| The hydrocarbon accumulation stages of the Buqu carbonate reservoirs (J2b) in different tectonic units at Qiangtang Basin were still not clear. In this study, the carbonate reservoirs of the Buqu Formation in the Biluo Co area at Southern Qiangtang and in the Shengli River area at Northern Qiangtang were taken as research objects, and the petrography, microthermometry and salt measurement of fluid inclusions were carried out. The results showed that the Biluo Co area experienced three stages of hydrocarbon charging during the burial period. The first stage was in the Late Jurassic-Early Cretaceous, which was a large amount of oil charging period. The second stage was in the Late Cretaceous, which was oil and gas charging period. The third stage occurred in the early Paleogene, which was a large amount of natural gas charging. The Shengli River area also experienced three stages of hydrocarbon charging during the burial period. The first stage occurred in the Early Cretaceous, which was filled with a large amount of oil with minor natural gas. The second stage occurred in the Late Paleocene- Early Eocene, dominated by oil and gas filling. And the third stage of accumulation was in the late Eocene, filling a large amount of natural gas. The Buqu Formation in the both southern and northern Qiangtang developed fluid inclusions with relatively high homogenization temperature in the late stage, which is possibly related to the thrust faults or magmatic hydrothermal activities. The second accumulation was developed in the Cenozoic. In general, the hydrocarbon accumulation period of Southern Qiangtang was earlier than that of Northern Qiangtang. |