One Two
Wegweiser

Wegweiser MA 176

« April 2017 »
April
MoDiMiDoFrSaSo
12
3456789
10111213141516
17181920212223
24252627282930
Hauptkatalog

Wählen Sie Ihre Zweigstelle:

verantwortlich: ULB Bonn
 
Sie sind hier: Startseite Literatur Phase correction of electromagnetic coupling effects in cross-borehole EIT measurements

Y Zhao, Egon Zimmermann, Johan A Huisman, Andrea Treichel, Bernd Wolters, Stefan van Waasen, and Andreas Kemna (2015)

Phase correction of electromagnetic coupling effects in cross-borehole EIT measurements

Measurement Science and Technology, 26(1):11.

Borehole EIT measurements in a broad frequency range (mHz to kHz) are used to study subsurface geophysical properties. However, accurate measurements have long been difficult because the required long electric cables introduce undesired inductive and capacitive coupling effects. Recently, it has been shown that such effects can successfully be corrected in the case of single-borehole measurements. The aim of this paper is to extend the previously developed correction procedure for inductive coupling during EIT measurements in a single borehole to cross-borehole EIT measurements with multiple borehole electrode chains. In order to accelerate and simplify the previously developed correction procedure for inductive coupling, a pole–pole matrix of mutual inductances is defined. This consists of the inductances of each individual chain obtained from calibration measurements and the inductances between two chains calculated from the known cable positions using numerical modelling. The new correction procedure is successfully verified with measurements in a water-filled pool under controlled conditions where the errors introduced by capacitive coupling were well-defined and could be estimated by FEM forward modelling. In addition, EIT field measurements demonstrate that the correction methods increase the phase accuracy considerably. Overall, the phase accuracy of cross-hole EIT measurements after correction of inductive and capacitive coupling is improved to better than 1 mrad up to a frequency of 1 kHz, which substantially improves our ability to characterize the frequency-dependent complex electrical resistivity of weakly polarizable soils and sediments in situ.
Artikelaktionen