Oil and gas are concentrated in Yaka-Yengimahalla Area in Tabei Uplift, where the Cambrian-Ordovician carbonate reservoirs have been before taken for weathering crust of buried paleohill in exploration attempt. Recent fine description of reservoirs reveals that there are other types of reservoirs such as exposed shoal, interbedded paleo-karst and dolostone reservoirs. The weathering-reformed dolostone reservoir beneath buried paleohill surface is best expectant to exploration success, and the exposed shoal reservoir is next. The exposed shoal reservoir can be classified into the remnant one of early hydrocarbon accumulation and the one of late hydrocarbon accumulation. The primary reservoir of early hydrocarbon accumulation is irrelative with the buried paleohill in this area. The weathering crust reservoir of buried paleohill may be late accumulated but the producing test shows it is an aquifer.