Hydrothermal dissolution of deep-buried carbonate rocks and its significance for hydrocarbon exploration in Shunnan area, the Tarim Basin: taking well Peng-1 in Shunnan area as a case

In order to reveal the genetic mechanism of deep-buried carbonate reservoirs, a study was made based on well Peng-1 in Shunnan area of the Tarim Basin. The core section of well Peng-1 revealed that a large number of fractures and dissolution pores were developed in the carbonate rocks with buried depth of over 7 500 m. Based on detailed core observation and description, it was found that the dissolution pores were mainly distributed in the Upper Cambrian dolomites in the lower part of the core section and few in the Lower Ordovician carbonates in the upper part of the core section. The diameter of pores increases gradually with the increase of burial depth, which indicated that the pores were formed by infiltration of deep-seated hydrothermal fluids rather than meteoric water. The similar δ13C values and 87Sr/86Sr ratios of different types of minerals (including dolomite and calcite) with host rocks indicated that the diagenetic fluids inherited the geochemical characteristics of original sequestered pore wat