Preliminary analyses of synthetic carbonate plugs: consolidation, petrophysical and wettability properties

Abstract

Synthetic plugs are available to understand oilfield properties and the behavior of oil in reservoirs where natural plugs cannot be extracted. Specifically, in cases where it is necessary to reproduce representative mineralogical and petrophysical characteristics from carbonate reservoirs, it is evident that there is a lack of publications focusing on synthetic plug construction. In this work, a methodology to construct synthetic carbonate plugs is proposed using disintegrated carbonate rock with controlled particle size, mixed in different weight fraction, uniaxial compaction with controlled load force velocity, pH, temperature, and bonding materials. Preliminary analysis of consolidation (basic consolidation and consolidation by water immersion test), wettability (contact angle measurements) and petrophysical properties (nitrogen expansion porosimetry measurements and theoretical porosity calculation) are reported in this study to determine which composition of the synthetic samples provides similar properties compared to that expected for natural rocks from carbonate reservoirs. Two compositions are recommended to construct synthetic samples: Composition 1 with a total quantity of 100 g of base material (50% w/w of <20 μm, 50% w/w of 20–74 μm) + 5% w/w of amide wax (relative to 100 g of base material) + 6% w/w (relative to 100 g of base material) of pH 3 hydrochloric acid solution; and Composition 2 with a total quantity of 100 g of base material (50% w/w of 150–300 μm, 50% w/w of 300–600 μm) + 5% w/w (relative to 100 g of base material) of amide wax + 6% w/w (relative to 100 g of base material) of pH 3 hydrochloric acid solution. In addition to the compositions, it is necessary to follow the reported procedure based on the uniaxial compaction with controlled load force (200 kN) and velocity (25 mm/min) and the sample’s drying temperature of 100 °C for 1 h aiming to obtain similar samples. These preliminary results will guide further dedicated petrophysical and wettability analysis to deeply understanding these sample’s properties and enhance the construction of synthetic samples more similar to the natural rocks from carbonate reservoirs.