Abstract: A non-destructive method of measuring physical characteristics of a medium, such as uncemented sediment, sandstone, or limestone. A pseudo-random code is generated and is used to generate a pseudo-random acoustic signal. This signal is transmitted into the medium to be measured through the use of a transducer, such as a piezoelectric element, and is received by a plurality of hydrophones. The received signal is then processed to obtain an image of its velocity and attenuation. A universal geoacoustic model of the medium for a given set of measured data is determined, and the model is solved to obtain a pair of permeability-porosity results for the medium. The one of this pair of permeability-porosity results which is correctly indicative of the physical characteristics of the medium is then determined.

Abstract: On a source side, piezo-electric elements (34) are arranged such that vibration direction is perpendicular to a wall of a bore hole (12), and then an anvil (42) arranged on the piezo-electric elements in a bore hole wall side is pressure-contacted to the wall of the bore hole by a clamping mechanism (64). On a receiver side, upper and lower portion of another bore hole (112) are closed by a packer (182) and a shut-off valve (180), respectively, thereby preventing the fluid from flowing, and a cable (150) above a vibration receiver is fixed to the wall of said another bore hole (112) by a clamping mechanism (164), thereby reducing noise propagating through the cable. This increases measuring depth and crosswell distance of petroleum exploration and soil investigation by acoustic tomography, which causes applicability to be spread.

Abstract: A non-destructive method of measuring physical characteristics of a medium, such as uncemented sediment, sandstone, or limestone. A pseudo-random code is generated and is used to generate a pseudo-random acoustic signal. This signal is transmitted into the medium to be measured through the use of a transducer, such as a piezoelectric element, and is received by a plurality of hydrophones. The received signal is then processed to obtain an image of its velocity and attenuation. A universal geoacoustic model of the medium for a given set of measured data is determined, and the model is solved to obtain a pair of permeability-porosity results for the medium. The one of this pair of permeability-porosity results which is correctly indicative of the physical characteristics of the medium is then determined.

Abstract: An apparatus and method are provided for detecting buries objects, geological formations or sediment properties by transmitting an acoustic signal and receiving a scattered signal. An acoustic source and an array of receivers are used to correlate the scattered signal with the transmitted signal.

Abstract: A non-destructive method of measuring physical characteristics of sediments to obtain a cross-sectional distribution of porosity and permeability values and variations, and of shear modulus and shear strength. A pair of boreholes have borehole entries spaced apart from each other at a predetermined distance, and a plurality of hydrophones are spaced at predetermined known positions. A pseudo-random binary sequence code generator as a source of seismic energy is placed into another borehole and activated to transmit pseudo-random wave energy from the source to the hydrophones. Seismic wave characteristics are measured in a multiplicity of paths extending from the source to the hydrophones, using cross-bore tomography.

Abstract: A new method for measurement of the directional spectra of surface gravity (water) waves. Measurements are made at a single point by orthogonally mounted seismometers buried below the seabed surface and a pressure sensor resting on the seafloor or buried below the seabed. The maximum entropy principle is used to find the directional distribution function for the waves traveling through the sediments as measured by the seismometers. This function is combined with the frequency spectra of the ocean surface waves to form the directional spectra of the surface gravity waves. The method produced high directional resolution for instruments that were adequately coupled with the seabed. The method is also capable of detecting objects moving through water, such as surface ships and submarines.

Abstract: A non-destructive method of measuring physical characteristics of sediments to obtain a cross-sectional distribution of porosity and permeability values and variations, and of shear modulus and shear strength. A pair of boreholes have borehole entries spaced apart from each other at a predetermined distance, and a plurality of hydrophones are spaced at predetermined known positions. A source of seismic energy is placed into another borehole and activated to transmit seismic wave energy from the source to the hydrophones. Seismic wave characteristics are measured in a multiplicity of paths extending from the source to the hydrophones, using cross-bore hole tomography.

Abstract: A method of measuring the shear modulus profile of a seabed floor using one or more bottom shear modulus profilers, each having a seisometer package to measure the seabed motion in three dimensions and a sensor for measuring the pressure at the seabed floor, placed on or below the seabed floor, and a means for converting the measurements derived therefrom into a shear modulus profile.

Abstract: An apparatus for measuring the shear modulus profile of the seafloor by measuring the motion of the seafloor in three dimensions and the wave induced pressure at the seafloor and converting these measurements into a shear modulus profile using the Yamamoto equation and the linear inverse theory of wave-seabed interaction.