Carbonate reservoirs of the Ordovician Lianglitage Formation in Tazhong26-24 wellblock are abundant in hydrocarbon inclusions.Three stages of hydrocarbon inclusions

including Ⅰ

Ⅱ and Ⅲ

are identified in the study area through analyses of occurrence

growth relationship and characteristics of the hydrocarbon inclusions

as well as microthermometric analysis of hydrocarbon inclusions and their coexisting aqueous inclusions.The stage Ⅰ inclusions(Ⅰ:OL+OLG) are dominated by light brown and colorless liquid hydrocarbon inclusions which exhibit moderate yellow to yellowish-white fluorescence under the UV-light.The stage Ⅱ inclusions(Ⅱ:OLG+OG) are mainly colorless and extremely light brown oil & gas inclusions with strong blue white to blue fluorescence under the UV-light.The stage Ⅲ inclusions(Ⅲ:OLG+OG+OA)are mainly light brown

brown and deep brown oil & gas hydrocarbon inclusions which are characterized by strong yellow to tan-colored fluorescence under the UV-light.Moreover

they were formed within temperature ranges of 80~90℃

90~100℃ and 97~110℃ respectively.Finally

in combination with the geological background of the study area

we believe that there are three accumulation periods in the Lianglitage Formation of Tazhong26-24 wellblock:intermedium hydrocarbon accumulation in the Late Hercynian period

light oil-condensates accumulation in the Early Himalayan period and highly mature hydrocarbon accumulation in the Late Himalayan period.