Hydrocarbon reservoirs and their controlling factors in the lower associations of the middle part of southern Junggar Basin, Xinjiang

The lower entrapments in the middle part of southern Junggar Basin, Xinjiang has been less explored for a long time. The excellent conditions for hydrocarbon accumulation in this area have proven to be the favourable risk exploration area. These entrapments tend to be hosted in the Jurassic and Lower Cretaceous strata. The present paper discusses the hydrocarbon reservoirs and their controlling factors in the Lower Cretaceous Qingshuihe Formation, Upper Jurassic Kalazha and Qigu Formations. The hydrocarbon reservoirs in the study area are mostly made up of feldspathic lithic sandstone and lithic arkose which are characterized by low compositional maturity, low to moderate and moderate to high textural maturity, and pervasive calcite and analcite. The main controlling factors influencing the reservoir potential include the contents of the fillings and lithology (grain size). The compaction and cementation are responsible for the loss of the primary porosity.