INTERFEROMETRIC REFRACTION STATICS FOR SEISMIC REFLECTION DATA FROM CHEONGJU GRANITIC BODIES OF KOREA

Refraction statics caused by rapid variations in the thickness of weathering layer are one of the critical problems during the processing step for land seismic reflection data. Long wavelength components of the statics tend to cause traveltime distortions in shot gathers, and thus yield an smeared stack response.

Conventional solutions to obtain the weathering model are usually solved by analysing first break of head wave assuming that shot and receiver points are located on a horizontal datum plane(Marsden, 1993; Cox, 1999; Yilmaz, 2001). However, first break picking method requires time consuming steps and causes the human error in picking the first arrivals, especially for low S/N land data. To overcome such problems, an interferometric approach(IRS: interferometric refraction statics)(Palmer, 2001; de Franco, 2005; Khatchatrian and Galbraith, 2013), which utilizes refraction convolution stack(RCS) and refraction velocity stack(RVS), is tested and applied to the seismic reflection data from Cheongju granitic bodies of Korea in this study.

IRS approach based on first arrival signal instead of first break time, is found to be much more effective in removing the statics of long wavelength components in stack section. In addition, continuities and resolution of the reflector are improved with more flattened event and the overlying refractors(the base of shallow weathering zone) are delineated in the refraction convolution stack.