A New Blocking Agent for Waterflood Channeling
Authors: Routson Willis G. , Neale Michael , Penton Jesse R. 
Published: December 2007

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Abstract
Severe channeling or bypassing of injection brine is a serious problem in many waterfloods. A new method has been developed employing a gelled polymer to block high flow channels, such as those caused by fractures and extremely high permeability streaks. Law concentrations (0.1% permeability streaks. Law concentrations (0.1% and less) of polymer mixed with an "activator" greatly change the characteristics of the injected brine to a gel-like material which enters high flow channels and adsorbs onto these paths in the formation. The low concentration of chemicals in the brine makes it economical to use large volumes (10,000 to 20,000 barrels) of gel for in-depth treatments. The process is readily compatible with existing field facilities and requires very little special equipment. Normal treatment time is two to three weeks, allowing a great deal of flexibility in tailoring the process to the problem. process to the problem. This report describes the process and includes a case history showing field results. cumulative increase of over 16,000 barrels has been attained in less than two years from a well which was initially producing only 10 to 15 barrels of oil per day. This material, commercially sold under the trademark CHANNELBLOCK*, has been used in many fields with up to 19 wells in one field being treated simultaneously. Fractures, high permeability streaks and undefined channels have been corrected in limestone, sandstone and unconsolidated sand formations. The results in many cases have led to improved waterflooding efficiency and higher profits.

Introduction
Channeling of injected brine into producers of a waterflood operation is a common problem. Irregularities in reservoir structure, which are nearly always present, provide high flaw channels that reduce the efficiency of waterfloods and often make them uneconomical. As a result, a wide variety of materials and techniques have been recommended to correct such problems. These include setting agents, such as silica gel, cement and highly cross-linked polymers; suspended solids, such as walnut shells, leather floc, clay and silica; and permeability modifiers such as oil emulsions. It has been recognized that effective treatment should not simply be local in nature but should extend to considerable distances from the well bore.
Conceptually a gelled polyacrylamide appeared attractive for this use. Gelled polyacrylamide is inherently soft and flexible yet polyacrylamide is inherently soft and flexible yet resistant to flow; the stability of polyacrylamides under reservoir conditions has been polyacrylamides under reservoir conditions has been demonstrated.