| Steam injection in the form of cyclic steam stimulation and steamflooding has been highly successful as an enhanced oil recovery technique. This study deals with the mathematical simulation of steam injection processes, with special reference to several phenomena, thus far not considered. These are: thermal upgrading of oil, non-Newtonian oil rheology and injection of foam. In addition, a number of steam injection strategies were studied for bottom water heavy oil reservoirs. One of these is the case of partial penetration in formations containing a bottom water layer. Both steamfloods and cyclic steam stimulation were simulated for partially penetrating wells. Another new feature studied in this work is the case of multiple layer steam injection from a single tubing. For this purpose, a wellbore heat loss model was developed for multiple offtake. It was found that the steam quality can vary considerably in such a case, with the lower zone taking steam of lower quality than the upper zone. Finally, the case of gas injection with steam was also investigated for cyclic steam stimulation. The simulator was also used to simulate a scaled model experiment.; Three-phase, two- and three-dimensional, multicomponent simulators and a wellbore model were developed for the above studies. A fully implicit formulation was employed. The finite difference equations were solved using a block matrix band equation solving algorithm. Thermal upgrading, non-Newtonian flow, and foam injection were incorporated into the mathematical model, using the published experimental data. The purpose here was to show the qualitative effects in each of these cases, rather than a comprehensive study of each of these effects. It was found that if the oil is shear thinning, the oil recovery and oil-steam ratio are likely to increase. Thermal upgrading may lead to a small recovery increase, if long times are involved. Foam was not particularly effective in increasing oil recovery. In this work, the foam was considered as an agent for decreasing gas phase mobility. Injection of natural gas with steam, in cyclic steam stimulation, was found to increase the oil-steam ratio only marginally. |
