Oil & Gas Geology ›› 2015, Vol. 36 ›› Issue (1): 17-22.doi: 10.11743/ogg20150103

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

Shi Baohong1, Zhang Yan2, Zhang lei2, HuangJing2, Tang Chao2   

  1. 1. School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China;
    2. National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields, Changqing Oilfield Company, PetroChina, Xi'an, Shaanxi 710018, China;
    3. Research Institute of Exploration and Development, Changqing Oilfield Company, PetroChina, Xi'an, Shaanxi 710018, China
  • Received:2014-01-15 Revised:2014-10-20 Online:2015-02-08 Published:2015-02-11

Abstract:

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.

Key words: homogenization temperature, FTIR, fluorescence spectrum, hydrocarbon accumulation timing, fluid inclusion, Jiyuan area, Ordos Basin

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