The Areal Sweep Efficiency of the First-contact Miscible Displacements: An Experimental Approach

Abstract

Solvent flooding using the water alternating gas (WAG) technique is very important for predicting the process performance. This technique has been employed in a number of oil fields. However, little data are available in the literature. Therefore, there is an immense need for the sweep efficiency data resulting from first-contact miscible flooding, particularly in view of conducting reservoir simulation studies. In this article, we conducted a series of WAG displacements through glass bead packs. A number of miscible WAG displacement tests were conducted at WAG ratios of 1:1, 1:2, and 2:1. Constant flow rates were used to mask the effects of capillary number on sweep efficiency. Experimental results revealed that the WAG ratio affects the sweep efficiency of the miscible flooding process. In addition, new correlations of areal sweep as function of mobility ratio at various WAG ratios were developed. The data provided can be useful to the oil industry in conducting analytical and numerical modeling studies of miscible WAG processes.

Enhanced Oil Recovery Using Polymer Alternating CO2 Gas Injection: Mechanisms, Efficiency, and Environmental Benefits

“…In the context of the WAG process, studies have highlighted that the optimized injection ratio of water and CO 2 typically falls within the range of 1:1 to 2:1. − Replacing water with a polymer would reduce the amount of polymer required to provide a stable front because of the greater mobility control offered by the polymer. Moreover, higher polymer injection volume per PAG cycle relative to CO 2 is unlikely to substantially impact reducing residual oil saturation because of the severe trapping of oil by polymer .…”