Electrokinetics Assisted Surfactant-EOR to Optimize Mature Waterfloods in AbuDhabi Carbonate Reservoirs

摘要

EOR technologies such as CO2 flooding and chemical floods have gained increased interest due to the decreasing number of new-field discoveries, increasing number of maturing fields and higher oil price. Therefore, promising results have been demonstrated in both lab scale and field pilots. Among the emerging EOR technologies, is the surfactant EOR integrated with the application of electrically enhanced oil recovery (EEOR), which is gaining increased popularity due to a number of reservoirrelated advantages such as reduction in fluid viscosity, water-cut, increased reservoir permeability, reduced HSE concerns and increased targeting of the unswept oil. Core flood tests were performed using carbonate core-plugs from Abu Dhabi producing oilfields which were saturated with medium crude oil in a specially designed EK core-flood setup. Electrokinetics (DC voltage of 2V/cm) was applied on these oil saturated cores while waterflooding simultaneously until the ultimate recovery was reached. In the second stage, the recovery was further enhanced by injecting nonionic surfactant (APG) along with sequential application of EK. This was compared with simultaneous application of EK-assisted surfactant flooding on oil-wet cores. A smart Surfactant-EOR process was done in this study that allowed shifting from sequential to simultaneous Surfactant-EOR alongside EEOR. The experimental results at ambient conditions show that the application of waterflooding on the carbonate cores yields recovery of approximately 42-64% along with an additional 6-14% incremental recovery that resulted upon the injection of non-ionic surfactant. However, there was a further 12-15% recovery enhanced by the application of EK-assisted surfactant flooding, which could be promising for water swept reservoirs. In addition, EK was shown to enhance the carbonate reservoir’s permeability by approximately 11-29%. Furthermore, this process can be engineered to be a greener approach as the water requirement can be reduced upto 20% in the presence of electrokinetics which is economically feasible.