An experimental investigation of the IFT reduction & wettability alteration by alkaline and cationic surfactant flooding in a micromodel system

Nowadays investigation of fluid flow Mechanisms in porous media can provide valuable information about fluid flow in microscopic scale. In this study we investigated effective mechanisms of fluid flow for oil recovering using Alkaline and Surfactant flooding process in a five-spot glass-micromodel system. According to literatures, two main mechanisms are more important than others which are Wettability alteration and Interfacial tension (IFT) reduction. The Alkaline- Surfactant (A.S) solutions were used in different concentrations where they constituted of C19TAB as a cationic surfactant & NaOH as an alkaline. According to contact angle results by sessile drop method that cationic surfactant can alter wettability from oil-wet to water-wet, in addition to results of pendant drop IFT measurement method that alkaline is incompatible with cationic surfactant for IFT reduction, it can be concluded that, as alkaline reacts chemically with acidic components of crude oil and generates Sodium naphthenate (soap) in situ. Therefore, it is a kind of anionic surfactant, where the cationic surfactant has opposite level load than oleic soap. In this study we investigated wettability alteration & IFT reduction mechanisms, and determined the CMC of C19TAB & NaOH-C19TAB phases. Also we measured recovery factor for different concentrations of A.S solutions using two methods of flooding as the secondary & the tertiary chemical flooding methods and then we compared the sweep efficiency of A.S solutions together in the both methods of chemical flooding. Finally we have provided the major oil recovery mechanisms of A.S flooding by indication as a schematic in pore scale.

Keywords:

A.S flooding , Intermediate oil , Micromodel , Wettability alteration , IFT reduction