A thorough
knowledge on pore size distribution (PSD) is one of
the fundamental requirements for characterization of shale gas reservoirs
and for accurate estimation of their gas storage potential. However,
being an important future source of energy need in India, the pore
size distribution of Indian shale gas systems is not scientifically
well understood. In the present study, the nanoscale pore size distributions
of prospective Indian shale basins, viz., Cambay, Cauvery, Krishna-Godavari
(K-G), and Damodar valley (DV), were investigated using mercury injection
porosimetry (MIP) and low-pressure gas adsorption (LP-N2 and LP-CO2) techniques. The study focused on identifying
the priority basins for shale gas production which can be substituted
for sequestration of CO2 based on their PSDs. The samples
exhibited higher thermal maturity with increasing organic content.
The chemical composition of the shale samples was inferred from XRD
data, which depicted higher clay content. The prominent clay minerals
identified muscovite, illite, and kaolinite, which are generally flaky
in nature. These minerals contributed significantly to the pore size
complexity of the studied shale samples. The experimental result suggested
that the samples exhibited diversified pore size characteristics.
The shales are chiefly bimodal, consisting of mesopores (2–50
nm) and micropores (<2 nm). The micropores were efficiently accessed
using CO2, while N2 was effective on characterizing
the mesopore region. MIP analysis was used to infer the pore throat
area. The average pore diameter of samples ranged from 3.38 nm in
Damodar valley to 3.94 nm in thr K-G basin, while Cauvery and Cambay
basin samples possessed 3.88 and 3.86 nm, respectively. Both N2 and CO2 adsorption (type II and type I, respectively)
suggested the presence of micropore infilling in all of the basin
samples. However, Cauvery basin samples were inferred with higher
mesopore content as compared to other basins and possessed higher
quartz percentage, making it more appropriate for hydraulic fracturing.
The Cauvery basin showed enrichment of larger pore sizes. The results
signified that the Damodar valley shales have a higher affinity toward
CO2 adsorption. This suggested that the basin could be
a better host for future carbon storage, compared to other basin pore
structures.
Several deformation phases in tectonically active Himalayas have rendered the rock masses very complex in terms of structure, lithology and degree of metamorphism. Again, anthropogenic activities such as roads, tunnels and other civil engineering constructions have led to a state of disequilibrium which in many cases, results in failure of rock masses. National Highway-05 around Jhakri area in India is a major connecting route to the China border in the hilly terrains of the state Himachal Pradesh. It cuts through the Himalayan rocks and has a hazardous history of landslides destroying human lives and interrupting communication very frequently. As a contribution towards the mitigation process, a study has been carried out along the highway to analyse kinematic stability and qualitative estimation of rock mass condition through rock mass classification systems. The kinematic analysis shows that the rock slopes are prone to planar and wedge failure. Rock mass rating for most of the locations lies between 7 and 34, representing a poor rock mass quality (Class IV), whereas slope mass rating is more disperse and ranges from 11 to 52 for most of the slopes (Class III, IV and V).
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