Abstract: A technique facilitates determination of fracture attributes through the recording and analyzing of borehole sonic data before and after a fracturing operation. The technique comprises generating broadband acoustic waves at an array of receivers based on output from a plurality of acoustic sources. The waveforms of the broadband acoustic waves are recorded and processed to estimate sonic signatures. The sonic signatures are then used to determine fracture attributes. In some applications, the data may be used to determine whether the fractures in the formation are filled with fluid or soft sediments. Information on the fracture attributes is output to a suitable system, e.g. a computer display.

Abstract: According to an exemplary embodiment, an ultrasound apparatus for beamforming with a plane wave transmission may comprise a transceiver connected to a transducer array having at least one transducer element, and at least one processor. The transceiver transmits at least one substantially planar ultrasonic wave into a target region at one or more angles relative to the transducer array, and receives one or more signals responsive from the transducer array. The at least one processor applies a fast Fourier transform (FFT) to the one or more signals from each of the at least one transducer element and calculates at least one frequency within a frequency region, and applies an inverse FFT to at least one produced frequency data.

Abstract: A method is disclosed for calibration of a towed line array. In a low frequency band, calibration is performed using an acoustic field observed by reference standard hydrophones. The observations form a model of a complex acoustic field throughout a space occupied by a measurement apparatus. The array sensitivities are computed by comparing output voltages of the array with the acoustic field estimated at the locations occupied by hydrophones of the array. Variations in the acoustic field that cannot be accounted for by free field propagation theory are included in the calculation of array channel sensitivities. The method extends the low frequency limit for the calibration to less than the minimum frequency at which free field propagation conditions can be approximated. Boundary reflections and spatial variations in the acoustic field are recognized. The spatial distribution of acoustic energy is used to provide low frequency calibration with improved precision.