Electrical and Computer Engineering
Department of Electrical and Computer EngineeringUniversity of Illinois Urbana-Champaign


Current distribution cAlculations

Antenna design and simulations

Sensor modeling

RCS & Bi-RCS computations

Current distributions on metallic plates

Inverse scattering simulations

Radargrams of buried pipes

Experimental inverse scattering

Borehole measurements





Experimental Borehole Measurements

The following results show different aspects of the response of experimental logging tools used for petrol extraction. These tests are performed with a known underground profile of resistivity which is included in all the Figures. The two measurement tools used are Schlumberger's 6FF40 and Halliburton's HRI.

The following Figure shows so-called anticorrelation phenomenon. The changes of the apparent conductivity (given by the tool as an output) is anticorrelated with the true conductivity. The reason is that the beds are so thin that their main frequency components are located in the negative part of the transfer function of the 6FF40 tool. By using the High Resolution Induction tool (HRI), this phenomenon can be eliminated.

Anticorrelation phenomenon

The next Figure shows the resolution capacity of both 6FF40 and HRI tools using a "chirp" model for the underground profile of resistivity.


The following figure shows the "blind frequencies" of the 6FF40 tool. The main frequency components are very close to the first zero of the 6FF40's transfer function. Therefore, the 6FF40 cannot detect the existence of these thin beds. By using the HRI tool, these beds can be detected.

Blind frequencies of the 6FF40 tool

The final Figure shows the 6FF40 response in the Oklahoma benchmark, a famous an well-known underground profile. The change of the apparent conductivity at different dipping angles is caused by the "dipping effect".

Dipping effect

The above work is a collaboration between Siyuan Chen and Prof. Weng Cho Chew. Please send suggestions, comments, and inquiries to: siyuan@espark.ece.uiuc.edu.