Diagenetic Facies and Their Controls on the Quality of Tight Sandstone Reservoirs: A Case Study from the Upper Paleozoic Gas Reservoir in the Eastern Ordos Basin, North China

Table 1

Diagenetic facies of sandstone of research area.

Facies	Diagenetic facies	Diagenetic features	Pores	Rock types
A	Siliceous cementation intergranular pore facies	Quartz enlargement, siliceous cement filling pores, kaolinite, pressure dissolution	Residual primary intergranular pores, intergranular pores of kaolinite	Quartz sandstone	Constructive diagenesis
B	Carbonate dissolution pore facies	Strong dissolution of calcareous cement	Intergranular solution pores, mold pores	Lithic quartz sandstone, quartz sandstone
C	Matrix dissolution pore facies	Kaolinite, volcanic materials, and other matrix dissolved	Intergranular dissolved pores, intercrystalline dissolved pores, casting pores	Lithic sandstone, lithic quartz sandstone
D	Clastic dissolution pore facies	Dissolution of clastics and feldspar	Intergranular solution pores, mold pores
E	Matrix filling and strong compaction tight facies	High content of matrix, strong erosion and deformation of soft clastics	Pores not well developed	Lithic sandstone, lithic quartz sandstone	Destructive diagenesis
F	Carbonate cementation and metasomatism tight facies	High content of matrix and calcareous cement	Pores not well developed	Lithic sandstone