Revealing the accumulation patterns of Chang 1 oil reservoir of the Yangchang Formation in Ordos Basin is very significant for oil and gas exploration in this area.Based on stratigraphic division and correlation

the paleogeomorphology of Chang 1 oil reservoir is restored by using residual thickness methods combined with previous research of regional paleogeomorphology.On this basis

its relationship with the distribution of hydrocarbons is analyzed.The patterns of hydrocarbon accumulation of this formation in this region are summarized through a comprehensive analysis of various controlling factors on hydrocarbon accumulation such as structures

sedimentary facies

sandstone thickness

sealing conditions

and so on.Three geomorphic units are recognized in Chang 1 oil reservoir

namely erosion valley

erosion slope and erosion monadnock.The paleogeomorphology features in "one valley

two slopes and two monadnocks".The erosion monadnocks in relatively higher terrain

the ridges of nose-like uplift

channel sands with larger thickness and higher net-to-gross ratio all have significant controlling effects on distribution of hydrocarbons of this formation.Moreover

cyclical mudstone

tight sandstone

erosion unconformity surfaces and hydrodynamic force all have large contributions to the sealing of the Chang 1 oil reservoir.Structural-lithologic reservoir and lithologic reservoir are the primary reservoir types

while lithologic-hydrodynamic reservoir is the secondary reservoir type.The overlapping regions of the main factors

such as the higher paleogeomorphology and the favorable sedimentary facies zones with larger sandstone thickness are the key exploration targets of this formation in Ordos Basin.