Joakim Oscar Blanch

Direct wave arrivals are the most robust signals to determine velocity and consequently they have been used for almost a century in hydrocarbon exploration. The reason is simple as the arrivaltime is explicitly available and provide a direct measurement of the average velocity of the sub-surface ray-path. These signals have not been extensively used to estimate attenuation or Q. One reason may be that very few robust methods have been developed to estimate Q from these signals. The common method to estimate Q using data acquired from VSP measurements is relying on spectral ratios. This method is in general quite reliable whenever there is a signal that has a reasonably broad spectral support. I will show how a variation on the spectral ratio method that provides equal results while more robust and how it can be adapted for surface seismic measurement.