Goldschmidt2018 Abstract
Kerogen Kinetics and Gas Shale
Pore System Analysis of Permian
Shales of Raniganj Field, India
ANNAPURNA BORUAH
University of Petroleum and Energy Studies, Dehradun
The shale gas prospect of organic rich shales were
analyzed for Permian shales including Raniganj, Barren
Measure and Barakar Formation of Raniganj Field, India
using rock eval pyrolysis techniques. The nanometer-scaled
pore systems of gas shale reservoirs were examined using
scanning electron microscopy. To understand the pore system
of these rocks, the total porosity, p ore-size distribution,
organic geochemistry, mineralogy, and image analyses by
were performed. As a tight reservoir, the most of the pores in
shale are micro to nano pores. Compared to conventional
reservoirs, the pore structure of shale presents strong
heterogeneity and anisotropy. Quantitative characterization of
nano-pore heterogeneity and anisotropy is of great
importance for precise calculation of gas reservoir capacity
and the optimization of gas wells layout. A weakly po sitive
trend was observed between the TOC conten t of organic-rich
shales and the quartz content. Both matrix and organic pores
were developed in grey to black shales, as observed by SEM,
along with intergranular pore, interlayer pores, dissolve pores
and fracture pores. Furthermore, with increasing TOC
content, the pore size distribution (PSD) curves of organic-
rich shale showing positive correlation with organic matter
content followed by clay content. Bimodal PSD versus
surface area and unimodal PSD versus pore volume were
analyzed, indicating that surface area is mainly associated
with micropores and fine mesopores (<10 nm) and larger
pores are the chief contributor to pore volume. The po re size
distribution, as interpreted by BJH theory specify that few
samples have larger peak at 4nm (40Aº) to 10 nm (100Aº)
while other samples have limited pores below 20nm (200Aº)
and most of the pores are in the range of 20nm (200Aº) to
55nm (550Aº). BJH adsorption average pore size diameter
ranges from 5.4921nm (54.921Aº) to 29.754nm (2 90.754Aº).
Multiscale transport mechanism of shale gas in micro/nano
slit pores ranging from nanometer to millimeter were studied
by, including different pore types i.e. interlayer,
intergranular, pore and fracture in contact with organ ic
matter, pore and fracture in contact with other types of
minerals, dissolved and micro-cracks. Microcomputer
tomography resolved micropores connected with pore throats
of nano-sized diameters.
Keywords: Shale Gas, Microstructure, Kerogen, Raniganj