Gas–Gas Dispersion Coefficient Measurements Using Low-Field MRI

In Situ CH4–CO2 Dispersion Measurements in Rock Cores

“…A number of approaches have been proposed in the literature to deal with this erroneous contribution (e.g. Honari et al 2015b;Hughes et al 2012;Edwards et al 1968;Rajendran et al 2008).…”

“…The method however assumes that the exit and entry effects are identical and simply additive. Honari et al (2015b) employed MRI to monitor CH4 displacements by CO2 in a model glass bead packing, in the process measuring the evolution in the CH4 concentration along the core length. The in-situ effective breakthrough curve measured at an upstream position was used to estimate the in-situ effective breakthrough curve further downstream with KL as the fitting parameter.…”

“…Whilst core-scale measurements of dispersion are in principle transferable to the reservoir scale, these laboratory measurements are nevertheless notoriously difficult to execute and can suffer from many systematic errors including erroneous contributions to mixing that occur both due to entry and exit effects into the rock core sample as well as in piping to and from the rock core holder. Previously we have applied 1D Magnetic Resonance Imaging (MRI) to quantify such gas-phase CO2-CH4 mixing in-situ in a model glass bead random packing (Honari et al 2015b); here we extend this to actual rock cores at conditions more relevant to the reservoir (supercritical fluids and 100 bar pore pressure versus 45 bar pore pressure). We also complement these dispersion experiments with Nuclear Magnetic Resonance (NMR) T2 relaxometry measurements of pore size occupation by the methane during the core flooding process.…”

Contributed Review: Nuclear magnetic resonance core analysis at 0.3 T

“…Intermediate field magnets are ideal for characterizing bulk fluids, the short probe dead time providing access to fast relaxing spins such as heavy oil components (e.g., waxes and asphaltenes), bound hydroxls on clay suspensions (e.g., drilling mud), 20 or pressurized gases. 21 The inclusion of a 3D gradient set enables robust measurements of diffusion and flow through the application of orthogonal homospoil gradient pulses. 22 An intermediate field magnet is suitable for rapid diffusion measurements 23 and quantitative determination of advective displacements through the flow propagator experiment.…”

“…[37][38][39][40][41][42] These SPI-based imaging sequences are ideally suited to samples with short T 1 and T * 2 relaxation times (where T * 2 is the transverse relaxation due to local field inhomogeneities), including clay-bearing sandstones, and enable quantitative determination of local porosity. [43][44][45] Elsewhere, 0.3 T magnets have been used to compare D-T 2 correlations with permeability estimates calculated from X-ray microcomputed tomography (μCT) images, 46 to image drop shapes for interfacial tension measurements, 47 to monitor cement paste hydration, 48 to measure gas dispersion coefficients, 21 and to conduct clinical investigations of human hands. 49 In the present work, fast imaging techniques drawn from the medical literature are applied to saturated rock plugs with long T 1 and T 2 relaxation times to demonstrate the range of imaging modalities available at this field strength.…”