Determination of Oil/Water Bank Mobility in Micellar-Polymer Flooding(includes associated papers 7668 and 7669 )

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Abstract
This paper discusses how to design the mobility control slug inmicellar-polymer flooding. Total relative mobilities of the oil/water bankin the El Dorado 650-ft Admire sandstone were measured. There were largediscrepancies among the data obtained from different core samples. Datamust be examined carefully for proper design of a slug. Introduction: Because of the high displacement efficiency of micellarsolutions, high water-permeability channels or fingerswould be generated in a reservoir without sufficientmobility control. The low residual oil saturations (0-to10-percent PV) associated with the micellar floodingprocess and high water-permeability channels not onlywould prevent buildup of a stable oil/water bank, but alsowould cause early breakthrough and, therefore, loss of expensive chemicals in the micellar slug. Methods used to design adequate mobility control formiscible-type waterfloods using micellar solutions weregiven by Gogarty et al. Their discussion includes the useof relative-permeability curves, the direct measurementtechnique, and details about the selection ofrepresentative relative-permeability curves. Trushenski el al.presented some interesting results about direct measurementof mobilities of oil/water banks, micellar solutions, andpolymer slugs in laboratory flow experiments using high water-content microemulsions. When determining the mobility design for the ElDorado Micellar-Polymer Demonstration Project, themobility of the oil/water bank in native-state reservoircores was investigated extensively using steady-state andtransient relative-permeability measurements and bydirect determination in micellar-polymer displacementtests. The lowest "minimum total relative mobility" was0.016 cp-1, which corresponds to an apparent viscosityof 62.5 cp for an oil/water bank. The viscosity of the ElDorado crude oil at reservoir conditions is 4.8 cp.Analysis of data resulted in a design mobility of 0.02 cp-1or an apparent viscosity of 50 cp. Total Relative Mobility and Design Mobility: The total relative mobility, lambda T, is defined as the sum of oil and water relative mobilities in a two-phase flow systemit can be expressed by the following equation. (1) Air permeability was used as the basepermeability throughout this study. Viscosities of oilsused in relative-permeability measurements varied from 1.3to 20 cp, depending on the type of oil and temperature.Typical relative-permeability and total relative-mobilitycurves are shown in Figs. 1 and 2. Fig. 2 shows that totalrelative mobilities calculated from relative-permeability data in the direction of decreasing water saturation areconsiderably lower than those calculated in the directionof increasing water saturation. Minimum total relativemobilities (lambda T min) are 0.022 and 0.038 cp-1 in thedirections of decreasing and increasing water saturation, respectively. Imbibition (in the direction of increasingwetting-phase saturation) and drainage (in the directionof increasing nonwetting-phase saturation) commonly are used to describe the direction of saturation change. JPT P. 1055^

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