Effects of oil cracking on fluorescence color, homogenization temperature and trapping pressure reconstruction of oil inclusions from deeply buried reservoirs in the northern Dongying Depression, Bohai Bay Basin, China

Hongwei Ping, Honghan Chen, Régis Thiéry, Simon C. George

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The effects of oil cracking on fluorescence color, homogenization temperature (Tho) and trapping pressure (Pt) of oil inclusions from deeply buried reservoirs (DBRs) (3672–4359 m) in the northern Dongying Depression were determined based on fluorescence spectroscopy and homogenization temperatures of oil inclusions, kinetic modeling of crude oil cracking, and petroleum inclusion thermodynamics modeling.

The modeling results demonstrate that fluorescence color, Tho and predicted Pt have strong relationships with the transformation rate via cracking of oil to gas (Tr), and the formation temperature (Tf) that the inclusions experienced. The fluorescence color is hardly influenced at all during the initial stages of oil cracking (Tr < 13%, Tf < 160 °C), but fluorescence color begins to shift toward shorter wavelengths (blue shift) during progressive oil cracking (Tr < 24%, Tf < 190 °C). With further oil cracking, the fluorescence color may either experience no change or continue its blue shift. Eventually the fluorescence color will disappear as the aromatic compounds are completely cracked. The Tho increases at first (Tr < 24%, Tf < 190 °C), but then decreases or even becomes negative during major oil cracking. The reconstructed Pt values show a corresponding reverse trend.

Oil inclusions from DBRs and other shallow reservoirs in the Dongying Depression show an obvious blue shift in fluorescence color at a depth of approximate 4000 m (Tf = 160 °C) and generally contain solid bitumen below 4000 m, supporting the effect of oil cracking on fluorescence variation, consistent with the modeling result. The Tho from DBRs in the Minfeng area increases with increasing burial depth (Tf < 190 °C), which is also consistent with the modeling results. However, the Tho of oil inclusions with blue-white fluorescence from DBRs in the Shengtuo area did not show such a trend. Recent trapping, high trapping pressure and higher-maturity oil may have led to a low-degree of oil cracking, and thus less modification of Tho in the Shengtuo area.

Oil cracking results in consistent volume ratios of pyrobitumen to oil inclusions (Fvpy) in the same fluid inclusion assemblage, and the Fvpy value increases with oil cracking level, which can be used to recognize if oil cracking has occurred in oil inclusions and what level of oil cracking they have experienced.

As the oil cracking model used in this study did not account for the role of pressure, it is more applicable for oil inclusions that were trapped under normally pressured conditions. Oil inclusions trapped under overpressured conditions will be less influenced by oil cracking.

LanguageEnglish
Pages538-562
Number of pages25
JournalMarine and Petroleum Geology
Volume80
DOIs
Publication statusPublished - Feb 2017

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homogenizing
trapping
China
fluorescence
oils
inclusions
color
oil
basin
temperature
effect
blue shift
modeling
crude oil
trends

Keywords

  • Petroleum inclusion
  • Fluorescence spectroscopy
  • Homogenization temperature
  • Trapping pressure
  • Overpressure
  • Pyrobitumen
  • Oil cracking kinetics
  • Petroleum inclusion thermodynamics
  • modeling

