Reservoir Evaluation and Development ›› 2019, Vol. 9 ›› Issue (6): 51-55.

• Petroleum Engineering • Previous Articles     Next Articles

Effect of CO2 extraction on minimum miscibility pressure

QI Guixue   

  1. Research Institute of Exploration and Development, Sinopec Zhongyuan Oilfield Company, Puyang, Henan 457000, China
  • Received:2019-07-18 Online:2019-12-26 Published:2019-12-30

Abstract:

In order to clarify the effect of extraction on miscible pressure during CO2 flooding and make clear the characteristics of minimum miscible pressure of gas front or after gas sweep, the CO2 extraction rate under different pressure and the distribution characteristics of oil components in the extraction process are studied by the extraction experiments under high temperature and chromatographic analysis. The changes of minimum miscible pressure of extracted oil and residual oil are quantitatively analyzed by the interfacial tension vanishing method. Under the experimental condition of 95 ℃ and 10 ~ 45 MPa, the supercritical CO2 can extract the components of each carbon number of the crude oil, and more than 80 % of the extracted oil is C5-20. The extraction rate of supercritical CO2 and the minimum miscibility pressure of extracted oil and residual oil are positively correlated with the extraction pressure. Under the influence of extraction and pressure, the minimum miscible pressure in the CO2 displacement and migration process is a dynamic value, which reduces in the following order: residual oil, crude oil and extracted oil. The minimum miscibility pressure of extracted oil and residual oil is related to component distribution. The critical components affecting miscibility in formation oil are C5-10 and C26+ components. The study result provides good reference for CO2 miscible displacement design and miscible phase prediction.

Key words: CO2 extraction rate, distribution characteristics of oil components, minimum miscible pressure, formation oil critical component, CO2 flooding

CLC Number: 

  • TE357