High quality source rocks in the Upper Ordovician and the Lower Silurian in southern China are mainly developed in the Wufeng Formation of the Upper Ordovician and at the bottom of the Lower Silurian.Both the Silurian elastic reservoirs and carbonate reservoirs feature in low-and ultra-low porosity and permeability and the former is the predominant reservoir type.The Lower Silurian Longrnaxi Formation is a set of quality regional seal and is in the B to late stage of diagenesis as a whole.Although being at high level of evolution

they serve as good sealing for petroleum accumulations.The eastern Sichuan basin of the Upper Yangtze Platform had witnessed large-scale hydrocarbon generation in a relatively early time with most of the Silurian source rocks reaching hydrocarbon generation peak during the middle Jurassic;while most of the Silurian source rocks in the Middle Yangtze Platform entered hydrocarbon generation peak late in the Late Triassic.The hydrocarbon migration and accumulation during the Silurian were controlled by Paleo-tectonic evolution.Therefore

it is suggested that the southwestern Sichuan provinces

western Hubei Province

and eastern Chongqing municipality are the most favorable areas for exploration of Silurian gas

while the thrust-fold area in the southern Jianghan plain is the favorable area.