Seismic 2D Reflection Processing and Interpretation of ... - Posiva

8Shot 1 Shot 2 Shot 3 Shot 4SPAirwaveFigure 4. Example of a noisy data set after removing the noisy traces, shot gather.First four shots from the line 34. AGC has been performed. Trace number on X-axisand two way travel time in seconds on Y-axis.2.2 Background informationThe processed and interpreted seismic results were compared and validated to set ofexisting knowledge on the site.The seismic velocities and signal frequency range have been investigated in precedingseismic VSP works (Enescu et al. 2004). Distribution of velocity data and velocityanomaly locations in boreholes have been extracted from borehole geophysicallogging, e.g. Julkunen et al. (2004), Lahti & Heikkinen (2005). Petrophysicalproperties of Olkiluoto lithology, and the elastic contrasts, were considered duringprior modelling by Mr. Tomas Lehtimäki (Saksa 2006, in preparation) for geometricalobservability, frequency range and attenuation; and by Dr. Christopher Juhlin inUppsala for considerations of, e.g., stacking fold and signal to noise ratio.Geometrical information on potentially reflecting bedrock features have been reviewedfrom bedrock model descriptions. These include features interpreted on basis ofhydrological model data (Ahokas & Vaittinen 2007), geological observations(Paulamäki et al. 2006), and interpretations based on multidisciplinary bedrockproperty classifications (Vaittinen et al. 2003). Results can be also directly comparedand reviewed against VSP and 3D seismic interpretations on the site (Enescu et al.2004, Juhlin & Cosma 2006).