Preprints
https://doi.org/10.5194/egusphere-2023-272
https://doi.org/10.5194/egusphere-2023-272
30 Mar 2023
 | 30 Mar 2023
Status: this preprint is open for discussion.

The influence of various solvents extraction on chemical properties on Chang 7 shale, Ordos Basin, China

Yan Cao, Zhijun Jin, Rukai Zhu, and Kouqi Liu

Abstract. To explore the effect of various solvents extraction on the chemical property of shales, several lacustrine shales from Chang 7 member of the Upper Triassic Yanchang Formation, Ordos Basin with maturities from marginally mature (Tmax = 439 ℃) to late mature (Tmax = 456 ℃) were extracted by using acetone, tetrahydrofuran (THF), carbon disulfide (CS2), and benzene, respectively. Fourier transform infrared spectroscopy (FTIR) was employed to examine the functional groups of the samples before and after extraction with different solvents. The results showed that the extraction yield from shale with THF is significantly higher than that of other solvents, which may be related to the properties of the THF, including the aromatic structure, high boiling point, excellent Hansen solubility parameters, and strong polarity. The TOC-normalized yield of the mature sample J1 is significantly higher than that of other samples, which may be related to that the J1 sample is at the peak of hydrocarbon generation, thus a large number of kerogens were cracked into oil and bitumen. The aromaticity of organic matter (OM) increases with the increase of maturity. The length of the aliphatic chains of the organic matter first increased with the increase of maturity before late maturity stage, and then decreased in late maturity stage. The extraction of shales with solvents hardly changes the length of aliphatic chains. Higher aromaticity is observed in shale residues after THF extractions than other solvents (i.e., acetone, CS2, benzene).

Yan Cao et al.

Status: open (until 14 Jun 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2023-272', jiangming tian, 06 May 2023 reply
    • AC1: 'Reply on CC1', Yan Cao, 06 May 2023 reply
      • CC6: 'Reply on AC1', san zhang, 07 May 2023 reply
  • CC2: 'Comment on egusphere-2023-272', san zhang, 06 May 2023 reply
    • AC2: 'Reply on CC2', Yan Cao, 06 May 2023 reply
      • CC7: 'Reply on AC2', san zhang, 07 May 2023 reply
  • CC3: 'Comment on egusphere-2023-272', san zhang, 06 May 2023 reply
    • AC3: 'Reply on CC3', Yan Cao, 06 May 2023 reply
      • CC8: 'Reply on AC3', san zhang, 07 May 2023 reply
  • CC4: 'Comment on egusphere-2023-272', Peng Pang, 06 May 2023 reply
    • AC4: 'Reply on CC4', Yan Cao, 06 May 2023 reply
      • CC5: 'Reply on AC4', Peng Pang, 06 May 2023 reply

Yan Cao et al.

Yan Cao et al.

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Short summary
FTIR was performed on shales before and after extraction with four solvents. The extraction yield from shale with THF is significantly higher than other solvents. The TOC-normalized yield of mature sample is significantly higher than other samples. The aromaticity of organic matter increases and the length of aliphatic chains of organic matter doesn’t vary monotonically with increasing maturity. The results will help in the selection of organic solvents for oil-washing experiments of shales.