Genesis and Geological Significance of the Black Oil Reservoir with a Condensate Gas Cap in the Baijiantan Formation of Hefeng 3 Block, Junggar Basin, NW China
- 1Chengdu University of Technology , , , ,
- 2PetroChina Xinjiang Oilfield Company , , , ,
- 3Yangtze University , , ,
Abstract
The Triassic Baijiantan Formation in the Hefeng 3 block, Junggar Basin, hosts an unusual hydrocarbon accumulation characterized by the coexistence of conventional black oil and a condensate gas cap within a single reservoir. This study integrates geochemical data, PVT simulations, and fluid inclusion analysis to unravel its genesis. Results show that the reservoir is a medium-porosity, ultralow-permeability system. The black oil originated from mature Fengcheng Formation source rocks, whereas the gas cap comprises mixed-source kerogen-cracking gases from both the Fengcheng Formation and Carboniferous sources. We propose a two-stage charging model: early accumulation of Fengcheng-derived black oil, followed by late injection of highly mature Carboniferous-derived dry gas. Evaporative fractionation induced by gas invasion transformed the original volatile oil into the present-day black oil–condensate gas cap configuration. This model challenges conventional single-source interpretations and provides a new genetic framework for complex fluid-phase reservoirs in the Junggar Basin. Our findings offer practical exploration guidance for similar composite reservoirs in superimposed basins worldwide.
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BibTeX
@article{chen2026genesis,
title = {{Genesis and Geological Significance of the Black Oil Reservoir with a Condensate Gas Cap in the Baijiantan Formation of Hefeng 3 Block, Junggar Basin, NW China}},
author = {Xinyu Chen and Akedan Sikandier and Zhongchen Ba and Meirui Hua and Zhaolin Pu and Shaoyang Geng},
journal = {ACS Omega},
year = {2026},
month = oct,
doi = {10.1021/acsomega.6c06198},
url = {https://pubs.acs.org/acsodf/article/doi/10.1021/acsomega.6c06198/5455822/Genesis-and-Geological-Significance-of-the-Black},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Genesis and Geological Significance of the Black Oil Reservoir with a Condensate Gas Cap in the Baijiantan Formation of Hefeng 3 Block, Junggar Basin, NW China
AU - Xinyu Chen
AU - Akedan Sikandier
AU - Zhongchen Ba
AU - Meirui Hua
AU - Zhaolin Pu
AU - Shaoyang Geng
PY - 2026
DA - 2026/10/22
JO - ACS Omega
DO - 10.1021/acsomega.6c06198
UR - https://pubs.acs.org/acsodf/article/doi/10.1021/acsomega.6c06198/5455822/Genesis-and-Geological-Significance-of-the-Black
AB - The Triassic Baijiantan Formation in the Hefeng 3 block, Junggar Basin, hosts an unusual hydrocarbon accumulation characterized by the coexistence of conventional black oil and a condensate gas cap within a single reservoir. This study integrates geochemical data, PVT simulations, and fluid inclusion analysis to unravel its genesis. Results show that the reservoir is a medium-porosity, ultralow-permeability system. The black oil originated from mature Fengcheng Formation source rocks, whereas the gas cap comprises mixed-source kerogen-cracking gases from both the Fengcheng Formation and Carboniferous sources. We propose a two-stage charging model: early accumulation of Fengcheng-derived black oil, followed by late injection of highly mature Carboniferous-derived dry gas. Evaporative fractionation induced by gas invasion transformed the original volatile oil into the present-day black oil–condensate gas cap configuration. This model challenges conventional single-source interpretations and provides a new genetic framework for complex fluid-phase reservoirs in the Junggar Basin. Our findings offer practical exploration guidance for similar composite reservoirs in superimposed basins worldwide.
SN - 2470-1343
ER -