Estimation of seismic attenuation for reservoirs mapping and inverse Q-filtering: An application on land seismic data

Seismic attenuation values based on inverse Q-filtering are useful in enhancing seismic data resolution for quantitative interpretation. However, as field attenuation estimations are often contaminated by noise and overburden effects, an inverse Q-filter may reduce the signal-to-noise ratio. To help reservoir mapping with seismic resolution enhancement, we use well logs and surface seismic data to estimate the attenuation of a depth interval composed of several carbonate oil reservoirs onshore the Arabian Peninsula. From applying a prestack Q inversion on tau-p gathers from a large 3D seismic survey, the estimated effective attenuation values show spatially coherent patterns, likely corresponding to changes in the petrophysical and fluid properties. The patterns of the estimated effective attenuation values correlate considerably with the anticline geometry, with higher values on its crest than its flanks. The small percentage of the negative effective attenuation values indicates that the apparent attenuation and overburden effects are insignificant. At well locations, the effective attenuation values show a good correlation with the average porosity of the main reservoir, verifying that they are related to changes in petrophysical properties in the analysis interval. We propose an extended inverse Q-filter with two additional parameters to make it more robust and flexible and test it with synthetic and field datasets. We estimate a multiple-scattering attenuation value from well logs and use it in the proposed filter for the field dataset. The compensation for the multiple-scattering effects suppresses the overprints of the data components unrelated to the target interval, hence benefitting the quantitative data interpretation.