Miscible CO2 Simultaneous Water-and-Gas (CO2-SWAG) Injection in the Bakken Formation

Abstract

In this paper, miscible CO2 simultaneous water-and-gas (CO2-SWAG) injection in the tight Bakken formation is experimentally studied. The effective viscosities of high-salinity water and supercritical CO2 mixtures with 12 different water volume fractions are measured at the actual reservoir conditions by using a capillary viscometer. A total of six coreflood tests with four different miscible CO2-EOR schemes are conducted in the tight reservoir core plugs collected from the Bakken formation (Canada). It is found that the measured effective viscosity of the saline water–CO2 mixture increases with the water volume fraction and can be reasonably modeled by using the Arrhenius equation. The coreflood test results indicate that the miscible CO2-SWAG injection with an injected water–gas ratio (WGR) of 1:3 in volume has the highest oil recovery factor (RF). The miscible CO2 water-alternating-gas (CO2-WAG) injection achieves a slightly higher oil RF than that of the miscible CO2 flooding, whereas the waterflooding...