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In order to assess the feasibility of energy supplement and EOR of lacustrine shale-type shale oil by integration of imbibition and CO2 huff-n-puff, taking shale cores with three lithologic types of Qingshankou Formation in Songliao Basin as the study object, namely felsic shale (SLS), organic-rich lamellar clayey shale (HLS) and lamellar clayey shale (MLS). The natural depletion characteristics of pressure maintaining cores were investigated by imbibition and accompanying gas production experiments, and the microscopic production characteristics of shale oil during multiple rounds of huff-n-puff of imbibition surfactant and CO2 were quantitatively analyzed by joint experiments, including high pressure mercury intrusion, nitrogen adsorption, NMR measurement and huff-n-puff tests. The results showed that the produced gas during natural depletion process was mainly composed of methane. With the extension of gas production time, the percentage composition of C2–C4 components increased, and the percentage composition of C6–C20 components increased. The oil components can be effectively extracted by gas production. The major contribution of nano-scale pore to the total recovery for the shale cores with three lithologic types was gradually increased with one round of imbibition huff-n-puff and subsequent two rounds of CO2 huff-n-puff. The oil recovery in micron-scale pores of the shale cores was the highest, reached over 83%. The SLS core had the highest percentage of pore volume above sub-micron scale and felsic mineral components, and its oil recovery in sub-micron scale pores and the contribution of micron-scale pores to recovery were both the highest, which were 71.66% and 14.54%, respectively. Through the synergistic effect of energy supplement by CO2 huff-n-puff after imbibition huff-n-puff, the SLS core had the highest recovery rate as 48.75%, and that of the HLS core and the MLS core were 48.75 and 34.70% respectively. The research results can provide method reference and data support for shale oil development.

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Microscopic Production Characteristics of Imbibition Huff-n-Puff and Accompanying Gas of Laminated Shale Based on NMR

  • 会议论文

  • 发表日期：

    2025年

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  • Lan-qing Fu,
  • Hong-an Chen,
  • Bin-hui Li,
  • Yong Liu,
  • Da-peng Dong,
  • Sen Deng

摘要

In order to assess the feasibility of energy supplement and EOR of lacustrine shale-type shale oil by integration of imbibition and CO2 huff-n-puff, taking shale cores with three lithologic types of Qingshankou Formation in Songliao Basin as the study object, namely felsic shale (SLS), organic-rich lamellar clayey shale (HLS) and lamellar clayey shale (MLS). The natural depletion characteristics of pressure maintaining cores were investigated by imbibition and accompanying gas production experiments, and the microscopic production characteristics of shale oil during multiple rounds of huff-n-puff of imbibition surfactant and CO2 were quantitatively analyzed by joint experiments, including high pressure mercury intrusion, nitrogen adsorption, NMR measurement and huff-n-puff tests. The results showed that the produced gas during natural depletion process was mainly composed of methane. With the extension of gas production time, the percentage composition of C2–C4 components increased, and the percentage composition of C6–C20 components increased. The oil components can be effectively extracted by gas production. The major contribution of nano-scale pore to the total recovery for the shale cores with three lithologic types was gradually increased with one round of imbibition huff-n-puff and subsequent two rounds of CO2 huff-n-puff. The oil recovery in micron-scale pores of the shale cores was the highest, reached over 83%. The SLS core had the highest percentage of pore volume above sub-micron scale and felsic mineral components, and its oil recovery in sub-micron scale pores and the contribution of micron-scale pores to recovery were both the highest, which were 71.66% and 14.54%, respectively. Through the synergistic effect of energy supplement by CO2 huff-n-puff after imbibition huff-n-puff, the SLS core had the highest recovery rate as 48.75%, and that of the HLS core and the MLS core were 48.75 and 34.70% respectively. The research results can provide method reference and data support for shale oil development.