Abstract:

A common way to investigate in the laboratory the uid displacements and interactions that occur in an oil production field is the use of slimtube experiments. Beyond the relative convenience of the experimental setup, the use of small diameter tubing generally allows fast one-dimensional simulations to be conducted alongside. The purpose of this study is to determine the in uence of nonuniform ow and transverse mixing on oil recovery that still may occur into the slimtube, despite the thinness of the columns used.

In order to conduct this study, slimtube experiments were performed, achieving under laboratory conditions a similar problem that we could then rescale to match real life conditions. Furthermore, beyond the primary goal of characterizing nonuniform ow and its interaction with transverse mixing, the experimental results obtained here will be useful for other studies in which a simulation model results and real experiments will be compared.

In slimtube experiments, early breakthrough may occur due to both gravity segregation and viscous-induced nonuniform flow that will form a tongue or several fingers of injecting uid, by- passing the uid in place. Experiments will show that the conditions of the displacement play a great role on the occurrence of such phenomena. The rst consequence of that will be changes in the composition path, which will be moved on the ternary diagram toward the dilution line that connects the initial and injection compositions. The relative in uence of gravity and viscosity will be shown by varying the dip angle of the column as well as the injection ow rate.

Moreover I will present a theory according to which the counter effect of those fast moving nonuniform uid motions is an increase of the exchange surface area between the injected and the initial uid. Being no more a sharp front orthogonal to the direction of the ow as it is predicted by theoretical models, new surface-dependant mixing phenomena will take place. Because of a greater interface, exchanges between the two mixtures are much larger than they can be expected in "piston like" displacement models. Basic mass balance shows that the gravity/capillary tongue is not moving as fast as previously toward the inlet, therefore delaying the breakthrough time. Even though multi- contact miscible displacement is then harder to achieve, this delay yields better recovery results by closing the displacement back to the piston-like model by smearing out the otherwise fast-moving uid regions.

Another way to consider this problem is to look for the limits of one-dimensional (1D) models to study such slimtube experiments. The fact that length is much larger than any other dimension is often cited as justification for the use of 1D models. The practical purpose of this study is first to get experimental results, to which we can compare the results yield by the simulators, and second to experiment that nonuniform ow may, under certain condition, have to be taken into account due to its consequences on recovery. This will allow a clearer interpretation of slimtube experiments.

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Copyright 2009, Louis-Marie Jacquelin: Please note that the reports and theses are copyright to their original authors. Authors have given written permission for their work to be made available here. Readers who download reports from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the author, Louis-Marie Jacquelin.