Sequence Stratigraphy Analysis of High Frequency for Reservoir of Changqing Gas Field
WANG Hong-gang 1, LU Bing-quan 1, SUN Xiao-gang 2 (1.Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China; 2.Shanghai Geotechnical Investigation and Design Institute, Shanghai 200092, China)
The main reservoir of Changqing Gas Field in Ordos Basin is M 5 1 of upper Majiagou Formation, which belongs to marine deposits of evaporating marginal sea and is composed of oolite dolomite, graindolomite, algal dolomite, pelitic dolomite, gypsodolomite, gypsiferous dolostone, etc. The high pelitic dolostone, dolomitic pelite and slightly dolomitic pelite represent flooding deposits characterized by stable lithofacies and extensive distribution and usually regarded as reference lamina. The spectrum chart and its main frequency series are obtained by utilizing Fast Fourier Tansformation (FFT) to natural gamma logging curves. The ratio of chief-frequency wave length is identical with that of the eccentricity cycle and the tilting cycle, inferring that the high-frequency sedimentary sequence of M 5 1 corresponds to Milankovitch Cycle. It is, therefore, reasonable to deduce the sequence cycle of high frequency of the Reservoir M 5 1 is caused by astronomical factors.
【CateGory Index】： P534