Determination of Oil/Water Bank Mobility in Micellar-Polymer Flooding(includes associated papers 7668 and 7669 )
Authors: Chang H.L. , Al-Rikabi H.M. , Pusch W.H. 
Published: December 2007

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

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