Method system of studying sequence stratigraphic framework of big sagged lacustrine basin: an example in Yanchang Formation of Mesozoic, Ordos Basin

Key words: 
• big sagged lacustrine basin /
• sequence stratigraphic framework /
• outcrop profile /
• relative lake level changes /
• wavelet analysis /
• borehole log /
• seismic profile /
• Yanchang Formation /
• Ordos Basin

Abstract: Abstract The study about sequence stratigraphy in big sagged lacustrine basin have made a quiet great progress, but the study about sequence stratigraphy in Ordos big sagged lacustrine basin have made less progress. The reasons as follow: the trait of seismic data on Loess Plateau is bad; the logging data may be interpreted variedly; contrast in isochronous is difficult; and right method system has not been found. In this paper, authors put forward a new method system of studying sequence stratigraphic framework of big sagged lacustrine basin which include six parts: establishing standard from outcrop profiles, confirming grade of sequence from wavelet analysis, ascertaining sequence cycles from lake level changes, affirming mode from borehole logs, notarizing framework from seismic interpretation, and proposing scheme from the integration of outcrop profiles, borehole logs and seismic interpreted profiles. This method system has been applied to the projects about petroleum prospecting of Ordos Mesozoic Basin. Finally, we have established the sequence stratigraphic framework which adapts to divide and contrast stratigraphy in Ordos Mesozoic basin.