Oil & Gas Geology ›› 2017, Vol. 38 ›› Issue (2): 209-218.doi: 10.11743/ogg20170201

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Fluid inclusion evidence for multi-period oil charge in Shahejie Member 4, Bonan Subsag,Bohai Bay Basin

Lin Hongmei1,2, Cheng Fuqi1, Wang Yongshi2, Song Guoqi3   

  1. 1. School of Geosciences, China University of Petroleum, Qingdao, Shandong 266580, China;
    2. Exploration and Development Research Institute, Shengli Qilfield Company, SINOPEC, Dongying, Shandong 257015, China;
    3. Shengli Oilfield Company, SINOPEC, Dongying, Shandong 257001, China
  • Received:2015-11-13 Revised:2016-08-09 Online:2017-04-28 Published:2017-05-04

Abstract: To confirm oil charge stages in the Bonan Subsag,Bohai Bay Basin,Twenty six samples collected from twenty four wells in Shahejie member 4(Es4) were used for fluid inclusion analysis.Based on microscopic identification,micro-beam fluorescence spectra and homogenization temperature testing in combination with sedimentary burial and thermal evolution histories,oil charge stages and their timings were obtained.There mainly developed three types of inclusions in the Es4 reservoirs including aqueous inclusions,oil inclusions and hydrocarbon brine inclusions.In addition,asphalt inclusion and filling asphalt in cracks and pores were also observed in some samples.Fluorescence colors of oil inclusions mainly are yellow-yellowgreen and blue-white,with a little of orange color.Main peak wavelength (λmax) distribution of orange,yellow-yellowgreen and blue-white oil inclusions are 555.76-576.88,513.25-555.76,and 491.13-497.93 nanometers respectively.Red-green entropy Q650/500 and Qt 535 of the three colors oil inclusions are 0.21-0.39 and 2.25-2.71,0.43-0.96 and 0.99-2.45,and 0.95-1.17 and 0.60-1.13 respectively.Homogenization temperatures of coeval aqueous inclusions of the three colors oil inclusion are 92.6-112.2,106.4-143.7(mainly 120-140) and 143.2-162.7 degree centigrade.Conclusion could be drawn that reservoirs in the Es4 had experienced at least three oil charging stages(early,middle and later stages)with different maturity of the oils.By positioning the aqueous inclusions homogenization temperature values on sedimentary burial and thermal evolution history chart,the geological times of the three oil charging stages are obtained which are 30.7-27.7,18-5 and 3.8-0 million years respectively.Current oil and gas found in the Es4 were mainly accumulated during the second and the third charging stages.

Key words: micro-beam fluorescence spectrum, homogenization temperature, fluid inclusion, multi-stage charging of oil and gas, Shahejie member 4, Bonan Subsag, Bohai Bay Basin

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