Experimental Study of Upward Oil Migration in a Fracture

Abstract

International audienceThe upward oil migration in a transparent and rough fracture containing a liquid of higher density is studied experimentally using a light transmission technique. The aperture heterogeneity is also measured by light transmission. The injection of oil in a fracture containing a heavier fluid produces a gravitational fingering instability. Depending on the injection velocity (capillary number, Ca) and the density difference between the two fluids (Bond number, Bo), different patterns are observed during the oil displacements. The width of the finger and its velocity are measured as a function of Bo and Ca. A stability analysis of the interface, based on a generalised Darcy equation in a two-dimensional fracture, allows an accurate description of the experimental results. The order of magnitude of the finger width and its velocity are in good agreement with the calculations, with small disparities due to various unknown fluid flow parameters: capillary pressure, finger thickness in the gap of the fracture, finger tortuosity and oil velocity field into the finger. The theoretical approach allows constructing a (Ca, Bo) phase diagram of stability of the interface

Two‐phase flow in rough‐walled fractures: Comparison of continuum and invasion‐percolation models

“…However, when the DNAPL injection rate is increased, simulations with the continuum model show that the invasion pattern changes from single dominant fingers to clusters with numerous tortuous fingers. This trend also shows qualitative resemblance to results from previous experimental observations [ Loggia et al ., ]. Quantitative comparison of the simulation results (e.g., in terms of finger width and fingertip velocity) with the experimental results of Loggia et al .…”

“…Experimental observations by Loggia et al . [] showed that generally with increasing injection rate, the nonwetting phase invasion pattern changes from single tortuous fingers to clusters with numerous tortuous fingers. We used the aperture field shown in Figure a and applied four different injection rates from low to high (from 5 × 10 −7 to 5 × 10 −4 kg s −1 ) on the top boundary.…”

“…According to the phase diagram for stability of displacement presented by Loggia et al . [], the values of Ca and Bo correspond to the gravitationally unstable regime.…”

“…Loggia et al . [] showed that under the influence of buoyancy, two‐phase flow regimes range from tortuous fingers and random clusters to pistonlike displacement with trapping, depending on different combinations of Bond numbers and capillary numbers.…”

Dissolution of dense non-aqueous phase liquids in vertical fractures: Effect of finger residuals and dead-end pools

“…Due to the negligible matrix porosity/permeability the matrix-fracture interaction is not considered here. Additionally, we note that gravity destabilized fingering can be a complex behavior with associated phenomena such as snap-off, fragmentation and pulsation (see e.g., Meakin et al, 1992;Glass and Yarrington, 2003;, Loggia et al, 2009. In this respect, more experimental and modeling studies are needed to understand the fluid displacement and entrapment behavior of a dense organic liquid.…”