Thermal convection in a geothermal reservoir with a caprock was numerically and experimentally studied. The quantitative relations between the average Nusselt number and the coefficient of heat transmission of the caprock, and also the effect of coefficient of heat transmission on convection patterns were determined. It was clarified that the coefficient of heat transmission had some effects on the convection patterns in the reservoir. The theoretical predictions of the average Nusselt number in the reservoir were in good agreement with the experimental results.
One of major problems in applying micellar-polymer flooding to oil reservoir is to determine the most appropriate micellar slug composition for reservoir condition. Generally speaking, micellar slug is composed of oil, brine, surfactant and cosurfactant. The properties of the system are largely dependent on such problems as constituents' types and their proportion of mixture. The major variables we have to consider here are EACN (Equivalent Alkane Carbon Number) of oil, brine salinity, salt type, average molecular weight of surfactant and cosurfactant types together with their combination. Taking into account those variables, phase behavior tests were carried out and also interfacial tensions were measured, of which results are described hereunder. As to phase behavior tests, either of single phase titration or ternary phase diagram tests could be applied. However, in any case, the most favorable result is considered to be the one which has a wide single phase region. In performing the single phase titration, effects of ACN, cosurfactant types and their proportion and divalent cation as well as surfactant blend on optimal salinity were observed. As a result of those courses, a clear prospective could be gained in applying micellar slug to the most optimal salinity. Then the phase diagram tests were conducted and various combinations of some kinds of surfactant and cosurfactant as well as those proportions were observed and thus the ternary phase diagrams were prepared. According to the result of the ternary phase diagram, the most proper mixture condition was obtained by observing height of the binodal curve. (the lower the height of the curve is, the better the system is.) This can be exemplified by the following case. Regarding the interfacial tension, in the case that micellar slug loses its miscibility gradually solubilizing oil and water existing in the reservoir due to miscible displacement and that it consequently results in immiscible displacement, the displacement efficiency becomes higher as the interfacial tension between micellar slug and oil or water becomes lower. Generally, in order to attain the effective displacement, it necessitates lower interfacial tension less than 10-3 dyne/cm. The measurement results of interfacial tensions between separated water or oil and microemulsion within the multi-phase region in the above mentioned ternary phase diagram are given herewith. In conclusion, as a summary of the basic properties in reference to the micellar slug, those results collected from various tests conducted so far are presented regarding correlations between solubility and interfacial tension as well as salinity and Nmin.
Nature of friction factor in vertical two-phase flow, proposed by Poettmann and Carpenter, was examined. The friction factor was correlated with density of mixture. Each of the curves, as shown in Fig. 2 and 3, shows maximum values. The maximum values may be plotted on friction factor-Dρυ curve, drawn by Poettmann and Carpenter. The curve corresponds with bubble flow at Dρυ below 1.0 and with slug flow above 3.0.