Comparison of tectonic evolutions and petroleum geological conditions between Tazhong and Tabei palaeohighs shows that

in Middle Caledonian

Tazhong area was uplifted

resulting in the absence of Middle Ordovician and well developed weathered residuum and karst

while the Upper Ordovician source rock and reef flat reservoirs facies were limited on the palaeohigh. Tabei area was then still in a platform-slope environment

Upper and Middle Ordovician were relatively complete

lime-mud mound source rocks of platform edge facies were widely distributed

and karst reservoirs on the unconformable surface in the Middle Ordovician sequence of reef flat facies were well developed. In Middle-Late Caledonian

3 anticlinal structural belts were developed in Tazhong area due to strong movement

and weathered residuum and karst were developed only in carbonate outcrops on top of the anticlines. Whereas Tabei area was overall uplifted

then weathered residuum and karst were undeveloped

because carbonates had not been cropping out. In Late Caledonian

large amount of hydrocarbons accumulated in Tazhong area

since the palaeohigh had been formed; while only sporadic charging of hydrocarbons occurred in Tabei area. In Early Hercynian

the eastern part of Tazhong area was relatively elevated

leading to the palaeohigh to have a topography of high in the east and low in the west. The Donghe Formation sandstone was deposited in the west-central part

while multiple small residuum-karst reservoirs were developed in the eastern buried hill zone. Tabei area was strongly uplifted

and carbonates in the nose structure had wholly been cropped out

resulting in the development of large residuum-karst system. After Early Hercynian

Tazhong palaeohigh became a residual palaeohigh along with elevation and subsidence of the basin

and the topography of high in the east and low in the west made it possible to collect and accumulate hydrocarbons in Awati sag through fracture belt Ⅰ. The strong and continuous uplifting of Tabei area made it to be an inherited palaeohigh and became the major directed area of hydrocarbons mirgration from Manjiar sag.Considering the situation the mentioned above

it is suggested that the petroleum exploration in Tabei area can be extended to the southern slope

while that in Tazhong area can be extended to the western slope

and the explortion in the southeast periphery area should be target at the Late Caledonian fossil oil accumulations.