Abstract
Acoustic crosswell tomography was used for determining the sediment porosity, permeability, and shear strength from travel-time measurements by means of travel-time inversion and rock mechanics [Yamamoto etal., Geophysics (1994) (1995)]. These properties can be used to model the propagation and scattering of acoustic waves in saturated sediments. Due to the effects of intrinsic attenuation, transmission loss, and scattering, crosswell measurements usually are limited to ranges of 50–100 times the wavelength of the signals. It was believed that the diffusive nature of scattering put the coherent limit of acoustic wave propagation in sediments at approximately 1000 wavelengths. To extend the measurements of the propagation of acoustic waves to longer ranges, a real time processing and data acquisition system was employed. A crosswell tomography experiment with a crosswell distance of 540 m was performed at a limestone aquifer at Sanibel Island, Florida. Pseudorandom binary sequences modulated with carrier frequencies up to 6 kHz, which puts the range around 1400 wavelengths, were successfully transmitted by using pulse compression and coherent averaging techniques. The hydraulic structure of the Earth with a cross section of 540 m×150 m has been imaged at spatial resolution of a few meters. [Work supported by ONR.]
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
