On August 23, 2019 there was held a conference “Improvement and development technology of identifying the perspective objects based on frequency decomposition AVO – attributes”. The speaker was Feoksitova O.V. The theme of the report arose a great interest among specialist, the conferences generated lively discussion.
The low frequencies discovers the highest sensitivity to the fluid in a seismic-wave field.The effect had been demonstrated by several authors: Castagna, Ebrom, Chapman, Odebeatu in the 2000s.
In 2007 Goloshubin et al. got the results suggesting that there were differences in spectral data content that could be used to improve AVO identification (Figure 1).
These ideas created the prerequisites for searching ways of integration methods SD (spectral expansion) and AVO. Experimental studies were carried in INGEOSERVICE LLC on the Leningradskiy and Rusanovskiy fields according to the evidence in the intervals, following the confirmation of gas reserves that had been confirmed earlier by drilling (Figure 2).
The approach was based on the provision defining the relationship between amplitude of a signal and spectral peak based on the Fourier transform. The signal spectral peak analysis according to the frequency and distance allowed to determine the frequency range in which AVO effects are more reliable distinguished. Frequency interval determination allowing to take into account the divergence in near and far spreads of spectrums was carried out on the basis of diagrams and theirs distribution. The effectiveness of the selected line was frequency evaluated by «intercept-gradient» crossplots, time seismic sections and the attributes sections. The amplitudes brightness luminescence and the “intercept-gradient” range of values on the graphs and contour sharpness were compared. (Figur
e 3).
AVO improve technology efficiency through spectral expansion was revealed by pilot works that had been carried out on the Leningradskiy and Rusanovskiy fields. Further, The new technology was used as an additional for a more reliable classification of AVO effects on newly identified objects of the Karskomorskiy region.