Geostatistics Reservoir Description
Reasons for Reservoir Characterization
Oil occurs in rock
pore spaces. This rock is called a reservoir. But not
all the rocks are the same. Some rocks have large pores, some have small ones. Some rocks
have
connected pores and some have unconnected ones. In addition, rock can change dramatically
with depth and areal location.
In order to produce oil in the most economically efficient way, we must know
how the rock and other reservoir properties are distributed. The process of
finding out how the properties are distributed is called reservoir characterization.
Reasons for Using Geostatistics
Reservoir characterization is accomplished by calculating property values between
data points. The sum total of these property values, both data and calculated,
is a property grid.
The reason that we use grids to characterize a reservoir is that grids are
the form of data input that are needed for many types of petroleum industry
software, such as cross section and visualization packages, reservoir flow simulators,
and material balance programs. The properties we are gridding are typically
rock properties, although there is certainly no rule that they must be. For
example, they could just as easily be reservoir fluid properties.
Besides geostatistics, there are a variety of other methods to make reservoir
grids. The three main reasons for using geostatistics rather than other gridding
methods are:
(1)
geostatistics can make more accurate grids than any other gridding method
(2)
geostatistics can quantitatively combine many different types of hard and
soft data
(3) geostatistics can quantify the uncertainty in a reservoir description
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