Controlled-source interferometric redatuming by crosscorrelation and multidimensional deconvolution in elastic media

Various researchers have shown that accurate redatuming of controlled seismic sources to downhole receiver locations can be achieved without requiring a velocity model. By placing receivers in a horizontal or deviated well and turning them into virtual sources, accurate images can be obtained even below a complex near-subsurface. Examples...

Exploiting the airwave for time-lapse reservoir monitoring with CSEM on land

In the application of controlled source electromagnetics for reservoir monitoring on land, repeatability errors in the source will mask the time-lapse signal due to hydrocarbon production when recording surface data close to the source. We demonstrate that at larger distances, the airwave will still provide sufficient illumination of the target....

Laboratory measurements and theoretical modeling of seismoelectric interface response and coseismic wave fields

A full-waveform seismoelectric numerical model incorporating the directivity pattern of a pressure source is developed. This model provides predictions of coseismic electric fields and the electromagnetic waves that originate from a fluid/porous-medium interface. An experimental setup in which coseismic electric fields and interface responses...

Tutorial on seismic interferometry: Part 2 — Underlying theory and new advances

In the 1990s, the method of time-reversed acoustics was developed. This method exploits the fact that the acoustic wave equation for a lossless medium is invariant for time reversal. When ultrasonic responses recorded by piezoelectric transducers are reversed in time and fed simultaneously as source signals to the transducers, they focus at the...

Surface and borehole ground-penetrating-radar developments

During the past 80 years, ground-penetrating radar (GPR) has evolved from a skeptically received glacier sounder to a full multicomponent 3D volume-imaging and characterization device. The tool can be calibrated to allow for quantitative estimates of physical properties such as water content. Because of its high resolution, GPR is a valuable...

On seismic interferometry, the generalized optical theorem, and the scattering matrix of a point scatterer

We have analyzed the far-field approximation of the Green's function representation for seismic interferometry. By writing each of the Green's functions involved in the correlation process as a superposition of a direct wave and a scattered wave, the Green's function representation is rewritten as a superposition of four terms. When the...

Simultaneous measurement of hysteresis in capillary pressure and electric permittivity for multiphase flow through porous media

We present a tool that simultaneously measures the complex permittivity and the capillary pressure characteristics for multiphase flow. The sample holder is a parallel plate capacitor. A precision component analyzer is used to measure the impedance amplitude and phase angle as a function of frequency (1 kHz to 3 MHz). The complex impedance of...