Laboratory Evaluation of Dynamic Interfacial Tension in SAG Process

In this paper, an experimental technique is developed to study the surfactant alternating CO2 injection (SAG) in carbonate rocks. A series of high pressure high temperature (HPHT) coreflooding tests were conducted to examine the dynamic interfacial tension in crude oil /surfactant systems over a wide range of surfactant concentrations.The effects of various parameters such as surfactant concentration and pressure (in Miscible and Immiscible Pressure) on the dynamicInterfacial Tension (IFT) behavior of system were investigated. The experiments were designed in order to observe the effect of CO2-Foam injection on oil recovery by different surfactantconcentrations.Two water alternating gas (WAG) injection experiments were performed at 15.86MPaand 11.72 MPa, to evaluate the effect of pressure on oil recovery and dynamic IFT at miscible and immiscible condition. The core samples provided from a low-temperature fractured light oil reservoir at 46.1 oC and 1148 mdepth,and were initially saturated with synthetic/fieldbrine, 5000 ppm, and then flooded with live oil to reach the pore water saturation at reservoir condition, 46.1oC and 11.72 MPa. The commercial surfactant used was sodium lauryl sulphate(SLS)as an anionic surfactant.The results obtained from the present study showed that the addition of surfactantinto the system decreases dynamic IFT in crude oil /surfactant systems due to increase in oil recovery.It is also found that the added surfactant is more effective and efficient than the effect of pressure in increasing oil recovery.Also the amount of oil recovery in low surfactant concentration (1000ppm) is higher than that for miscible WAG process. Also, it led to an increase up to 6 percent in the recovery factor in comparison to miscible WAG process. Furthermore, the value of the critical micellar concentration for surfactant-oil system was about 2000 ppm

Keywords:

Dynamic IFT , CMC , SAG , WAG , Processes , Surfactant , Carbonate Rocks