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利用包裹体显微测温、显微荧光、显微红外光谱分析技术,结合埋藏史和热史模拟分析,探讨了鄂尔多斯盆地东南部X地区延长组长7油层组成藏期次.结果表明:研究区长7油层组主要发育两期油气包裹体,第1期油气包裹体沿石英颗粒次生加大内侧分布,或沿未切及石英颗粒次生加大边的成岩微裂缝,或成群、成带分布于长石颗粒内等,同期石油包裹体成分中长链烷烃质量分数相对较高,成熟度较低,同期盐水包裹体均一温度峰值为80~100℃;第2期油气包裹体沿切穿石英或长石颗粒的晚期微裂缝成线状或带状分布,同期石油包裹体成分中长链烷烃质量分数相对较低,成熟度较高,同期盐水包裹体均一温度峰值为85~100℃.综合分析认为研究区延长组长7油层组存在2期成藏,分别为早白垩世中晚期的大规模石油成藏和晚白垩世晚期到古近纪早期的晚期构造抬升调整成藏.
The compositional period of Chang 7 oil layer of Yanchang Formation in X area of southeast Ordos Basin was discussed by means of inclusions microscopic temperature measurement, micro-fluorescence and microscopic infrared spectroscopy analysis combined with burial history and thermal history simulation.The results show that: There are mainly two oil and gas inclusions in the Chang 7 oil layer. The first oil and gas inclusions are distributed along the secondary growth of quartz grains secondary to the inner distribution, along the diagenetic microfractures secondary to the uncut and quartz grains, In the same period, the content of mid-long-chain paraffin in petroleum inclusion is relatively high and the maturity is low. The homogenization temperature peak of the brine inclusions is 80 ~ 100 ℃ in the same period. The second phase of oil-gas inclusions The late microcracks cut through quartz or feldspar grains are linear or banded. In the same period, the content of medium-long paraffins in petroleum inclusion is relatively low and the maturity is relatively high. The homogenization temperature of the salt inclusions in the same period is 85-100 ℃ .A comprehensive analysis shows that there are two stages of hydrocarbon accumulation in Chang7 reservoir of Yanchang Formation in the study area, namely large-scale petroleum accumulation in the middle and late Early Cretaceous and late tectonic uplift and accumulation in the late Late Cretaceous to early Paleogene, respectively.