respectively between the cylindrical ring and each of said plate means.

Claim 6

An acoustic sounding instrument for determining acoustical characteristics of the earth surrounding a borehole comprising: at least one acoustic emitter and at least one acoustic receiver spaced with respect to each other, said emitter including an active transducer element emitting acoustic signals principally radially from a curved, essentially cylindrical surface of revolution, and said receiver including an active transducer element receiving the acoustic signals principally radially at a curved, essentially cylindrical surface of revolution, said emitting cylindrical surface and said receiving cylindrical surface being positioned with the mean cross-sectional planes thereof disposed essentially in the same longtiudinal plane of the sounding instrument, wherein said emitter and said receiver each are enclosed in a cover made from a material capable of substantially absorbing the acoustic waves, each cover having at least one opening for the passage of useful acoustic rays to said active transducer elements, and wherein the active element of said emitter and that of said receiver are constituted of a cylindrical ring secured axially between two circular plate means capable of substantially absorbing the acoustic waves and a pair of fluid-tight annular seals disposed respectively between the cylindrical ring and each of said plate means.

Claim 7

An acoustic sounding instrument according to claim 3, wherein the inner space delimited by said ring and by said plate means is filled with an electrical insulating liquid, and in that at least one equalizing membrane disposed in at least one of said plates assures equality of hydrostatic pressure in the borehole and the pRessure of said insulating liquid inside said transducer.