Pore scale multiphase flow experiments in bead packs of variable wettability

Description

The aim of this experimental study is to investigate the impact of wetting characteristics on multiphase flow, sweep efficiency, and residual fluid distribution in unconsolidated porous media. A sequence of oil and water injections was performed on bead packs with uniform porosity and permeability, but different wettability characteristics. Uniform and mixed wet bead packs with varying degree of wettability were fabricated to analyze how the residual saturation profiles and the distribution of fluid phases at the pore scale respond to changes in wettability. X ray microtomography was used to visualize and analyze the fluid distribution in each bead pack at the end of oil and brine injection. It was found that sweep efficiency was high for the uniform, strongly wetting glass bead pack. For the intermediate wet plastic bead pack, we observed evidence of viscous fingering resulting in degenerating sweep efficiency after water injection. In media with mixed wetting surfaces, the spatial distribution of wettability influenced the topology of the saturation profiles and resulted in larger quantities of disconnected fluid blobs. Results also showed that the average blob size was independent of the average residual saturation. In addition, the difference in saturation conditions preceding each injection affected sweep efficiency. The residual saturation after the 1st displacement was higher than the residual saturation after the 2nd displacement. The provided data consists of the raw images and the segmented images of three different samples. The samples were identified by experiment conducted as follows: 1. Experiment I was conducted using a plastic bead pack with a 78.69 mm length. 2. Experiment II was conducted using a mixed wet bead pack consisting of plastic and glass beads. The bead volume fraction in this pack consisted of 42.9 percent plastic beads and 57.1 percent glass beads, with a length of 78.08 mm. We refer to this sample as the glass/plastic bead pack. 3. Experiment III was conducted using two separate bead packs in one core holder. These bead packs were aligned in series, separated by a flow distributor with nylon screens. The bottom bead pack was 44.80 mm long and consisted of glass beads. This bead pack will be referred to as the glass bead pack. The top bead pack was 47.39 mm long and included two types of beads, glass beads and oil wet, coated glass beads. The bead volume fraction in this pack consisted of 50 percent glass beads and 50 percent coated glass beads. This sample will be referred to as the glass/coated glass bead pack.