This article was written
especially for "Crain's Petrophysical Handbook"
by E. R. Crain,
P.Eng in 2004. This
webpage version is the copyrighted intellectual
property of the author.
Do not copy or distribute in any form without explicit
Material balance is a numerical approach to calculate
reservoir volume and oil in place. It uses the fluid
properties, pore space compressibility, cumulative
production, pressure changes, porosity, and water
saturation. Some of this information comes from
petrophysical analysis, some from geology and seismic
interpretation, and some from reservoir engineering
investigations, such as PVT analysis of the produced fluids.
The method works best when a reasonable amount of production
has been achieved.
The material below was written by Professor Jon Kleppe,
Department of Petroleum Engineering and Applied Geophysics,
Norwegian University of Science and Technology.