Characteristics of Fluid Inclusions and Their Constraints on Timing of Hydrocarbon Filling in the Yacheng Area of Qiongdongnan Basin, South China

Key words: 
• fluid inclusion /
• times of hydrocarbon charging and migration /
• reservoir /
• Qiongdongnan basin /

Abstract: The fluid inclusion of reservoir is one of important means to reveal the time of oil and natural gas charging. In present study the time of oil and natural gas charging in Yacheng and Lingshui Formation in Yacheng area of the Qiongdongnan Basin, southern China have been investigated by the analysis of type, distribution, fluorescence and homogenization temperature of fluid inclusions in samples of 5 Wells. The results indicated that the oil and natural gas bearing hydrothermal fluids have been charged twice into the sandstone reservoirs in the Paleogene reservoir. The first charge stage was characterized by condensategas with buffyellow fluorescent light, its hydrocarbon fluid inclusions are dominated by liquid hydrocarbon inclusions and gasliquid hydrocarbon inclusions, and the homogenization temperature (Th) of coeval aqueous inclusions ranges from 130℃ to 160℃. The time of first condensategas charging had been estimated at late Miocene to early Pliocene based on the regional burial thermal evolution history. The second charged stage was characterized by oil and natural gas with light blue fluorescence. Their hydrocarbon fluid inclusions were dominanted by gas hydrocarbon inclusions, gasliquid hydrocarbon inclusions and threephase hydrocarbon inclusions, the Th of coeval aqueous inclusions showed higher range from 160℃ to 190℃ than the 1st charged stage, and the charging time was estimated as Quaternary. 