Application of Ultrasonic Waves in Enhancing Oil Recovery in Secondary Recovery Phase

Abstract

Abstract Recoverable oil may often remain trapped after secondary recovery processes due to capillary forces, inapt mobility ratio & heterogeneity in the reservoir. To optimize oil recovery, more oil has to be mobilized using enhanced oil recovery (EOR) techniques that are not always so economical. Use of ultrasonic stimulation in the reservoir is a recent innovation that is scarce in literature. It is less risky and it helps to overcome interfacial tension between oil & water, reduce capillary pressure & aid oil mobilization. This paper presents the use of ultrasonic waves in enhancing oil recovery in the tertiary recovery phase using Niger Delta crude oil. Laboratory experiments were carried out and a 3D model of a reservoir created using the Schlumberger eclipse 2010 simulator to predict the performance of the base (water flooding) was employed. The experimental work was in two folds termed test A and B. The former was performed without ultrasound while the latter involves the use of ultrasound (up to a frequency of 54kHz) in the designed flooding system. The resulting relative permeability data from both approaches were obtained and comparatively analyzed. Using MATLAB, results showed that the use of ultrasound waves in reservoirs (permeability> 20 mD, porosity > 15%) leads to increase in recovery by up to 50%. This increase is due to the ability of the waves to unblock the pores, thus creating larger path for the reservoir fluid to flow. The flooding scheme shows that the use of ultrasonic waves in the porous medium yielded a reduction in the critical oil saturation of 0.09 which represents 25.4% of the residual oil saturation obtained with water flooding scheme. Critical oil saturation values of 0.28 and 0.37 were obtained for the wave stimulation and water flooding schemes respectively. The results also shows connate water saturation of 0.27 at relative permeability to oil of 1 which is typical of the results from a well performed imbibition process.