A New Approach to Economical Waterfloods
Authors: Homolka George A. , Peacock Robert, A. 
Published: December 2007

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
Laboratory and field studies have shown that bypassing and channeling injection water from injection to production wells can be precisely controlled by the use of a suspension precisely controlled by the use of a suspension of micron-sized particles. The percentage of permeability reduction obtained in this way was permeability reduction obtained in this way was found to be dependent solely on the initial core permeability and the quantity of suspension permeability and the quantity of suspension used. The suspended particles are capable of high-percentage permeability reduction even in very permeable materials. The block produced this manner is uniform throughout the porous zone treated and cannot be dislodged by either forward or reverse flow of water or brine.
Data obtained from 30 injection and over 100 production wells in two oil fields show that this process does, in fact, divert floodwater from old channels to the hydrocarbon-bearing regions of the reservoir. This has resulted in decreased WOR and reversal of production decline curves.

Introduction
There can be no doubt that early water breakthrough is detrimental to the economics of a waterflood operational This is because, after a breakthrough has occurred, a substantial portion of the injection water tends to follow portion of the injection water tends to follow the water that broke through so that it will bypass the hydrocarbon-bearing strata. An over-all result is a decrease in the production of oil and an increase in that of water.
A premature water breakthrough may be caused by several factors. Of these, the most common are horizontal and vertical variation in reservoir permeability, naturally occurring and artificially induced fractures, over-injection of floodwater, and the existence of zones of high water saturation in the reservoir. A premature water breakthrough may be caused by premature water breakthrough may be caused by any of these factors or a combination of them.
In order to prevent, or at least minimize, such premature water breakthroughs, a number of products has been developed for the purpose of products has been developed for the purpose of blocking those portions of the reservoir that preferentially conduct injection water to the preferentially conduct injection water to the producing wells. Some of these products such producing wells. Some of these products such as bentonite or silica flour have an appreciable particle size (100 to 1,000 microns) that makes them very suitable for plugging fractures or vugs in the reservoir. They cannot penetrate far into the reservoir rock itself penetrate far into the reservoir rock itself and alter its permeability. On the other hand, oil emulsions, polyacrylamide solutions and gels have been used with some success as blocking agents.