Page 98 - Introduction to Petroleum Engineering

5

MULTIPHASE FLOW

Single‐phase flow refers to flow of a single fluid phase in rock. Other phases may be
present but are immobile. For example, single‐phase oil flows in undersaturated oil
reservoirs even though water is present at connate water saturation. Multiphase flow
refers to the simultaneous flow of two or more phases in the rock. The presence of
two or more flowing phases in a pore space affects the flow of each phase and also
the interaction between fluid and rock. To understand and manage multiphase flow
processes, reservoir engineers have identified properties that represent the interaction
between fluid phases flowing in the same pore space and the interaction between
rock and fluid phases. Rock–fluid properties and their application to multiphase flow
through rock are introduced in this chapter.

5.1 INTERFACIAL TENSION, WETTABILITY, AND
CAPILLARY PRESSURE

Reservoir rock may contain oil, gas, and water phases dispersed throughout the pore
space of the rock. The total surface area of these phases, including the solid surface
of the rock, is large. As a result, interactions between the rock surface and fluid
phases are important in understanding flow in the reservoir. Two surface properties
affect the distribution of fluid phases in a reservoir: interfacial tension (IFT) and
wettability.

Introduction to Petroleum Engineering, First Edition. John R. Fanchi and Richard L. Christiansen.
© 2017 John Wiley & Sons, Inc. Published 2017 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/Fanchi/IntroPetroleumEngineering