Determination of the sequence stratigraphy boundaries by combining the wavelet analysis of wire line data - case study in South Pars field

Nowadays, wavelet analysis has many applications to identify and analyze the transient boundaries and waves, such as image borders and earthquake waves. Detection of discontinuities in the sedimentary sequences and identifying the boundaries of sequence stratigraphic surfaces are one of those applications. In this study, wavelet analysis was used to analyze wirline logs data, such as GR, NPHI, RHOB, RHOZ, THOR / URAN and multimin data such as anhydrite percentage volume, in which the data vary in sequence boundaries. Different types of sequence boundaries impact on different types of logs. The wireline logs are affected by structural and lithological changes; thus, we cannot identify those boundaries using a kind of correlation coefficients. In this study, a combination of coefficients for the wireline logs is used. This combination offers a good way to automatically determine the borders fairly accurate. The best results are obtained from the coefficients combination of GR, NPHI, RHOB (RHOZ) logs and the anhydrite percentage volume multimin, and also, the coefficients combination of GR, NPHI, RHOB (RHOZ) logs and thorium to uranium ratio (THOR / URAN) graphs. Comparison between the results of this study in Kangan and Dalan formations of South Pars gas field with the other proved methods show the capability of this technique in combination of data.