Experimental and numerical tools for miscible fluid displacements studies in porous media with large heterogeneities (vol 6, pg 309, 1999)

We present a set of complementary experimental and numerical tools for stud ying miscible fluid displacements in porous media with large scale heteroge neities. Experiments are realized in transparent 2D Hele-Shaw cells allowin g optical observations and in 3D packings of glass beads with an acoustical technique for imaging fluid displacements. Permeability heterogeneities ar e modeled by spatial variations of either the local aperture of the Hele-Sh aw cell or the diameter of the grains used in the packing. The Hele-Shaw ce ll model provides high resolution maps of the invasion front location at re gular time intervals and of the flow lines: the velocity field is determine d by combining these informations. Acoustical images of relative concentrat ion distributions in the 3D packing are in agreement with Hele-Shaw cell da ta and can be obtained in a broader range of experimental situations. Such experiments realized with a stabilizing density contrast between invading a nd displaced fluids demonstrate a strong reduction of the front width at, l ow flow velocities, a similar reduction is obtained at high velocities with a stabilizing viscosity contrast. The technique is also applicable to stud y fluid displacements in natural opaque media. Numerical simulations by a B oltzmann lattice technique using a Stokes-like diffusive term to smooth out the effect of permeability discontinuities provide complementary informati ons. They are shown to give similar results as experiments for same flow pa rameter values and to allow for a fast exploration of a broad range of flui d properties and flow situations.