Haines jumps simulation in X-ray CT image of natural sandstone

Abstract

© Published under licence by IOP Publishing Ltd. In this paper, we investigate the effects which are manifested at two-phase drainage flows in porous media at domination of capillary forces - Haines jumps. This pore-scale event is a rapid or burst-like invasion process and is reflected in sharp pressure drop during drainage displacement. This phenomenon was explored in three-dimensional digital model of natural sandstone which was extracted using X-ray computed tomography. For two-phase flow simulation the lattice Boltzmann equations (LBE) were used. The interface interactions between fluids and wetting effects were modeled with color-gradient method in framework of the LBE. We performed an association between pressure drop at Haines jump and direct imaging of corresponding rapid invasion event in 3D model. It was shown that Haines jump occurs at meniscus migration from narrow pore throat to its wide body. The velocity of meniscus displacement exceeds bulk flow rate in more than 100 times and it looks like burstlike invasion. Also, we studied the effects of flow rate and surface tension on Haines jumps statistics. It was revealed that Haines jumps at high flow rates occur simultaneously and individual jumps can't be distinguished on pressure signal. At regimes, where only individual Haines jumps take place, the flow rate influence is insignificant and the distribution of pressure drops can be fitted using lognormal law. Increasing of surface tension leads to growth of mean value of pressure drop and amount of Haines jumps.