Publisher Summary The appraisal of a planned project and the evaluation of its economic efficiency are illustrated in the chapter. The basis for any economic considerations is the additional oil that may be recovered as compared to a water flood, and the total cost of investments, chemicals, operation and maintenance. Examples are calculated for a typical five-spot with regard to different oil viscosities. For an example calculation of the economics of a polymer flood, a case with 30 mPa's oil is discussed in the chapter. Though the amount of additional oil that may be recovered is not so high, such a project may be economically worthwhile, as the cost for a polymer slug of lower viscosity is also lower. The production data for the 30 mPa's case that is discussed are explained in the chapter.