流动电势和电渗压力的连续测量实验研究及低矿化度下Onsager互易性的验证

Electrokinetic effects, which include the streaming potential and electroosmotic effects, refer to the coupling of fluid flow and electric current due to electric double layer phenomenon at the solid-liquid interface in a fluid-saturated porous medium. Successive measurements of streaming potential and electroosmotic pressure can be used to pick up electrokinetic permeability and verify Onsager reciprocity theorem. In previous studies, core-holders for streaming potential and electroosmotic experiments required different plugs. However, replacing the plugs can result in inconsistent core parameters between the two experiments. In this work, a new core-holder is designed to avoid the replacement of the plugs during the measurement process, ensuring the consistency of the measurement environments between two experiments. We also design a new pressure source, which separates the pressure source and core-holder on two different working platforms, thus suppressing the interference of pressure source noise. Based on the newly designed equipment, 10 sandstone cores saturated with 8 solutions (distilled water, and 0.01, 0.02, 0.05, 0.1, 0.2, 0.4, and 0.6 mol/L sodium chloride solution) are measured. The results show that Onsager reciprocity holds at low salinity. For the case of high salinity, the electroosmotic effect can replace the streaming potential effect in inversion for permeability.