Отправлено: 18.10.12 04:27. Заголовок: Емкость хлорита из глинистой фракции

Номера образцов олдной коллекции и емкость обмена хлорита из глинистой фракции (различие почти в 10 раз)

LS1 1.9
S1 4.6
D2 9.3
C1-C5 14.4

Effect of Pore-Lining Chlorite on Petrophysical Properties of Low-Resistivity Sandstone Reservoirs
Claudine Durandand Etienne Brosse,IFP, and Adrian Cerepi,EGID

Summary
Chlorite-bearing sandstones usually give low resistivity signals and
are thus erroneously identified as nonpay zones, even if they exhibit
good preserved porosities at depth. The purpose of this paper is to
provide petrophysical and mineralogical laboratory measurements
that help improve the log interpretation of these sandstones.
The main results were obtained from a selection of reservoir
cores. For sandstones having an amount of chlorite between 3 and
11 wt%, they show that the cementation index and saturation expo-
nents ( m and n) have values lower than 2, with n frequently around
1.5. These low values have been checked carefully to avoid exper-
imental artifacts. Cationic Exchange Capacities (CEC) and
Specific Surface Areas (SSA) both have low values, as expected
from the clay structure. The distribution of pore throats is bi- or tri-
modal, with a large contribution of microporosity.
The interpretation suggested by these results is that the amount and
distribution of microporosity associated with pore-lining clay is the key
to the chlorite sandstone electrical behavior. The values of CEC or SSA
are too low to fully explain the low values of the saturation index n.
Use of these low values in log interpretation has the effect of
increasing the interpreted oil in place. Advantages of a multidisci-
plinary approach for better evaluation of such complex argillaceous
sandstone reservoirs is highlighted.


June 2001 SPE Reservoir Evaluation & Engineering 231