Cite this

@article{fe22fa34fed34383bb944ad25c9a4151,
title = "Effects of oil cracking on fluorescence color, homogenization temperature and trapping pressure reconstruction of oil inclusions from deeply buried reservoirs in the northern Dongying Depression, Bohai Bay Basin, China",
abstract = "The effects of oil cracking on fluorescence color, homogenization temperature (Tho) and trapping pressure (Pt) of oil inclusions from deeply buried reservoirs (DBRs) (3672–4359 m) in the northern Dongying Depression were determined based on fluorescence spectroscopy and homogenization temperatures of oil inclusions, kinetic modeling of crude oil cracking, and petroleum inclusion thermodynamics modeling. The modeling results demonstrate that fluorescence color, Tho and predicted Pt have strong relationships with the transformation rate via cracking of oil to gas (Tr), and the formation temperature (Tf) that the inclusions experienced. The fluorescence color is hardly influenced at all during the initial stages of oil cracking (Tr < 13{\%}, Tf < 160 °C), but fluorescence color begins to shift toward shorter wavelengths (blue shift) during progressive oil cracking (Tr < 24{\%}, Tf < 190 °C). With further oil cracking, the fluorescence color may either experience no change or continue its blue shift. Eventually the fluorescence color will disappear as the aromatic compounds are completely cracked. The Tho increases at first (Tr < 24{\%}, Tf < 190 °C), but then decreases or even becomes negative during major oil cracking. The reconstructed Pt values show a corresponding reverse trend. Oil inclusions from DBRs and other shallow reservoirs in the Dongying Depression show an obvious blue shift in fluorescence color at a depth of approximate 4000 m (Tf = 160 °C) and generally contain solid bitumen below 4000 m, supporting the effect of oil cracking on fluorescence variation, consistent with the modeling result. The Tho from DBRs in the Minfeng area increases with increasing burial depth (Tf < 190 °C), which is also consistent with the modeling results. However, the Tho of oil inclusions with blue-white fluorescence from DBRs in the Shengtuo area did not show such a trend. Recent trapping, high trapping pressure and higher-maturity oil may have led to a low-degree of oil cracking, and thus less modification of Tho in the Shengtuo area. Oil cracking results in consistent volume ratios of pyrobitumen to oil inclusions (Fvpy) in the same fluid inclusion assemblage, and the Fvpy value increases with oil cracking level, which can be used to recognize if oil cracking has occurred in oil inclusions and what level of oil cracking they have experienced. As the oil cracking model used in this study did not account for the role of pressure, it is more applicable for oil inclusions that were trapped under normally pressured conditions. Oil inclusions trapped under overpressured conditions will be less influenced by oil cracking.",
keywords = "Petroleum inclusion, Fluorescence spectroscopy, Homogenization temperature, Trapping pressure, Overpressure, Pyrobitumen, Oil cracking kinetics, Petroleum inclusion thermodynamics, modeling",
author = "Hongwei Ping and Honghan Chen and R{\'e}gis Thi{\'e}ry and George, {Simon C.}",
year = "2017",
month = "2",
doi = "10.1016/j.marpetgeo.2016.12.024",
language = "English",
volume = "80",
pages = "538--562",
journal = "Marine and Petroleum Geology",
issn = "0264-8172",
publisher = "Elsevier",

}

TY - JOUR

T1 - Effects of oil cracking on fluorescence color, homogenization temperature and trapping pressure reconstruction of oil inclusions from deeply buried reservoirs in the northern Dongying Depression, Bohai Bay Basin, China

AU - Ping, Hongwei

AU - Chen, Honghan

AU - Thiéry, Régis

AU - George, Simon C.

PY - 2017/2

Y1 - 2017/2

N2 - The effects of oil cracking on fluorescence color, homogenization temperature (Tho) and trapping pressure (Pt) of oil inclusions from deeply buried reservoirs (DBRs) (3672–4359 m) in the northern Dongying Depression were determined based on fluorescence spectroscopy and homogenization temperatures of oil inclusions, kinetic modeling of crude oil cracking, and petroleum inclusion thermodynamics modeling. The modeling results demonstrate that fluorescence color, Tho and predicted Pt have strong relationships with the transformation rate via cracking of oil to gas (Tr), and the formation temperature (Tf) that the inclusions experienced. The fluorescence color is hardly influenced at all during the initial stages of oil cracking (Tr < 13%, Tf < 160 °C), but fluorescence color begins to shift toward shorter wavelengths (blue shift) during progressive oil cracking (Tr < 24%, Tf < 190 °C). With further oil cracking, the fluorescence color may either experience no change or continue its blue shift. Eventually the fluorescence color will disappear as the aromatic compounds are completely cracked. The Tho increases at first (Tr < 24%, Tf < 190 °C), but then decreases or even becomes negative during major oil cracking. The reconstructed Pt values show a corresponding reverse trend. Oil inclusions from DBRs and other shallow reservoirs in the Dongying Depression show an obvious blue shift in fluorescence color at a depth of approximate 4000 m (Tf = 160 °C) and generally contain solid bitumen below 4000 m, supporting the effect of oil cracking on fluorescence variation, consistent with the modeling result. The Tho from DBRs in the Minfeng area increases with increasing burial depth (Tf < 190 °C), which is also consistent with the modeling results. However, the Tho of oil inclusions with blue-white fluorescence from DBRs in the Shengtuo area did not show such a trend. Recent trapping, high trapping pressure and higher-maturity oil may have led to a low-degree of oil cracking, and thus less modification of Tho in the Shengtuo area. Oil cracking results in consistent volume ratios of pyrobitumen to oil inclusions (Fvpy) in the same fluid inclusion assemblage, and the Fvpy value increases with oil cracking level, which can be used to recognize if oil cracking has occurred in oil inclusions and what level of oil cracking they have experienced. As the oil cracking model used in this study did not account for the role of pressure, it is more applicable for oil inclusions that were trapped under normally pressured conditions. Oil inclusions trapped under overpressured conditions will be less influenced by oil cracking.

