Chapter 6 - Fundamentals of Reservoir Fluid Flow

Abstract

This chapter focuses on fundamentals of reservoir fluid flow. Flow in porous media is a very complex phenomenon and as such cannot be described as explicitly as flow through pipes or conduits. In porous media, however, flow is different in that there are no clear-cut flow paths that lend themselves to measurement. The analysis of fluid flow in porous media has evolved throughout the years along two fronts, the experimental and the analytical. The main objective of this chapter is to present the mathematical relationships that are designed to describe the flow behavior of the reservoir fluids. The mathematical forms of these relationships will vary depending upon the characteristics of the reservoir. The primary reservoir characteristics that must be considered include: types of fluids in the reservoir, flow regimes, reservoir geometry, and number of flowing fluids in the reservoir. The chapter also discusses the dimensionless pressure drop technique that can be used to determine one or more of the reservoir properties. Finally, all of the mathematical expressions presented in this chapter require that the wells produce at a constant rate during the transient flow periods. Practically all wells produce at varying rates and, therefore, it is important that to predict the pressure behavior when the rate changes. For this purpose, the concept of superposition states, “Every flow rate change in a well will result in a pressure response which is independent of the pressure responses caused by other previous rate changes.”