Use of micellar dispersions to increase water injection capacity of wells has grown rapidly during the past year. Treatments have been performed in many types of formations in nearly all oil-producing areas. The majority of these treatments have proved highly effective and economical. The purpose of this paper is to review the technology of stimulation with micellar dispersions, and compare theoretical results with those actually achieved. This analysis will attempt to show what factors might affect results, and determine where and how this type of treatment can be used most effectively.
Injection well stimulation with micellar dispersions was first described by W. B. Gogarty, et al, in 1969. During the past year, this service has been commercially available and different types of formations in many areas have been treated by this process. The results of these treatments process. The results of these treatments (Table 1) indicate that micellar solutions can economically and successfully increase injectivity of water input wells. Analysis of the treatments has provided information which is useful in determining how and where these treatments might be used most effectively.
Micellar solutions increase well receptivity to water by removing residual oil from the critical injection area around the wellbore. Removal of this irreducible oil saturation increases the relative permeability to water in the treated area. If all the oil is removed, relative permeability to water becomes equal to absolute permeability or single-phase flow.
Figure 1 is a plot of relative permeability to water and oil versus water permeability to water and oil versus water saturation. This is an actual plot of Bartlesville sand. The solid black lines represent actual plotted values. The dotted lines are extrapolated to show how relative permeabilities would change if varying permeabilities would change if varying percentages of residual oil were removed for percentages of residual oil were removed for the rock. Various formation cleaners and solvent systems are capable of relative permeability changes as indicated by the solid permeability changes as indicated by the solid lines, but only the micellar dispersions so far have been able to effect the changes represented by the dotted lines.
To show effect of the critical matrix on the overall injection rate, a formula can be developed using a cylinder (Fig. 2) where:
rw = well radius
rt = radius of treated matrix