Effects of Triassic Yanchang Slope Break on Lithologic Reservior in Ordos Basin

The study on the sequence stratigraphy of Yanchang formation of Triassic in Ordos basin shows that there exist sedimentary slope break in margin of ramp belt of the basin.The slope break assumes NW-SE trending distribution.The slope break in the north is narrow and steep,toward the east,it becomes broad and gentle.This paper discusses the effects of the sedimentary slope break on the lithologic reservoir in Ordos basin in three aspects: 1)the control of the sand combination type,distribution and physical properties of the reservoir;2)the control of the spatial distribution of the blocking stratum-flooding stratum,and 3)the control of the oil-gas migration directions and gathering spaces.