Отправлено: 23.03.15 16:17. Заголовок: ARE PORE LINING CHLORITES A CAUSE OF LOW RESISTIVITY IN SANDSTONES?

SCA 2001-34
1
ARE PORE LINING CHLORITES A CAUSE OF LOW RESISTIVITY IN SANDSTONES?
François Henn*, Claudine Durand1
**, Adrian Cerepi2
** , Etienne Brosse** and J.C.
Giuntini*

ABSTRACT
Low resistivity in argillaceous sandstone reservoirs may be attributed either to the effect of
microporosity, or to specific effects due to clays and/or to conducting minerals. In the
frame of a study on pore lining chlorite bearing sandstones, from different hydrocarbon
reservoirs, measurements of cation exchange capacities and specific surface areas have
been performed, on whole rocks as well as on size separated fractions. Both sets of values
are low, in agreement with the structural and textural observations. The dielectric
properties, including intrinsic conductivity, of these chlorites have been investigated, on
size separated fractions, as a function of temperature, and compared to that of reference
clays. The results show a large influence of the moisture, current frequency, and
temperature on the electrical properties. The chemical composition and structure of the
clays has an obvious influence as well. However, the range of conductivities is such that
the intrinsic influence of clays on the conductivity of argillaceous sandstone is lower than
that related to the presence of water by several orders of magnitude.