A review on measurement of the dynamic effect in capillary pressure

Studies have shown that multiphase flows in porous media are in a transient state with the dynamic effect in capillary pressure. The ignorance of the dynamic effect in capillary pressure might lead to some potential errors in engineering application. In this paper, recent advancements in the measurement of dynamic effect in capillary pressure are reviewed, focusing on the experimental setup, experimental method, and data interpretation method. The measuring technologies are developed both in accuracy and measurement range of porous media and fluids. State-of-the-art measurement technology can measure the dynamic effect in capillary pressure in tight rock and carbonate even with the existence of supercritical fluids. During the measurement process, it is essential to record the pressure difference between the wetting and the non-wetting phases and the in-situ fluid saturation. Besides, the end effect and the rapid change in the pressure at the flowing front need to be prevented. The fluid saturation can be measured through electrical resistivity under various injection pressures, which is applicable to determine the dynamic capillary pressure. The semipermeable elements are particularly the key material for testing the dynamic capillary pressure. Their installation site changes from the ends to the sides of the porous media domain. Additionally, the widely used mass balance-based method is not suitable to obtain the average fluid saturation for less permeable porous media, and calibration is required if the centmid-corrected phase average method and the intrinsic phase average method are used to compute the average dynamic capillary pressure. This paper suggests a reference for the evaluation of multiphase and unsaturated flow in porous media.