Q estimation using modified S transform based on pre-stack gathers and its applications on carbonate reservoir. (16th July 2015)

• Record Type: Journal Article
• Authors: Sun, Sam Zandong; Sun, Xuekai; Wang, Yonggang; Xie, Huiwen
• Is Part Of: Journal of geophysics and engineering. Volume 12:Number 5(2015:Oct.)
• Page Start: 725
• Page End: 733
• Publication Date: 2015-07-16
• Subjects: attenuation -- Q estimation -- modified S-transform -- inverse Q filtering -- dynamic Q migration -- carbonate reservoir -- secondary-storage-space; Geophysics -- Periodicals; Prospecting -- Geophysical methods -- Periodicals; Engineering -- Periodicals; 622.1505
• DOI: 10.1088/1742-2132/12/5/725
• Languages: English
• ISSNs: 1742-2132

Abstract

Abstract: Pre-stack seismic data is acknowledged to be more favorable in estimating Q values since it carries much more valuable information in traveltime and amplitude than post-stack data. However, the spectrum of reflectors can be strongly altered by nearby reflector or side lobes of the wavelet, which thereby degrades the accuracy of Q estimation based on the pre-stack spectral ratio method. To solve this problem, we propose a method based on the modified S -transform (MST) for estimating Q values from pre-stack gathers, in which Q values can be obtained with regression analysis based on the relationship between spectral ratio slope and the square of offset. Through tests on a numerical model, we first prove advantages of this pre-stack spectral ratio method compared to the traditional post-stack method. Besides, it is also shown that application of MST would lead to a much more focused intercept, which is the kernel for the pre-stack method. Therefore, the accuracy of Q estimation using MST is further improved when compared with that of conventional S -transform (ST). Based on this Q estimation method, we apply relevant processing methods (e.g. inverse Q filtering and dynamic Q migration) in practice, in order to improve imaging resolution and gathering quality with better amplitude and phase relationships. Applications on a carbonate reservoir witness remarkable enhancements of the imaging result, in which features of faults and deep strata are more clearly revealed. Moreover, pre-stack common-reflection-point (CRP) gathers obtained by dynamic Q migration well compensate the amplitude loss and correct the phase. Its ultimate pre-stack elastic inversion result better characterizes the geologic rules of complex carbonate reservoir predominated by secondary-storage-space.