Following reservoirs of Lower Paleozoic in South Ordos are prospective for oil and gas exploration:dolomite intercrystalline pore reservoir of Middle Cambrian Zhangxia Formation;dolomite corroded pore and vug reservoir of tidal flat facies of Lower Ordovician Liangjiashan Formation;gypsum cast corroded pore and vug reservoir of supratidal flat facies of the 3rd and 5th Members of Lower Ordovician Majiagou Formation;the interlayer karst weathered crust karst reservoirs of the 2nd～4th Members of the Upper Majiagou Formation;dolomite reservoirs of marginal reef bank complex of Middle Ordovician Pingliang Jinghe Formations.The shale and coal series of Upper Paleozoic Benxi～Taiyuan～Shanxi Formations serve as regional cap rocks.Five reservoir cap rock complexes have been recognized

and within the seven prospecting target blocks in South Ordos

the first and second blocks have the best reservoir cap rock assemblages.