Chapter 7 POLYMER FLOODING R Y E N CAE", DAVID B. BURNETT and GEORGE V. CHILINGARIAN INTHODUCTION One of the promising types of enhanced oil recovery is the use of water-soluble polymers. Their use to improve the sweep efficiency of standard waterfloods has been practiced since the early sixties. Many in the industry, however, still consider that the use of a polymer to augment a waterflood is just an extension of that secondary recovery process. Others insist that it should more properly be labeled as a tertiary recovery process, being considered a step away from simply pumping water through the formation. Regardless of the lable put on the process, the use of a polymer is basically to improve the relative mobility ratios of the oil-water front. During the past 20-25 years many new processes and new polymer forms have been developed to assist the flooding operation. Polymers and other chemical flooding processes have become more sophisticated in recent years. Many organi- zations have ongoing research and development projects dealing with polymers and EOR processes. Thus, one can be assured that as the economical situation permits these newly developed methods will be made available. This chapter covers the currently available polymer products and the field techniques in common use at this time. The chapter is organized into two sections as follows: (1) Polymer products and theory of use (a) description of water soluble polymers (b) properties of polymer solutions (c) mobility control processes (d) wellbore profile control processes (2) Planning polymer flood projects (a) screening tests (b) process design (c) equipment and operations (d) the economics of polymer projects The first section covers a general description of polymers including some polymer chemistry. A few definitions of commonly-used polymer terminology are also given and the basic properties of the polymers are described. The data presented on these properties are taken from published sources and in general represent laboratory-derived numbers. The first section also covers the theory involved in mobility control with commonly used polymers.