The Phase Behavior Study of Air-Foam Flooding in Changqing Ultra-Low Permeability Reservoirs

For phase change characteristics of air foam flooding in Changing ultra-low permeability reservoirs, using the PVT high pressure physical device, gas chromatograph, studies were injected into the air and the gas-phase oxidation of P-X diagram under reservoir conditions, Phase Behavior of crude oil and air bubbles after numerous contacts. Combined with PVT simulation software and the phase equilibrium model, calculate the critical temperature 424.4 °C and critical pressure 9.85 MPa of crude oil. Results show that: under the same pressure, gas dissolved in crude oil after oxidation is strong in the air. Because the foam system and crude oil emulsification during contact has produced multiple contact oxidation, the effect is less than the air and oil, resulting from oxidation of C2-C6 is relatively small, while the C7-C16 is relatively more, gas phase composition to move closer to the C2-C6 trend is relatively slow, and the oil phase group causes the increase of C7-C16 content has to move closer to the C7+, the occurrence of mixed phase difficulty is air contact many times greater, for the study of miscible flooding, non miscible flooding mechanism and gas injection project design provides important basis.