Mostafa Ebrahimi - Geophysics Institute of Tehran University, Tehran, Iran
Ali Moradi - Geophysics Institute of Tehran University, Tehran, Iran

Nowadays, the researches in passive seismic methods indicate presence of low frequency (1-6 Hz) signals upon hydrocarbon reservoirs. Based on obtained desirable results, Analysis of this characteristic spectral anomaly has been used as a technique to provide information about the presence of hydrocarbon reservoir or Direct Hydrocarbon Indicator (DHT). Thus, DHI passive seismic method can be used as for pre-eliminary survey and well placement for field appraisal and development. The method is passive in the sense that it does not require man-made seismic sources. The observations on low frequency band of microtremors are used to calculate the spectral ratio of vertical and horizontal components (V/H) and polarization.vertical and horizontal components (V/H) and polarization are calculated and a sharp spectrum anomaly is shown in frequency of 2-4Hz in top of the reservoir (station 5).

passive seismic, low frequency, hydrocarbon reservoirs, DHI, VH, polarization