The effects of variations in production rate on ultimate recovery are presented for several different combinations of reservoir description and producing mechanisms. The results were obtained from reservoir simulation studies, and were intended to verify the intuitive concept that every reservoir has some limiting production rate, which, if exceeded, can result in serious losses in recoveries.

Our most sophisticated reservoir engineering tools, i.e. reservoir simulators, invariably indicate little rate sensitivity and frequently predict high ultimate recoveries at higher producing rates. In this paper, we focus on the reasons why this occurs when using standard off-the-shelf simulators that have not been equipped with special features to properly address the rate sensitivity issue. We then examine the factors that affect rate sensitivity, i.e. fingering, oil trapping, pore structure, variations in fluid properties, capillary hysteresis, etc., and concentrate on what a reservoir simulator requires to adequately treat these phenomena. We also demonstrate that when a simulator fulfills these requirements, rate sensitiviy is exhibited in certain instances.

Finally we present examples for water-oil, gas-oil, gas-gas and fractured reservoir systems.

You can access this article if you purchase or spend a download.