Porenraumuntersuchungen ausgewählter Rotliegend Sandsteinproben
Norddeutschlands unter besonderer Berücksichtigung der Porengeometrie.
[The Pore Geometry of Rotliegend Sandstones from Northern Germany]
Abstract: The influence of facies and diagenesis on pore geometry
was examined using Rotliegend sandstone samples. For a core sample from
a Rotliegend gas reservoir and samples out of the Flechtinger Höhenzug
complete data files were established, each describing different aspects
of the pore space composition.
Individual pore data (diameter, perimeter, form factor etc.) were obtained
from specially prepared thin section sequence with the aid of an image
analysis system, using a computer program VIDS V. The image analysis is
primarily statistical in nature, with a vast quantity of numerical pore
space information to be processed.
The geometrical analysis of spatial pore configurations has shown definite
characteristic maxima within the frequency distributions, although the
complete range of pore geometries is present in both materials. These
maxima do not concentrate one specific numerical value, instead they include
a certain range of data, indicating that a dominant size and shape spectrum
is present. The "average pore" of the reservoir rock has got an area of
0-200 µm², a diameter of 40-60 µm, a perimeter of 50-150 µm and a length
of greatest extension of 10-70 µm. In the rock sample "Flechtingen" pore
areas of 0-150 µm², diameters of 0-20 µm, perimeters of 50-125 µm and
length of greatest extensions of 40-60 µm dominate. Since both samples
have got numerically different maxima the data is lithologically specific.
Even with a great variety of sizes, arrangements and connections within
the pore spaces, the composition of the pore system obeys certain statistically
Both samples had similar sedimentary and environmental origins, differences
in the diagenesis however are responsible for the divergent pore systems.
Diagenesis is therefore the dominant pore system forming element. Using
a medical research method known from the analysis of organ structure through
elaboration of Cad-Program enhanced sequential photographs, a three-dimensional
pore network model was constructed in order to demonstrate the statistic
information and to illustrate the differences in the pore system composition.
The result is a model of a multi-layered and complex reservoir rock with
layer-specific productivity in contrast to a sandstone with reduced, homogenous
pore system predominantly used in construction.
Further information about microporosity, pore throat distribution and
geophysical parameters was determined by use of SEM-analysis and Hg-penetration
Paper language: german; german
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