System for plotting subsoil structure and method therefor

US4214226A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• Keshavaiyengar Y. Narasimhan · Tecate Mission Road, US
• Robert Nathan · Atlanta, US
• Shakkottai P. Parthasarathy · Burbank, US

Key dates

• Filing date: Sep 6, 1977
• Grant date: Jul 22, 1980
• Expiry date: Sep 6, 1997

Classification

• Technology area (CPC G): Physics
• CPC primary: G01V1/42
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Data for use in producing a tomograph of subsoil structure between boreholes is derived by placing spaced geophones in one borehole, and if desired also on the earth surface, and by producing a sequence of shots at spaced apart locations in the other borehole. The signals, detected by each of the geophones from the various shots, are processed either on a time of arrival basis, or on the basis of signal amplitude, to provide information of the characteristics of a large number of incremental areas (pixels) between the boreholes. Such information is useable to produce a tomograph of the subsoil structure between the boreholes. By processing signals of relatively high frequencies, e.g., up to 1000 Hz, and by closely spacing the geophones, a high resolution tomograph can be produced.