Application of Foam for Gas and Water Shut-off: Review of Field Experience
Authors: Zhdanov Stanislav A. , Amiyan A.V. , Surguchev Leonid M. , Castanier Louis M. , Hanssen Jan Erik 
Published: December 2007

Abstract
This paper gives a critical overview of field experience with the use of foam for improved sweep efficiency and control of produced gas in the Former Soviet Union, in the North Sea and in North America. The field practice demonstrates a wide specter of foam application and reservoir problems which the foam processes can mitigate.
Foam applications are classified as injector and producer treatments for gas and water shut-off. Foam was applied in combination with different recovery strategies such as gas and WAG injection, steam injection, in-situ combustion and waterflooding. The choice of foamer and foam placement strategy are important and depend on the reservoir and type of the problem to address. Many technical failures are explainable by erroneous problem definition.
The novelty of the present overview is that it gives a comparison of foam applications in three different geographical areas with different field histories, constraints and requirements on production handling facilities. The review of foam applications in the Former Soviet Union covers field applications of foam in Russia, Azerbaidjan and Kazakhstan. The paper also discusses interesting field examples, previously unpublished with application of new foam processes including polymer enhanced foam and foam treatment for water diversion and shut-off.

Introduction
The practical oil field experience with foam spans more than 25 years. An examination of the published literature shows a broad range of results, from total technical and economic failure to success. This paper does not report in full our comprehensive literature reviews, but attempts to describe some of the most critical problems encountered during foam field tests, generalize key observations, and suggest possible improvement for the future.

Foam Process
Different classifications of foam field projects can be used. The most useful ones are by the type of gas injected, and by the presumed foam process operative. Six types of foam processes and applications with different injection agents were reviewed (Table 1).
Among the drives (well-to-well methods), steam injection assisted by foam is now a mature technology, routinely applied in many fields. Injection of CO2 combined with foam, tested in some extent (though much less than steam foam) has not met the same success, and is still in the development stage. Interesting foam applications with hydrocarbon gas injection, waterflooding and in-situ combustion in the Former Soviet Union are discussed in more details below.

Steam Foam
Field experience with the use of foam for steam injection improvement was described and selected projects assessed in 1989. A recent paper analyzed in more details the technical and economical aspects of some pilot projects. Even at today's low oil prices, steam-foam technology has matured from development to large-scale commercial application in certain oil-producing regions. Examples of recent developments are given by references [4–18].
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