Page 26 - Principles of Applied Reservoir Simulation 2E

Chapter 2

Basic Reservoir Analysis

The tasks associated with basic reservoir analyses provide information
that is needed to prepare input data for a simulation study. These tasks include
volumetric analysis, material balance analysis, and decline curve analysis. In
addition to providing estimates of fluids in place and forecasts of fieldwide
production, they also provide an initial concept of the reservoir which can be
used to design a model study. Each of these tasks is outlined below,

2.1 Volumetrics

Fluid volumes in a reservoir are values that can be obtained from a variety
of sources, and therefore serve as a quality control point at the interface between
disciplines. Geoscientists use static information to determine volume in a
process that is often referred to as volumetric analysis [see, for example, Mian,
1992; Tearpock and Bischke, 1991 ]. Material balance and reservoir simulation
techniques use dynamic data to obtain the same information. Consequently, an
accurate characterization of the reservoir should yield consistent estimates of
fluid volumes originally in place in the reservoir regardless of the method chosen
to determine the fluid volumes. In this section, we present the equations for
volumetric estimates of original oil and gas in place.
Original oil in place (OOIP) in an oil reservoir is given by

Ar 7758 (|> Ah S.
N = 2—2!- l (2 1}
j
B

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