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Speaker at Oil and Gas Conferences - Xiliang Liu
China University of Petroleum Beijing, China
Title : The effect of different phase zones distribution on the characteristics of oil production during CO2 flooding process

Abstract:

Both laboratory tests and pilot wells have demonstrated the significant potential of CO2 as an EOR medium. Due to the weak pressure conduction and mass transfer of the CO2-oil system, multiple zones between the injection well and production well are generated in the ultra-low permeability reservoirs. This work aims to explore the characteristics of multiple zones and mechanisms of CO2-EOR, combining the experimental results, core-scale, and field-scale simulation. Long core displacement experiments were conducted under different miscibility pressures with production gas assayed using gas chromatography. When the core-scale simulation matched with the experimental results, the four CO2 fronts, which were used to distinguish different zones, were defined based on pressure, interfacial tension, and CO2 concentration along the long core. The distribution of five zones was upscaled to the field-scale model after the history matching of pilot wells. The final step was to evaluate the value of the miscible zone range, utilization factor of CO2 injection, oil recovery, and CO2 storage efficiency during the CO2 injection process. Results show that the boundary between the original oil zone and the oil transition zone exists at the CO2 component front, where the CO2 concentration is zero. Additionally, the location of the CO2 component front does not overlap with the contact interface of CO2-crude oil, meaning that the dissolution effect of CO2 in the oil transition zone results in the CO2 component front moving farther. Besides, when the formation pressure is higher than the minimum miscibility pressure (MMP), the distance between the CO2 effective phase front and the CO2 effective component front further expands as the pressure increases, enlarging the miscible zone range. The pressure accumulates around the injection well because of slow pressure conduction. When the average formation pressure reaches 1.1 MMP, the miscible zone range is enlarged by 2.7% higher than that of the near miscible flooding (0.92 MMP), leading to a higher rate of oil recovery by 8.6% and a utilization factor of CO2 by 0.14t/t. An increment in pressure yields a slowing migration velocity of the CO2 component front, therefore, the miscible flooding has a breakthrough time of 0.08 PV later, and the CO2 storage efficiency of 1.4% higher than those of the near miscible flooding. It is for the first time that the range of five zones and the characteristics of four CO2 fronts migration is assessed, furnishing an in-depth understanding of the complicated mechanisms and phase behavior in CO2 EOR in the ultra-low permeability oil reservoir. This work contributes to providing significant information for designing an economic and environmental CO2 flooding strategy and is significant in the improvement of oil recovery and the reduction of CO2 emission.
 

 Audience Take Away: 

  • This work contributes to providing significant information for designing an economic and environmental CO2 flooding strategy and is significant in the improvement of oil recovery and the reduction of CO2 emission
  • This work explores the characteristics of multiple zones and mechanisms of CO2-EOR
  • It is for the first time that the range of five zones and the characteristics of four CO2 fronts migration is assessed.
  • This work furnishes an in-depth understanding of the complicated mechanisms and phase behavior in CO2 EOR in the ultra-low permeability oil reservoir
  • This research could be used to expand other faculty research or teaching.

Biography:

Dr. Xiliang studied EOR at China university of petroleum Beijing in 2018. He joined the research group of Fellow of China academic of Engineering Yang Li at China university of petroleum Beijing. My research interests include CO2-EOR and geological storage. As a researcher, I have published Chemical Engineering Journal, Applied Energy, Energy, Fuel, and Energy & Fuels. Besides, I have attended more than 10 projects entrusted by the National Natural Science Foundation of China, the National Key Basic Research Program, and oilfield enterprises and I have awarded 3 provincial level prizes.

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