Orderly coexistence and accumulation models of conventional and unconventional hydrocarbons in Lower Permian Fengcheng Formation, Mahu sag, Junggar Basin

ZHI Dongming,TANG Yong,HE Wenjun,GUO Xuguang,ZHENG Menglin,HUANG Liliang

Fig. 5. Microsopic photos showing the lithologic characteristics of the reservoir rocks of the Fengcheng Formation, from well MY1, Mahu sag. (a) 4596.30 m, silicified lime-bearing dolomitic mudstone, thin section (-); (b) 4596.3m, silicified lime-bearing dolomitic mudstone, thin section (+); (c) 4632.20 m, silicified dolomitic siltstone, thin section (+); (d) 4664.80 m, mud-bearing fine-grained siltstone, thin section (+); (e) 4745.10 m, organic matter-bearing limy shale, thin section (+); (f) 4745.30 m, dolomite-bearing argillaceous siltstone, with fractures filled by silicon and calcite, thin section (+); (g) 4910.20 m, tuffaceous pebble-bearing sandstone, thin section (+); (h) 4911.80 m, tuffaceous lithic sandstone, thin section (+); (i) 4706.88 m, dolomitic mudstone, with micron pores, photo of scanning electron microscope, with a porosity of 4.9% and permeability of 0.031×10-3 μm2; (j) 4612.31 m, dolomitic siltstone, with intergranular dissolution pores, photo of scanning electron microscope, with a porosity of 8.2% and permeability of 0.012× 10-3 μm2; (k) 4612.31 m, dolomitic siltstone, with oil immersion in dissolution pores and intergranular pores, photo of scanning electron microscope; (l) 4612.31 m, dolomitic siltstone, with oil film in matrix pores, photo of scanning electron microscope.