Petroleum geological conditions and exploration potential of Lower Paleozoic carbonate rocks in Gucheng Area, Tarim Basin, China

CAO Yinghui,WANG Shan,ZHANG Yajin,YANG Min,YAN Lei,ZHAO Yimin,ZHANG Junlong,WANG Xiandong,ZHOU Xiaoxiao,WANG Hongjiang

Fig. 7. Slice characteristics of Lower Paleozoic carbonate reservoirs in the Gucheng area. (a) Well GC601, 6076.37 m, the third member of Yingshan Formation, fine- to medium-grained dolomite with residual grain structure, cast thin section, plane polarized light. (b) Well GC601, 6049.52 m, the third member of Yingshan Formation, medium-grained dolomite with phantom grain structure and intercrystalline (dissolution) pores, cast thin section, plane polarized light. (c) Well GC12, 6190.00 m, the third member of Yingshan Formation, medium-grained dolomite, with vugs and fractures partially filled by quartz, cast thin section, plane polarized light. (d) Well GC601, 6123.38 m, the third member of Yingshan Formation, medium- to coarse-grained dolomite, with vugs filled with seepage silt, ordinary slice, plane polarized light. (e) Well GC8, 6733.51 m, Upper Cambrian, micrite dolomite with residual grain structure, with calcite-filled vugs, ordinary slice, plane polarized light. (f) Well CT1, 6888.28 m, Upper Cambrian, epiphytic silicified rock, ordinary slice, plane polarized light. (g) Well CT1, 6888.28 m, Upper Cambrian, breccia dolomite, with vugs, coarse-grained saddle-like dolomite cemented between breccia, core. (h) Well CT2, 6729.50 m, Upper Cambrian, intragranular solution pores, cast thin section, plane polarized light. (i) Well GC8, 6734.50 m, Upper Cambrian, medium- to coarse-grained dolomite, with intercrystalline solution pores and vugs, cast thin section, plane polarized light. (j) Well SN4, 6669.49 m, Yingshan Formation, calcareous tight siliceous rock, with vugs partially filled with columnar quartz and fluorite, core. (k) Well SN4, 6670.48 m, Yingshan Formation, granular siliceous rock, with dissolution pores, cast thin section, plane polarized light. (l) Well GC11, 5702.18 m, Yijianfang Formation, sparite calcarenite and bioclastic limestone, ordinary slice, plane polarized light. (m) Well GC17, 5866.54 m, Yijianfang Formation, sparite oolitic limestone, ordinary slice, plane polarized light. (n) Well GC11, 5690.60 m, Yijianfang Formation, sparite calcarenite, with dissolution fractures, cast thin section, plane polarized light. (o) Well GC11, 5707.50 m, Yijianfang Formation, algae-bound limestone, with moldic pores, intragranular dissolution micro-pores, and micro-fractures, cast thin section, plane polarized light. (p) Well GC11, 5692.80 m, sparite calcarenite, with intragranular dissolution micro-pores, cast thin section, plane polarized light.