Microscale heat and mass transfer characteristics of CO2 flooding in nanotubes of tight oil reservoirs

The mechanism of heat and mass transfer in tight oil reservoirs after CO₂ injection is complex. In this paper, first, a CO₂ transfer model within microscale adjacent nanotubes in tight oil reservoirs is established. Then, the typical heat and mass transfer characteristics of microscale CO₂ in tight oil reservoirs is analyzed, and the influence of grid density on the calculation results is discussed. Finally, the influence of thermal conductivity of tight oil reservoirs on CO₂ physical properties parameters is revealed. Results show that: (a) From the inlet end of the thick nanotube to the outlet of the nanotube, the pressure of CO₂ drops from 3.5 to 3.3697 MPa. (b) When the mesh length is equal to 5 nm, the CO₂ pressure in the thin nanotube drops from 3.5 to 3.3329 MPa, and the CO₂ pressure in the thick nanotube drops from 3.5 to 3.2018 MPa. (c) Organic amines react with CO₂ to form salts, which can seal high permeability layers and cracks, but there is a risk of environmental pollution.