Abstract:

Crack density is one of the important parameters which can be applied to the quantitative prediction of crackd reservoirs. Varela inverted crack density using SVD (singular value decomposition) method based on reflection coefficients various azimuth for HTI (horizontal transverse isotropy) media. We invert the crack density of HTI media by using SVD method based on difference of PP-wave AVA (amplitude variation with azimuth) data from crossing seismic survey lines. Anisotropy parameters play a more important role in the reflection coefficients difference. Firstly, the main principles of the two methods are described. Then the numerical computation was carried out and the inversion results of the two methods when reflection coefficients have random disturbances were contrasted. Finally, the stability analyses of the new improved method had made. The results show that the inversion results of both of these two methods are approaching to real value. However, the result of the improved method is better than that one of the old method, so the improved method has better anti-noise capabilities. The stability of this method goes better when the difference of azimuth increases. The influence caused by random disturbances is lowest when seismic survey lines are orthogonal intersection. The results can achieve a good stability when PP wave AVA data are with high signal to noise ratio.

Key words: crack density, amplitude variation with azimuth(AVA), singular value decomposition(SVD), HTI media