Interpretation Of Seismic Tomography Results Using Data Quality And Residual Error Maps

In seismic borehole tomography, the interpretation of the results is commonly limited to the comparison of the velocity map, the ray coverage, and the global root mean square RMS residual. However, the quality of the seismic data has a significant influence on the accuracy of the arrival time picking but is generally not considered in the inversion. This paper presents an enhancement of the inversion taking into account the data quality, based on the signal-to-noise ratio, by using it to weight the travel time residuals in each iteration step. This implementation also calculates the spatial distribution of the data quality and the distribution of the residual remaining at the end of the inversion, which are used to support the evaluation of a velocity map. The effect of the data weighting is studied on a field data set. Quality and residual maps are given and their relevance for the interpretation is discussed. The results indicate that areas of exceptionally high signal attenuation can be identified by means of the quality information.