AB - The effects of oil cracking on fluorescence color, homogenization temperature (Tho) and trapping pressure (Pt) of oil inclusions from deeply buried reservoirs (DBRs) (3672–4359 m) in the northern Dongying Depression were determined based on fluorescence spectroscopy and homogenization temperatures of oil inclusions, kinetic modeling of crude oil cracking, and petroleum inclusion thermodynamics modeling. The modeling results demonstrate that fluorescence color, Tho and predicted Pt have strong relationships with the transformation rate via cracking of oil to gas (Tr), and the formation temperature (Tf) that the inclusions experienced. The fluorescence color is hardly influenced at all during the initial stages of oil cracking (Tr < 13%, Tf < 160 °C), but fluorescence color begins to shift toward shorter wavelengths (blue shift) during progressive oil cracking (Tr < 24%, Tf < 190 °C). With further oil cracking, the fluorescence color may either experience no change or continue its blue shift. Eventually the fluorescence color will disappear as the aromatic compounds are completely cracked. The Tho increases at first (Tr < 24%, Tf < 190 °C), but then decreases or even becomes negative during major oil cracking. The reconstructed Pt values show a corresponding reverse trend. Oil inclusions from DBRs and other shallow reservoirs in the Dongying Depression show an obvious blue shift in fluorescence color at a depth of approximate 4000 m (Tf = 160 °C) and generally contain solid bitumen below 4000 m, supporting the effect of oil cracking on fluorescence variation, consistent with the modeling result. The Tho from DBRs in the Minfeng area increases with increasing burial depth (Tf < 190 °C), which is also consistent with the modeling results. However, the Tho of oil inclusions with blue-white fluorescence from DBRs in the Shengtuo area did not show such a trend. Recent trapping, high trapping pressure and higher-maturity oil may have led to a low-degree of oil cracking, and thus less modification of Tho in the Shengtuo area. Oil cracking results in consistent volume ratios of pyrobitumen to oil inclusions (Fvpy) in the same fluid inclusion assemblage, and the Fvpy value increases with oil cracking level, which can be used to recognize if oil cracking has occurred in oil inclusions and what level of oil cracking they have experienced. As the oil cracking model used in this study did not account for the role of pressure, it is more applicable for oil inclusions that were trapped under normally pressured conditions. Oil inclusions trapped under overpressured conditions will be less influenced by oil cracking.

KW - Petroleum inclusion

KW - Fluorescence spectroscopy

KW - Homogenization temperature

KW - Trapping pressure

KW - Overpressure

KW - Pyrobitumen

KW - Oil cracking kinetics

KW - Petroleum inclusion thermodynamics

KW - modeling

UR - http://www.scopus.com/inward/record.url?scp=85007583919&partnerID=8YFLogxK

U2 - 10.1016/j.marpetgeo.2016.12.024

DO - 10.1016/j.marpetgeo.2016.12.024

M3 - Article

VL - 80

SP - 538

EP - 562

JO - Marine and Petroleum Geology

T2 - Marine and Petroleum Geology

JF - Marine and Petroleum Geology

SN - 0264-8172

ER -