The effect of a microscale fracture on dynamic capillary pressure of two-phase flow in porous media. (March 2018)

• Record Type: Journal Article
• Authors: Tang, Mingming; Lu, Shuangfang; Zhan, Hongbin; Wenqjie, Guo; Ma, Huifang
• Is Part Of: Advances in water resources. Volume 113(2018)
• Page Start: 272
• Page End: 284
• Publication Date: 2018-03
• Subjects: Fracture -- Porous media -- Dynamic capillary pressure -- Multiphase flow -- Lattice Boltzmann method; Hydrology -- Periodicals; Hydrodynamics -- Periodicals; Hydraulic engineering -- Periodicals; 551.48
• DOI: 10.1016/j.advwatres.2018.01.015
• Languages: English
• ISSNs: 0309-1708

Abstract

Highlights: Lattice Boltzmann method is used to invest dynamic capillary pressure (DCP) effects. Significant effects of micro scale fractures on DCP are observed. The orientation of micro-fracture will influence DCP coefficient. Abstract: Dynamic capillary pressure (DCP) effects, which is vital for predicting multiphase flow behavior in porous media, refers to the injection rate dependence capillary pressure observed during non-equilibrium displacement experiments. However, a clear picture of the effects of microscale fractures on DCP remains elusive. This study quantified the effects of microscale fractures on DCP and simulated pore-scale force and saturation change in fractured porous media using the multiphase lattice Boltzmann method (LBM). Eighteen simulation cases were carried out to calculate DCP as a function of wetting phase saturation. The effects of viscosity ratio and fracture orientation, aperture and length on DCP and DCP coefficient τ were investigated, where τ refers to the ratio of the difference of DCP and static capillary pressure (SCP) over the rate of wetting-phase saturation change versus time. Significant differences in τ values were observed between unfractured and fractured porous media. The τ values of fractured porous media were 1.1 × 10 4 Pa ms to 5.68 × 10 5 Pa ms, which were one or two orders of magnitude lower than those of unfractured porous media with a value of 4 × 10 6 Pa. ms. A horizontal fracture had greater effects on DCP and τ than a vertical fracture, given the same fracture aperture and length. This study suggested that a microscale fracture might result in large magnitude changes in DCP for two-phase flow.