新疆石油地质

新疆石油地质 ›› 2022, Vol. 43 ›› Issue (zk(English)): 136-142.

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EOR of CO2 Flooding in Low-Permeability Sandy Conglomerate Reservoirs

LI Yan1,2, ZHANG Di3, FAN Xiaoyi1,2, ZHANG Jintong1,2, YANGRuisha1,2, YE Huan1,2   

  1. 1. Research Institute of Exploration and Development, Henan Oilfield Company, Sinopec, Zhengzhou, Henan 450000, China;
    2. Henan Provincial Key Laboratory of Enhanced Oil Recovery, Nanyang, Henan 473132, China;
    3. Seismological Bureau of Henan Province, Zhengzhou, Henan 450000, China
  • 收稿日期:2021-11-02 修回日期:2021-11-18 出版日期:2023-01-01 发布日期:2023-07-28

EOR of CO2 Flooding in Low-Permeability Sandy Conglomerate Reservoirs

LI Yan1,2, ZHANG Di3, FAN Xiaoyi1,2, ZHANG Jintong1,2, YANGRuisha1,2, YE Huan1,2   

  1. 1. Research Institute of Exploration and Development, Henan Oilfield Company, Sinopec, Zhengzhou, Henan 450000, China;
    2. Henan Provincial Key Laboratory of Enhanced Oil Recovery, Nanyang, Henan 473132, China;
    3. Seismological Bureau of Henan Province, Zhengzhou, Henan 450000, China
  • Received:2021-11-02 Revised:2021-11-18 Online:2023-01-01 Published:2023-07-28
  • About author:LI Yan, E-mail: liyan_2021@yeah.net

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摘要： The low-permeability sandy conglomerate reservoirs of Benbutu oilfield in Yanqi basin was developed by water flooding in the early stage. While along with water flooding, the reservoirs were seriously damaged, it was even harder to inject water into the reservoirs and the recovery rate stayed in a low level, therefore, it is urgent to switch flooding agent to further improve the recovery rate. In order to determine the feasibility of CO2 injection in the low-permeability sandy conglomerate reservoirs in Benbutu oilfield to enhance oil recovery, laboratory experimental researches were carried out. The research results show that the crude oil in the formation of the study area has good swellability, is easily miscible with the injected CO2, and the viscosity of the crude oil is easy to be reduced. The minimum miscible pressure of the reservoirs is about 25 MPa, and near-miscible flooding can be achieved under the current formation pressure. The displacement efficiency of CO2 flooding is relatively high, which can dramatically improve recovery rate. The CO2flooding plan was optimized with numerical simulation, in which a five-spot well pattern and a continuous gas injection method were adopted, and the oil recovery is expected to increase by about 13.37% and the oil displacement ratio of CO2 injection will be about 0.33 t/t. The numerical simulation results provide a theoretical basis for the next field application.

关键词: Yanqi basin, Benbutu oilfield, low-permeability sandy conglomerate reservoir, CO2 flooding, enhanced oil recovery, long core flooding, laboratory simulation experiment, oil displacement mechanism

Abstract: The low-permeability sandy conglomerate reservoirs of Benbutu oilfield in Yanqi basin was developed by water flooding in the early stage. While along with water flooding, the reservoirs were seriously damaged, it was even harder to inject water into the reservoirs and the recovery rate stayed in a low level, therefore, it is urgent to switch flooding agent to further improve the recovery rate. In order to determine the feasibility of CO2 injection in the low-permeability sandy conglomerate reservoirs in Benbutu oilfield to enhance oil recovery, laboratory experimental researches were carried out. The research results show that the crude oil in the formation of the study area has good swellability, is easily miscible with the injected CO2, and the viscosity of the crude oil is easy to be reduced. The minimum miscible pressure of the reservoirs is about 25 MPa, and near-miscible flooding can be achieved under the current formation pressure. The displacement efficiency of CO2 flooding is relatively high, which can dramatically improve recovery rate. The CO2flooding plan was optimized with numerical simulation, in which a five-spot well pattern and a continuous gas injection method were adopted, and the oil recovery is expected to increase by about 13.37% and the oil displacement ratio of CO2 injection will be about 0.33 t/t. The numerical simulation results provide a theoretical basis for the next field application.

Key words: Yanqi basin, Benbutu oilfield, low-permeability sandy conglomerate reservoir, CO2 flooding, enhanced oil recovery, long core flooding, laboratory simulation experiment, oil displacement mechanism