Application of High Definition Seismic technology in severe nearsurface seismogeologic surroundings

Complex near surface conditions sometimes provide unacceptable challenge to traditional seismic processing. This kind of conditions may take place for example if high level of noises is combined with high amplitude variations of velocities in the upper part of section. This may be often met in permafrost areas with thawing zones and in mountain areas. Two main specific procedures from High Definition Seismic (HDS) technology are applied to fit these challenges. One is iterative wave field analysis instead of usually applied detection of signals among noises and the other is “Polycor” static correction method with high resistance to noises. The examples are shown for low frequency static shifts for mountain relief and midi frequency static shifts for thawing zones in permafrost surroundings. In the first case static shifts with period of 2O km were determined and in the second one amplitude of static shifts with period of about 0.5 km was about 60 ms. As the results of wave field analysis with iterative adjustment of different types of noises and useful signals reliable reflections were detected in original seismograms with high level of noises and high amplitude midi frequency static shifts were reliably determined. Coherent velocity analysis showed that signal to noise ration was increased more than ten times. The HDS section obtained compared to traditional processing technology showed better correlation of reflection boundaries in full time range, reliable structural positioning of productive well and reasonable positioning of projected well.