Reservoir characteristics and controlling factors of Paleogene in Qianxi area in northern margin of Qaidam Basin

Based on the drilling, logging data and core test analysis, it is concluded that the reservoir component of Paleogene in Qianxi area mainly are lithic arkose and feldspathic litharenite with low maturity, and the reservoir spaces mainly are secondary dissolved pore including intergranular dissolved pore, intragranular dissolved pore and casting pore. The average porosity of the reservoir is 10.1%, and the average permeability is 21.64 mD. The Paleogene reservoir is low porosity and low permeability reservoir with strong heterogeneity. The reservoir is influenced by sedimentary facies and diagenesis. Sedimentary facies plays a role in macro control of the reservoir development, and the reservoir developed in braided channel has relative good properties. Diagenesis plays a decisive role in the reservoir development. Compaction and cementation destruct the capacity of the reservoir, while denudation and cataclasis improve the performance of the reservoir.