运用流体包裹体资料探讨鄂尔多斯盆地姬塬地区长9油藏史

Dating of hydrocarbon accumulation by fluid inclusion characteristics in the Chang9 of Yanchang Formation in Jiyuan area, the Ordos Basin

时保宏 张艳 张雷 黄静 唐朝

Shi Baohong Zhang Yan Zhang lei HuangJing Tang Chao

鄂尔多斯盆地姬塬地区三叠系延长组长9油层组是该区油藏发育的重点层位。在区域地质研究的基础上，通过流体包裹体偏光-荧光观察、均一温度测试、荧光光谱及红外光谱等分析方法，结合埋藏热演化史资料，确定了姬塬地区长9油藏的充注期次。分析表明，长9储层烃类包裹体物理相态主要为发绿色、黄绿色荧光的液态烃、含气烃的液态烃两类。与其共生的盐水包裹体均一温度分布连续，具有明显的单峰分布特征，对应温度为100～120 ℃，盐度分布也较集中，峰值区间NaCl浓度为3%~5%，表明发生过一期连续、流体性质和交换作用变化不大的烃类运移、充注过程。同样，石油包裹体荧光光谱及红外光谱特征及参数统计结果也佐证了姬塬地区长9储层经历了一期烃类充注，充注的有机质成熟度较高，烃类包裹体荧光光谱主峰波长、形态相似，波峰近似，为495 nm，对应绿色、黄绿色荧光区。结合研究区埋藏史、地热史综合分析得出，姬塬地区长9原油充注过程发生距今120～130 Ma，即早白垩世中、晚期为主要的油气成藏期。

Chang9 oil layer of the Triassic Yanchang Formation is a key horizon for reservoir development in Jiyuan area, Ordos Basin.The characteristics of fluid inclusions in Chang9 reservoir in Jiyuan area were analyzed systematically based on the measurements of Fourier transform infrared spectroscopy, fluorescence spectroscopy, and homogenization temperature to determine, in combination with the burial-thermal history, the phases and periods of hydrocarbon migration and accumulation.The results show that there are two types of hydrocarbon inclusions in the reservoir of Chang9, namely liquid hydrocarbon inclusions and gas liquid hydrocarbon inclusions with green or yellow-green fluorescence.The homogenization temperature of brine inclusions associated with the hydrocarbon inclusions has a continuous distribution with a 100-120 ℃ peak value.Salinity distribution is relatively concentrated with a peak value of 3-5 wt%NaCl.These cha-racteristics indicate that there is one major phase of oil migration and accumulation in the study area.Consistently, fluorescence spectroscopy and Fourier transform infrared spectroscopy data demonstrate that the Chang9 reservoir has undergone one phase of hydrocarbon charging with high organic matter maturity, with yellow-green and green fluorescence, corresponding to the fluorescence spectrum of 495nm.The analysis of burial and thermo-evolutionary history of Chang9 oil layer show that the hydrocarbon charging occurred mainly in mid-late stage of the Early Cretaceous.

10.11743/ogg20150103