利用油包裹体荧光光谱确定齐家地区高台子油层致密油气成藏期次及其相对成熟度

Determination of accumulation periods and relative maturity of tight oil and gas in Gaotaizi oil reservoir of Qijia area by using fluorescence spectrum of oil inclusions

基于石油的荧光性,通过常规荧光光谱方法,对油包裹体的荧光光谱进行定量化描述,利用其主峰波长(λ_(max))、红绿熵(Q)及QF_(535)等属性参数,并根据λ_(max)与QF_(535)的相关关系特征,可以便捷而有效地开展油气充注期次的判识。齐家地区上白垩统青山口组高台子致密油储层中9块流体包裹体样品检测结果表明,高台子油层中发育发黄色、黄绿色、蓝绿色3种荧光颜色的油包裹体;高台子油层油包裹体λ_(max)与QF_(535)分布在3个区域,从黄色荧光区域→黄绿色荧光区域→蓝绿色荧光区域,QF_(535)值逐渐减小,反映了油包裹体中捕获原油的成熟度逐渐增高;并结合埋藏史、生烃史和包裹体均一温度研究,认为齐家地区高台子油层在地质历史时期共经历了3幕油气充注,早期原油充注发生在白垩纪嫩江晚期79—77Ma期间,对应于第1幕充注;晚期原油充注发生在晚白垩世明水期69—65Ma期间,对应于第2幕和第3幕充注。

Based on the fluorescence property of petroleum, the conventional fluorescence spectroscopy was adopted to quantitatively describe the fluorescence spectrum of-oil inclusions. The hydrocarbon charging events can be identified conveniently and effectively based on its attribute parameters （e.g. main peak wave length （λmax）, red-green entropy （Q） and QF535） and the relationship between ＂~m~ and QFs35. 9 samples of fluid inclusions taken from Gaotaizi tight oil reservoir of Qingshankou Formation, Upper Cretaceous in Qijia area were tested. It is indicated that the oil inclusions of three fluorescent colors （i.e., yellow, yellow-green and blue-green） are developed in Gaotaizi oil reservoir. λmax and QF535 of oil inclusions in Gaotaizi oil reservoir are distributed in three regions. The QF535 decreases gradually from yellow fluorescence region to yellow-green fluorescence region and to blue-green fluorescence region, reflecting the gradual increase of the maturity of crude oil entrapped in oil inclusions. Then, combined with the studies on burial history, hydrocarbon generation history and homogeneous temperature of inclusions, it is concluded that Gaotaizi oil reservoir in Qijia area has experienced 3 hydrocarbon charging events in the period of geological history. The early charging of crude oil occurred in the late stage of Cretaceous Nenjiang （79-77 Ma）, corresponding to the first event of charging, and the late charging occurred in the Mingshui period of Late Cretaceous （69-65 Ma）, corresponding to the second and third events of charging.