This paper presents the viscoelastic effect of polyacrylamide solutions on oill displacement in porous media. A mathematical model has been developed for simulating a 1D water and polymer flood experiment. In this model, porous media is assumed to be a bundle of capillary tubes. The oil-displacement mechanism by injection fluid is modeled with the annulus flow of displacing fluid through capillaries, in which residual oil is trapped in central cores of capillaries. The reological flow behavior of the injection fluid is modeled with a power-law equation. The power-law parameters (n and Kt) are measured by a cone-and-plate viscometer. Simulation results are compared with the experimental data. In the case of water flood, simulations are relatively well agreed with them. In the case of polymer flood, simulations are not agreed when polyacrylamide solutions are thought to be pseudoplastic fluids (n<1). Optinum n value is estimated from the matching between experimental data and simulation results. When n value is assumed to be 1.124, the best matching is obtained. The polyacrylamide solutions are thought to have dilatent flow behavior in this polymer flood experiment. As psevious investigations, the viscoelastic effect of polyacrylamide solutions causes dilatant flow through porous media. This effect is thought to make oil-recovery rate faster by sharpenning the configuration of polymer front and bring about high injection pressure in polymer flood.
This paper describes a quasi-two-dimensional numerical model for simulating production performance in the Mobara type water-dissolved natural gas reservoir. The model describes two-phase unsteady flow of gas and water in the reservoir, which is composed of horizontal beds of alternating mudstones and sandstones, assuming that flow of water and gas is taking place vertically (i.e. in one dimension only) in the mudstone and radially in the sandstone. The numerical model is applied to study the effect of initial gas saturation and the relative permeabilities to gas and water in the mudstone on the performance of production gas-water ratio and bottom-hole pressure. It is concluded that the initial gas saturation and relative permeabilities have a major effect on these performances. The results of simulation for production performance in the gas field of the Sencho district show general agreement between the calculated and measured values.