Microscopic Transport During Carbon Dioxide Injection in Crude Oil from Jimsar Oilfield Using Microfluidics

Huiying Guo (), Jianxiang Wang, Yuankai Zhang, Ning Xu, Zhaowen Jiang and Bo Bao ()
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Huiying Guo: Research Institute of Exploration and Development, Xinjiang Oilfield Company, Petrochina, Karamay 834000, China
Jianxiang Wang: School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
Yuankai Zhang: Research Institute of Exploration and Development, Xinjiang Oilfield Company, Petrochina, Karamay 834000, China
Ning Xu: Research Institute of Exploration and Development, Xinjiang Oilfield Company, Petrochina, Karamay 834000, China
Zhaowen Jiang: Research Institute of Exploration and Development, Xinjiang Oilfield Company, Petrochina, Karamay 834000, China
Bo Bao: School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China

Energies, 2025, vol. 18, issue 17, 1-19

Abstract: During the process of oil extraction, the urgent need for unconventional oil resources is driven by escalating global demand and the progressive depletion of conventional reserves. Shale oil represents a critical unconventional resource, with recovery efficiency being fundamentally constrained by the multiscale heterogeneity of shale reservoirs characterized by intricate networks of microscale fractures and nanoscale pores. To unravel pore structure impacts on microscopic transport phenomena, this study employed microfluidic chips replicating authentic shale pore architectures with pore depths as small as 200 nm to conduct immiscible flooding, constant volume depletion, and huff-n-puff experiments under representative reservoir conditions, with experiments reaching a maximum pressure of 40 MPa. The results show that large-pore and fine-throat structures create dual flow restrictions: the abrupt change in pore throat size amplifies the local flow resistance relative to the homogeneous structure, leading to a 78.09% decline in displacement velocity, while Jamin effect-induced capillary resistance reduces recovery efficiency, and even prevents some crude oil in the pore from being driven out. Slug flow occurred in the experiment, with calculated capillary numbers (Ca) of 0.0015 and 0.0026. This slug flow impedes microscopic transport efficiency, and lower Ca values yield more distinct liquid slugs. CO 2 exhibited effective extraction capabilities for light crude oil components, enriching residual heavy components that impeded subsequent extraction. When contact time was tripled under experimental conditions, this ultimately led to a 25.6% reduction in recovery rate. This investigation offers valuable insights into microscopic transport mechanisms within shale oil systems and provides practical guidance for optimizing shale reservoir development strategies.

Keywords: shale oil reservoir; CO 2 immiscible flooding; CO 2 huff-n-puff; microscopic transport; microfluidics (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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