MATERIAL BALANCE
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.