A Simplified Capillary Bundle Model for CO₂-Alternating-Water Injection Using an Equivalent Resistance Method

Table 1

Schematics for fluid distribution pattern during CO₂ and water flooding.

Process	Number	Fluid distribution pattern	Description
CO2 flooding	I		The front edge of the mixed-phase zone does not enter into the throat; the fluid in the throat is crude oil.
	II		The front of the CO2 flooding is not entering the throat, but the right end of the miscible belt has entered the throat and occupied a part of the throat.
	III		The front of the CO2 flooding is not entering the throat, but the right end of the miscible belt has entered the throat and occupied a part of the throat.
	IV		The leading edge of the CO2 displacement has not entered the throat, the volume of the mixed phase is larger than the volume of the throat, and the right end has passed through the throat.
	V		The leading edge of the CO2 displacement enters into the throat, and the right end of the miscible zone passes through the throat.
	VI		The leading edge of CO2 displacement passes through the throat and the throat is filled with CO2.
Water flooding	VII		Water leading edge does not enter the throat.
	VIII		Water leading edge enters the throat.
	IX		Water leading edge passes through the throat.