A NOVEL HYBRID ENHANCED OIL RECOVERY METHOD BY SMART WATER ASSISTED FOAM (SWAF)-FLOODING IN CARBONATE RESERVOIRS

The demand for and supply of fossil-fuel continues to be significant and contributes in the order of 85% to the total energy mix. A major part is delivered by crude oil. Due to the climate change concerns, the prospects of finding new giant oil and gas fields are declining and therefore, enhanced oil recovery (EOR) techniques can be a powerful tool to unlock a significant amount of residual and remaining oil from existing hydrocarbon reservoirs. The ultimate goal of this contribution is to investigate the potential of a newly proposed hybrid EOR method, which combines Smart-water injection and Foam flooding in carbonate reservoirs, known as Smart Water Assisted Foam (SWAF) flooding. The main function of
the SWAF process is to displace crude oil to the production wells by the injection of smart-water (SW) followed by SAG, i.e., an alternating injection of a Surfactant Aqueous Solution (SAS) and Gas. Our designed smart-water has a dual improvement effect on crude oil displacement. It changes the carbonate rock wettability towards more water-wet by altering the surface charge at the rock-fluid interface. At the same time, it improves the stability of the foam film by minimizing the shielding effect of the electrical double layer (EDL). These altered surface charges at both rock-fluid and fluid-fluid interfaces cause that the rock-water interface and the water-oil interface have the same sign, resulting in a stable water and foam film. For a variety of reasons, a water-wet medium is usually more effective in displacing oil and thus enhancing oil recovery.