The dynamics of a thin slug of reacting impurity in plow in a porous medium

An attempt is made to establish the relation between the initial concentrat ion distribution of an impurity in a slug and the asymptotic behaviour of t his distribution under the assumption that the impurity is transported by u niform seepage (rectilinear-parallel or plane-parallel) in a homogeneous po rous medium where sorption and chemical reaction occur. The carrying liquid is assumed to be homogeneous and incompressible and the effect of the impu rity on the flow is ignored (a passive impurity). Problems with localized i nitial conditions, their qualitative properties and self-similar asymptotic forms are studied. The principal step in the evolution of a thin slug of a reacting impurity turns out to be quite simple: a concentration distributi on is close in form to the corresponding distribution in the problem withou t reaction but with a variable amplitude; the evolution dynamics of the amp litude and the pulse width are rather well predicted by the method of integ ral relations. The possibility of using the solutions obtained and of the a pproaches developed to analyse the effect of the absorption of the active i mpurity during the reaction on the effectiveness of increasing the yield of petroleum by the injection of thin slugs of an active impurity is discusse d. (C) 1999 Elsevier Science Ltd. All rights reserved.