Table 2 Reservoir characteristics and mineral composition in different regions.

Changqing¹⁸

The main minerals include quartz, potassium feldspar, plagioclase, calcite, and clay minerals.

Quartz and clay minerals are the main minerals. Plagioclase is much more than potassium feldspar.

The porosity is between 6% and 12%, and the permeability is less than 1 mD. It is greatly affected by cementation and compaction.

The common pore types are residual primary pores, a small amount of intergranular dissolved pores and micro-fractures. It is strong heterogeneity.

Daqing¹⁹

The content of quartz is high, while the content of clay minerals is relatively low. Some sections contain high carbonate minerals.

The porosity is between 8% ~ 15%. The permeability is between 0.1 ~ 1mD. The dissolution is obvious.

The common pore types are intergranular pores, intragranular dissolved pores and a small amount of micro-fractures.

Xinjiang²⁰

The proportion of clay minerals is relatively high, and the rock contains abundant carbonate minerals.

The porosity is between 10% ~ 15%. The permeability is between 0.01 ~ 1mD. Micro and nano pores are well-developed.

The common pore types are intergranular pores, micro-pores, dissolution pores, matrix fractures and structural fractures.

Jilin²¹

The mineral composition is primarily quartz. The content of feldspar is low.

The porosity is between 8% ~ 12%. The permeability is between 0.1 ~ 1mD. Volcanic debris or tuffaceous cementation makes the reservoir tighter.

The common pore types are intergranular pores, intragranular dissolved pores, micro-fractures. It is strong heterogeneity.