Application Of Wavelet Transform In Studies Of Sequence Stratigraphy Of K₁y₄of Xingcheng

Xingcheng is the main gas reservoir of Xujiaweizi fault subsidence. With largestratigraphic thickness of K1y4which contains overall gas and has good exploration potential,K1y4is an important exploration area and the key area. The thickness of sediments of K1y4isnearly200m, and it is a relatively homogeneous layer of thick sedimentary conglomerate,which is not obvious on conventional logging curves. Because the seismic reflection axis ismostly the single strong reflection and the coring well data is poor, how to divide its internalsequence is the key research of the K1y4. Combining the previous research results, this paperfirst analyzes the geology of Xingcheng, which fully understands the characteristics ofsedimentary strata. It has a whole basic understanding of the entire study area.The natural gamma curve has a relationship with the shale content of the formation, whichcan reflect the changes of the sediments. The wavelet transform is a hotspot in recent years,which is a breakthrough in Fourier transform and has been widely used in science andengineering disciplines. Based on the time-frequency characteristics of wavelet analysis andmulti-scale analysis, this paper researches the sequence stratigraphic division by usingdifferent scale factor of wavelet coefficient curves of different level sequence division. TheK1y4in Xingcheng is divided into2tri-term base-level cycles coupled with other logging data,coring data to identify and divide the sequence interface. Since the deposition of the lower ofthe K1y4is mainly the mudstone, and the lower has the poor gas containing, it no longerdivides the whole of K1y4, instead, only divides the upper of the internal K1y4. First the paperdivides the upper of the K1y4into three four-term base-level cycles and then combines withsystem domain to establish the stratigraphic framework which is applicable to this study areafor stratigraphic correlation according to the geologic features of the local region. It willprovide a feasible method for internal sequence research of thick conglomerate.By analyzing the development controlling factors of K1y4conglomerate reservoir, thepaper forecasts the favorable sequence and its vertical distribution range in the study area.