A method of magnetotelluric exploration is described, wherein measures of the earth's electric and magnetic fields are obtained at a plurality of sensing locations comprising an areal array of sensing locations. Specifically, first and second components of the earth's electric field are measured at a plurality of sensing locations within an areal array of sensing locations whereby each of the components of the earth's electric field are spatially continuous. Additionally, first and second components of the earth's magnetic field are measured simultaneously at at least one location within the area covered by the areal arrays of sensing locations.
A method and apparatus for imaging deep underground objects utilizes the application of a spectral regularization routine that is applied to measured data prior to the application of an inversion routine to measured surface impedances to map subsurface conductivity. Specifically, measurement of magnetic and electric fields is conducted utilizing sensors at a measurement site, a processor is used to generate either resistivity or conductivity data based on the measurements of the sensors, the processor then performs the spectral regularization routine and an inversion routine to generate data that can be utilized to identify underground targets. The spectral regularization routine and inversion routine can either be processed separately (decoupled) or together. The measurements of the magnetic and electric fields are preferably made under the assumption of the presence of a plane wave at the measurement site.
A method of data acquisition for geophysical surveys. The method includes the steps of providing a least one magnetic sensor unit for sensing and recording magnetic field fluctuations; providing a plurality of electric sensor units for sensing and recording electric currents induced by the magnetic field fluctuations; receiving a satellite based timing signal and responsively synchronizing and bag a position for each of the plurality of electric sensor units and the at least one magnetic sensor unit; and synchronously recording the positions, the magnetic field fluctuations and the electric currents for downloading for processing.
A system for investigating subterranean strata. An electromagnetic field is applied using a fixed dipole antenna transmitter and this is detected using a dipole antenna receiver. The receiver is moved from one location to another in dependence upon the strength of the detected signal.
A method of processing an electromagnetic wavefield response in a seabed logging operation. The wavefield is resolved into upgoing and downgoing components. The downgoing component represents reflections from the sea surface while the upgoing component represents reflections and refractions from subterranean strata. The upgoing component is then subjected to analysis.
A method processing an electromagnetic wavefield response in a seabed logging operation. The wavefield is resolved into upgoing- and downgoing components. The downgoing component represents reflections from the sea surface while the upgoing component represents reflections and refractions from subterranean strata. The upgoing component is then subjected to analysis.
