Types and characteristics of the Ordovician carbonate reservoirs in Ordos Basin, China

In the Ordovician, the Ordos Basin was deposited in a two-uplift, two-saddles, two-depression paleotectonic framework. The two uplifts horizontally spread in an L shape and jointly controlled the Ordovician sedimentary facies as well as the regional distribution of different types of carbonate reservoirs. The Ordovician reservoirs were mainly divided into four types, i.e., weathering crust dissolution pore reservoirs, dolomite intercrystalline pore reservoirs, platform margin reef pore reservoirs, and karst-vuggy reservoirs. Of these, weathering crust dissolution pore reservoir is the most favorable reservoir, in which the large Jingbian gas field has been found. Initial breakthrough has been made in the exploration of dolomite intercrystalline pore reservoir. Substantial exploration progress has not been achieved in the other two types of reservoirs, but recent exploration has found some new signs of great exploration potential. These are the key frontiers of gas exploration in the Lower Paleozoic of Ordos Basin.