Pore throat structure and classification of Paleogene tight reservoirs in Jiyang depression, Bohai Bay Basin, China

WANG Yongshi,GAO Yang,FANG Zhengwei

Fig. 2. Typical microscopic thin section photos of Paleogene tight sandstone and sandy conglomerate in the Jiyang depression. (a) Well Y935, upper Sha4 Member, 3885.39 m, pebbled heterogranular feldspar lithic sandstone, argillaceous matrix supported, particles of different sizes floating in argillaceous matrix (-); (b) Well F31-10, upper Sha 4 Member, 3254.67 m, calcareous heterogranular lithic arkose, primary pores with an infill of calcite cements (+); (c) Well S541-1, middle Sha3 Member, 3150.10 m, calcareous fine-grained lithic arkose, pores with an infill of carbonate cements (+); (d) Well L853-2, Sha4 Member, 2742.60 m, calcareous medium-grained feldspar lithic sandstone, calcite basal cementation, small porosity (-); (e) Well J503, lower Sha3 Member, 4048.30 m, fine-grained lithic arkose, rich in residual primary intergranular pores (-); (f) Well L853-2, upper Sha 4 Member, 2756.95 m, conglomerate with selective corrosion of gravels, rich in secondary dissolved pores (-); (g) Well Y34-100, Sha3 Member, 3555.61 m, heterogranular lithic arkose, rick in intragranular cracks, harbor-like corrosion along cracks (-); (h) Well Y935, upper Sha4 Member, 3915.22 m, pebbly heterogranular lithic arkose, rich in fractures at the fringe of gravels (-).