Reservoir Evaluation and Development ›› 2019, Vol. 9 ›› Issue (3): 47-50.

• Field Application • Previous Articles     Next Articles

Effects of CO2 miscible displacement and feasibility study of secondary gas flooding of Taizhou formation in Caoshe oilfield

Chen Zuhua1,Sun Lei2,Yang Zhengmao1,Wang Haimei1,Feng Yang3,Hua Ganlin4   

  1. 1. Exploration and Development Research Institute, East China Company, SINOPEC, Nanjing, Jiangsu 210011, China
    2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China
    3. Yanchang Gas Field, Shaanxi Yanchang Petroleum(Group) Co, LTD., Xi'an, Shaanxi 710075, China
    4. School of Energy, China University of Geosciences, Beijing 100083, China
  • Received:2019-02-02 Online:2019-06-26 Published:2019-07-02


The CO2 miscible flooding project in the Taizhou formation of Caoshe oilfield is one of the most successful CO2 EOR projects in China. The feasibility study on the secondary miscible flooding was carried out to settle the issues of complex remaining oil distribution and severe gas channeling in the later stage after first miscible flooding. The characteristic of microscopic fractal dimension in the CO2 miscible flooding process of real core sample was observed through metalloscope. The remaining oil types attaching to the pore surface of rock took on the forms of thin film and isolated beads. The displacement efficiency of the secondary CO2 miscible flooding was 93.4 %, which was 9.73 % higher than that of the first CO2 miscible flooding. The average residual oil saturation was 30.8 % in sealed coring test, indicating great potential of III formation. A feasible development plan for secondary miscible-phases flooding was proposed to develop the stratified reservoirs at the bottom position. The CO2 injection on the higher position was adopt to suppress gas gravity overlap, and the water alternating gas was applied to slow down the gas channeling. Furthermore, the injection profile was adjusted during the whole process of gas injection. The incremental recovery ratio was estimated to be 8 % ~ 10 %.

Key words: Taizhou formation in Caoshe oilfield, CO2 flooding, first miscible-phases flooding, secondary miscible-phases flooding

CLC Number: 

  • TE357