Optimizing synthetic core plugs: Sintered glass beads and sand particles for natural rock property replication in fluid flow and reservoir studies

Abstract

Developing reliable synthetic cores that accurately mimic natural rock properties is crucial for studying fluid flow and reservoir processes. This paper presents a novel study for fabricating synthetic core samples by fusing glass beads and sand particles within cylindrical molds. Various synthetic core production and characterization factors were explored, including material selection, fabrication parameter optimization, pore size distribution, and capillary behavior analysis.Ceramic tubes were ideal for core fabrication due to their high-temperature tolerance, durability, and reusability. Quartz glass beads were preferred for their transparency and enhanced heat stability. Varying the size and shape of the glass beads influenced porosity, with round particles having lower porosity and angular particles showing higher porosity. The packing procedure and furnace type affected porosity and permeability, with tightly packed arrangements resulting in lower values. Optimal sintering conditions were identified at 680 °C for 15 min, resulting in high porosity and permeability. Incorporating sand particles at a 1:6 sand-to-glass-bead ratio enhanced core stability under challenging conditions (740 °C), achieving high-pressure resistance (≈15,000 psi) and tighter cores with lower porosity (≈11%) and permeability (≈5 mD) compared to cores made solely of glass beads, which had lower pressure resistance (≈2300 psi) and higher porosity (≈31%) and permeability (≈3190 mD). Synthetic cores demonstrated exceptional stability under fluid flow conditions, with minimal property changes (≈<1%) and wettability alterations comparable to natural cores. The capillary pressure study confirmed the similarity of synthetic cores to real cores, revealing variations in pore sizes and residual mercury saturations.Overall, this innovative study highlights the potential of sintered glass beads for producing better synthetic core plugs. Including sand particles at elevated temperatures and extended retention times enables the production of tighter synthetic core plugs. The findings confirm the essential role of sintered glass beads in replicating natural rock properties and studying fluid flow at reservoir conditions.