(56f) Laboratory Investigation of Viscoelastic Surfactant for Chemical EOR in High Salinity and High Temperature Carbonate Reservoirs | AIChE

(56f) Laboratory Investigation of Viscoelastic Surfactant for Chemical EOR in High Salinity and High Temperature Carbonate Reservoirs

Authors 

Sultan, A. S. - Presenter, King Fahd University of Petroleum & Minerals
Kamal, M. S., King Fahd University of Petroleum & Minerals
Fogang, L., King Fahd University of Petroleum & Minerals
Viscoelastic surfactants are gaining much attention in the recent years due to their structure. Acquiring dual capabilities of a polymer as well as a surfactant in one composition provides considerable value to chemical EOR. Middle East reservoirs are characterized as high salinity and high temperature that make carbonate reservoirs in this region even more challenging. In this work, a systematic experimental study is carried out to test the applicability of novel viscoelastic surfactant (VES-AGA 97) in enhancing the oil recovery.

Rigorous investigation of VES was performed to determine its potential in improving oil recovery. Screening of VES was carried out using five major evaluation techniques. Thermal stability of VES was determined using TGA and FTIR methods. Interfacial tension (IFT) measurements were recorded using spinning drop tensiometer. 1H NMR and 13C NMR were measured with long-term thermal stability tests performed for 30 days in anaerobic conditions at two different high temperatures. Static adsorption was measured by shaking the crushed powder samples with VES for 24 hours and measuring the changes in concentration of VES. Dynamic adsorption is estimated by performing core flooding experiments at 90oC.

Experimental results with TGA demonstrated that VES was thermally stable and showed high resistance to temperatures up to 250oC. FTIR results indicated good thermal stability with strong bonding between C-H and C=O. Considerable reduction in IFT with VES up to 10-1 mN/m range was observed. Effect of concentration, time and temperature on IFT was evaluated. It was also noted that ultralow IFT was obtained at 50oC and 80oC. 1H NMR showed stability in structure while 13C NMR results showed minor structural changes in the aliphatic region. Static adsorption results gave less adsorption when we had high temperatures compared to low temperatures. Langmuir and BET adsorption isotherm models were utilized to determine maximum adsorption rate. Comparison between both models and experimental results exhibited perfect match. Dynamic adsorption was evaluated using concentration analysis of effluents collected at the downstream from core flooding. Difference between the concentrations of VES at inlet and outlet was measured using total organic carbon analysis. Additional oil recovery of 8% was determined when recovery factor is plotted against pore volumes.