Michael K. Broadhead

Oscillating oil drops, resonant frequencies, and low-frequency passive seismology

A recent passive seismic technology in the oil industry, sometimes referred to as hydrocarbon microtremor analysis (also low-frequency spectroscopy), claims high correlation in some instances between the presence of hydrocarbons and low-frequency spectral anomalies (elevated spectral energy levels) computed from passively recorded seismic data. These observations have been reported for a number of different geographic locations. One of the difficulties in assessing this method is the lack of a physical basis for explaining the empirically observed effects. A potential explanation that has appeared in the literature can be referred to as the resonant amplification model. The main idea of the model is that, because of capillary effects, an oil drop in a rockpore will oscillate at a resonant frequency when driven by the ambient noise field of the earth. This resonance phenomenon is interpreted as a possible source of the spectral anomaly. I examined this model by numerical simulation but was unable to reprod...

The impact of random noise on seismic wavelet estimation

Deterministic seismic wavelet (or source signature) estimation is a mature subject, and is commonly accomplished by deconvolution using surface seismic amplitude data and borehole wireline log data. The seismic wavelet is important to reservoir geophysics/quantitative interpretation for use in inversion, synthetic seismograms, wavelet processing, etc. Hence, the quality of the wavelet estimate is of interest. Many factors affect wavelet uncertainty, including both seismic and well-log data quality, the latter which in turn affects the reflection coefficients estimate.

Using an isochron to constrain amplitude analysis: A case study of a carbonate stratigraphic trap in Saudi Arabia

A case study is presented which illustrates the benefit of including isochron analysis when analyzing amplitudes influenced by tuning. Since tuning influences the waveform, it also influences the isochron measured from a nearby event to the target. The model which explains the amplitude anomaly must also explain the isochron variation. The approach presented here is a fast and simple way to corroborate more sophisticated methods such as impedance inversion, and to compare the likelihood of various model scenarios.