Genesis of calcite vein in basalt and its effect on reservoir quality: A case study of the Carboniferous in the east slope of Mahu sag, Junggar Basin, NW China

XIA Lu,CAO Yingchang,BIAN Baoli,LIU Hailei,WANG Xiaoxue,ZHAO Yiwei,YAN Miaomiao

Fig. 2. Characteristics of core fractures in Madong area (blue box: sample cutting position; yellow box: position of thin section; red circle: position of microzone test; green box: micro-drilling position at the thin-section scale). (a) At 3877.13 m in Well Ma 201, two low-angle fractures and one high-angle fracture, calcite filling; (b) cross-section photograph of the core sample in Fig. (a) after cutting; (c) at 4679.80 m in Well Madong 3, high-angle fracture and low-angle fractures, calcite filling; (d) at 5334.10 m in Well Xiayan 2, horizontal fractures and vertical fractures, calcite filling; (e) at 5374.50 m in Well Yan 001, vertical fractures terminating near horizontal or low-angle fractures, calcite filling.