Study on the Anisotropy of Formation Resistivity by Dual Controlled-source Electromagnetic Sounding

Abstract

We proposed a method to obtain the anisotropy of formation resistivity by dual controlled-source electromagnetic sounding. The two field sources are arranged in two orthogonal directions outside the measuring area: the two grounded dipole sources excite two uncorrelated signals current step by step alternately, and record the current into time series; At sounding station of survey area, the orthogonal horizontal electric field response signals or the vertical magnetic field response signals were recorded into time series; according to the recorded current time series, As well as the time series of electromagnetic response signal, and the parameters of working layouts such as transceiver distance and so on, the whole zone apparent resistivity of the sounding station were calculated by circular cross-correlation system identification method, and then the anisotropy coefficient of the formation resistivity was calculated according to the whole zone apparent resistivity. This method has the advantages of fewer observation components, simple processing, strong anti-interference ability, and high working efficiency.