Open AccessMolecular and carbon isotopic characteristics of C6-14 hydrocarbons in the condensates from Kekeya oil field, Southwest Depression of the Tarim Basin, China
Author(s) -
Q. Wang,
Wanglu Jia,
Cong Yu,
Yan–Rong Zou,
Ping’an Peng
Publication year - 2020
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/600/1/012034
Subject(s) - isotopes of carbon , tarim basin , hydrocarbon , chemistry , alkane , analytical chemistry (journal) , crude oil , environmental chemistry , total organic carbon , organic chemistry , geology , paleontology , petroleum engineering
The condensates are important oil resources generally reserved in deep layers and mainly composed of light hydrocarbons. In this study, 10 condensates samples were collected from the Southwest Depression of the Tarim Basin, and treated with the purge-and-trap and headspace single-drop microextraction (HS-SDME) techniques to study the chemical and carbon isotope composition of the C6-14 hydrocarbons. The relative amount of C 6-14 hydrocarbons is significantly different between the samples. But there is still a good linear relationship between each two of the C 6-9 /C 10-14 , n C 6-9 / n C 10-14 and i C 6-9 / i C 10-14 ratios, indicating that the n -alkanes and isoalkanes (including aromatics) are approximately evaporated with the same ratio. And the relative amount of C 6-14 n -alkanes in the samples is deceased as the depth increasing. The δ 13 C values of the C 7-14 n-alkanes are in a range of -30.5‰∼-25‰, and consistent with the δ 13 C values of C 14+ n -alkanes that have been reported earlier. The depth might have an unpredicTable effect on the δ 13 C value when it is over 6000 m, because the samples with the highest and lowest δ 13 C values all come from the layers at similar depths. This work might suggest that the purge-and-trap and HS-SDME techniques were practicable and reliable methods to study the light hydrocarbons in condensates, and the results could improve the understanding of the condensates from the study area.