Almost all fractured mudstone reservoirs found both in and outside China are distributed in source rocks which are mainly composed of mudstones and shales

abundant in organic matter

calcareous and siliceous minerals. The abundance of organic carbon is 1.0%～20% in common with various types and their vitrinite reflectance is 0.5%～1.3%.There are three main genetic types of fractures which are structural

overpressured and diagenetic contraction ones in the source rocks. The mudstone reservoir caprocks are made up of non fractured mudstones

gypsum and halite rocks. Anticline and monocline are major trap types. The fractured mudstone reservoirs are believed to have great source potential due to a great deal of hydrocarbon remained in the source rocks.