TITLE:
Organic Richness and Organic Matter Quality Studies of Shale Gas Reservoir in South Sumatra Basin, Indonesia
AUTHORS:
Jamaluddin , Fuqi Cheng
KEYWORDS:
Organic Matter, Organic Richness, Shale Gas, South Sumatra Basin, Talang Akar Formation
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.6 No.12,
December
14,
2018
ABSTRACT: Talang Akar Formation is a proven hydrocarbon source rock in South Sumatra
basin. The formation contains dominant shale at the top, with some sandstone
interbeds. Whereas it contains coarse to very coarse sandstone beds at
the bottom. The lower sandstone unit also contains carbonaceous shale and
some coal seams. The geochemical analysis is important to identify a source
rock quality in shale gas. The quality of source rock is determined by richness
of the source rock and type of kerogen. 37 samples were collected from well
cuttings in JML-1 and JML-2 wells. Samples we are received into the laboratories
in the form of well site canned ditch cuttings, bagged ditch cuttings in
various stages of preparation from wet, unwashed to dried, washed; sidewall
cores, conventional cores, outcrop samples. The richness of a source rock can
be defined by the content of organic carbon which is measured as total organic
carbon (TOC). Based on geochemical result of analysis, quantity of
shale hydrocarbon potential is indicated by the TOC value of 0.52 wt% - 6.12
wt% (fair to excellent criteria), with average of shale thickness more than 50
m. Tmax is an indication of the maturation stage of organic material and
Hydrogen Index (HI) is a parameter used to explain the origin of organic
material. HI versus Tmax crossplot was analysed for kerogen type determination
and presence of type II/III kerogen was identified. This study concludes
that the source rock contains abundant humic organic matter that was deposited
in a transitional (Fluvio-deltaic) to marginal marine environment under
oxic conditions.