Gas-brine relative permeability data for H₂, N₂, and CO₂ in Buff Berea sandstone at 0.1-6 MPa

Steady-state drainage gas-brine relative permeability measurements for hydrogen (H₂), nitrogen (N₂), and carbon dioxide (CO₂) in a single Buff Berea sandstone core (~164 mD, 5.11 cm × 2.54 cm) at four pressures (0.1, 2, 4, and 6 MPa) and 22 °C, with brine salinity 74,000 mg/L. Each (gas, pressure) condition was measured at 13 fractional-flow steps with two replicates. Independently measured gas-brine interfacial tensions and gas viscosities at each pressure are also included. These data accompany the manuscript "Comparative Gas-Brine Relative Permeability of H₂, N₂, and CO₂ under Subsurface Storage Conditions" by Li et al. (Geophysical Research Letters, 2026), which uses them to develop a unified interfacial-tension-based scaling for endpoint gas mobility, irreducible water saturation, and crossover saturation.