In the process of illustrating the
primary functions of a reservoir engineer, namely, the estimation of hydrocarbons in place, the
calculation of a recovery factor and the attachment of a time scale to the
recovery; this page introduces many of the fundamental concepts in reservoir
description of the calculation of oil in place concentrates largely on the
determination of fluid pressure regimes and the problem of locating fluid
contacts in the reservoir.
recovery is described in general terms by considering the significance of the
isothermal compressibility of the reservoir fluids; while the
determination of the recovery factor and
attachment of a time scale are illustrated by
describing volumetric gas reservoir
chapter finishes with a brief quantitative account of the phase behavior of
multi-component hydrocarbon systems.
system of reservoirs
is not very uncommonystem‟toffindreservoirsagroup river or in a river and its
tributaries. An example of the former are the dams
proposed on the river Narmada (Figure 7)
and an example of the latter are the dams of the Dam odor Valley project
case of system of reservoirs, it is necessary to adopt a strategy for
integrated operated of reservoirs to achieve optimum utilization of the water
resources available and to benefit the best out of the reservoir system.
the preparation of regulation plans for an integrated operation of system of
reservoirs, principles applicable to separate units are first applied to the
of schedule so developed should then be considered by working out several
alternative plans. In these studies optimization and simulation techniques may be extensively used with the application
of computers in water resources development
gas reservoir engineering is introduced at this early stage in the book because
of the relative simplicity of the subject.
will therefore be used to illustrate how a recovery factor can be determined
and a time scale attached to the recovery.
reason for the simplicity is because gas is one of the few substances whose
defined by pressure, volume and temperature (PVT), can be described by a
involving all three parameters.
One other such substance is saturated
steam, but for oil containing dissolved gas, for instance, no such relation
exists and, as shown in Chapter 2, PVT parameters must be empirically derived
which serve the purpose of defining the state of the mixture.
If none of the terms in the material balance equation can be neglected, then
the reservoir can be described as having a combination drive in which all
of energy contribute a
significant part in producing the reservoir fluids and determining
primary recovery factor.
many cases, however, reservoirs can be singled out as having predominantly one
main type of drive mechanism in comparison to which all other mechanisms have a
the following sections, such reservoirs will be described in order to isolate
and study the contribution of the individual components in the material balance
in influencing the recovery factor and determining the production policy of the
mechanisms which will be studied are:
solution gas drive
gas cap drive
natural water drive
these individual reservoir drive mechanisms will be investigated in terms of:
reducing the material balance to a compact form, in many cases using the
technique of Helena and Odeh, in order to quantify reservoir performance
APPLIED TO OIL RESERVOIRS
- determining the main producing
characteristics, the producing gas oil ratio and water cut
determining the pressure decline in the
estimating the primary recovery factor
investigating the possibilities of
increasing the primary recovery.