Abstract: The fractural types in Hongshanzui-Chepaizi (HongChe) fault belt in Junggar basin mainly include 4 non-structural fractures (interlayer fracture, stylolite, dissolution fissure and diagenetic fissure) and 4 structural fractures (horizontal fracture, low-angle fracture, diagonal seam and high-angle fracture), according to the study of core fracture and well logging data. The statistics show that about 50% of HongChe fault fractures are totally filled, 37% semi-filled, 13% unfilled. The types of filled minerals are calcite, anhydrite, zeolite, silica, chlorite, and other authigenic ones. The fissure width ranges from 0.1 mm to 20 mm, dominated by 1~4 mm; the fractural dip ranges from 10° to 50°, which account for more than 90% of statistical fractures. The trend of the fractures is dominated by NE , the secondary is near SN and NW. Favorable structural positions where fractures developed are mainly on structural highs, structural intersection and fault-developed area. The fracture developing extent is increasing with the increase of fragility of reservoir rocks. The fracture development and opening are all decreasing with the increase of reservoir burial depth.

Key words: Junggar basin, fractural characteristic, Carboniferous, volcanic rock, HongChe fault belt