Experimental investigation of asphaltene precipitation during waterflooding using different aqueous phases

Abstract

ABSTRACT This paper aims to study the effect of different aqueous phases including deionized water (D.W), seawater (S.W), and carbonated seawater (C.W) on oil recovery and asphaltene precipitation during waterflooding in core samples from the Azadegan oil field, Ahvaz, Iran. In this regard, we present the outcomes of a series of coreflood experiments on this local reservoir from different aspects. Besides, a mathematical model using the PC-SAFT EoS was applied at different pressures to predict the asphaltene precipitation area at reservoir temperature. The asphaltene was extracted from crude oil and added to Saltrol® 220 to prepare synthetic oil samples with different asphaltene concentrations of 0 ppm, 500 ppm, and 1000 ppm. In the coreflooding experiments, C.W led to the highest permeability in asphaltene-free oil, while in the presence of asphaltene, S.W showed the greatest permeability. The highest recovery factor in absence of asphaltene was 57% achieved by C.W while the highest recovery factor in asphaltene-containing oil was 52.6% and 50.5% for oil with asphaltene concentrations of 500 ppm, and 1000 ppm, respectively, achieved by S.W injection. These outcomes show that S.W injection is a promising method for enhancing oil recovery in the Azadegan oil field and perhaps other carbonate reservoirs.