Fluid Flow Behavior in Nanometer-Scale Pores and Its Impact on Shale Oil Recovery Efficiency

Xiangji Dou, Menxing Qian, Xinli Zhao (), An Wang, Zhengdong Lei, Erpeng Guo and Yufei Chen
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Xiangji Dou: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China
Menxing Qian: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China
Xinli Zhao: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China
An Wang: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China
Zhengdong Lei: Research Institute of Petroleum Exploration & Development, PetroChina Company Limited, Beijing 100083, China
Erpeng Guo: Research Institute of Petroleum Exploration & Development, PetroChina Company Limited, Beijing 100083, China
Yufei Chen: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China

Energies, 2024, vol. 17, issue 18, 1-22

Abstract: Shale oil reservoirs, as an unconventional hydrocarbon resource, have the potential to substitute conventional hydrocarbon resources and alleviate energy shortages, making their exploration and development critically significant. However, due to the low permeability and the development of nanopores in shale reservoirs, shale oil production is challenging and recovery efficiency is low. During the imbibition stage, fracturing fluid displaces the oil in the pores primarily under capillary forces, but the complex pore structure of shale reservoirs makes the imbibition mechanism unclear. This research studies the imbibition flow mechanism in nanopores based on the capillary force model and two-phase flow theory, coupled with numerical simulation methods. The results indicated that within a nanopore diameter range of 10–20 nm, increasing the pore diameter leads to a higher imbibition displacement volume. Increased pressure can enhance the imbibition displacement, but the effect diminishes gradually. Under the water-wet conditions, the imbibition displacement volume increases as the contact angle decreases. When the oil phase viscosity decreases from 10 mPa·s to 1 mPa·s, the imbibition displacement rate can increase by 72%. Moreover, merely increasing the water phase viscosity results in only a 5% increase in the imbibition displacement rate. The results provide new insights into the imbibition flow mechanism in nanopores within shale oil reservoirs and offer a theoretical foundation and technical support for efficient shale oil development.

Keywords: shale oil; single nanopore; capillary force; imbibition displacement; multifactor analysis (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: 2024
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