Contribution of the Steady State Method to Water Permeability Measurement in Very Low Permeability Porous Media

摘要: Very low permeability geomaterials (order of nanoDarcy (10-21  m2 )), such as clay rocks, are interest for many industrial applications including production from unconventional reserves oil and gas, CO2 geological storage deep disposal high-level long-lived radioactive waste. In these last two applications, the efficiency clay, a barrier, relies on their very permeability. Yet, laboratory measurement to water (below 100 nD (10-19 )) remains technical challenge. Some authors (Hsieh et al. , 1981, Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 18 245-252) argue that steady state methods irrelevant due time required stabilize fluxes in media prefer transient technique called pulse decay. This study aims perform compare techniques three samples. Regarding method, high precision pump was used measure flow rate through sample. We show with suitable set-up, method enables us 0.8 (8 × 10-22 ) over period days 2.6 (2.6 × 10-21 one day. While decay test provides only an average estimate comparable duration. Many issues raised tests: determination reservoirs factor, micro leakage effects, initial pressure, 2D mechanical effect. Contrary widespread belief permeability, we direct equipments, can be much faster more accurate than by fact, rock compressibilities result fast propagation pressure wave it cannot argued conditions not reachable reasonable amount time. Still, interesting alternative when is higher 50 (5 × 10-20 ).