Effective gas permeability of Tight Gas Sandstones as a function of capillary pressure – a non-steady-state approach

摘要: Single- and two-phase (gas/water) fluid transport in tight sandstones has been studied a series of permeability tests on core plugs nine the southern North Sea. Absolute (Klinkenberg-corrected) gas coefficients (kgas_inf) ranged between 3.8 × 10−16 6.2 × 10−19 m2 decreased with increasing confining pressure (10–30 MPa) by factor 3–5. Klinkenberg-corrected (intrinsic) were consistently higher factors from 1.4 to 10 than determined water. Non-steady-state (He/water) flow experiments conducted up differential pressures 10 MPa document dynamically changing conductivity for phase, which is primarily capillary-controlled (drainage imbibition). Effective 1.1 × 10−17 2.5 × 10−22 m², corresponding relative permeabilities 0.03% 10%. In early phase nonstationary regime (before establishment steady-state conditions), they may be substantially (>50%) lower. measurements are affected following factors: (i) Capillary-controlled drainage/imbibition, (ii) viscous–dynamic effects (iii) slip flow.