TITLE:
Characterization of Sandstone Reservoir at Bokor Formation, Kampot Province, Kampong Som Basin, Onshore Cambodia
AUTHORS:
Vechheka Oeur, Chanmoly Or, Chandoeun Eng, Sopheap Pech, Lytheng Thorng, Sreymean Sio, Ratha Heng
KEYWORDS:
Sandstone, Reservoir rock, Bokor Formation, Kampong Som Basin, Depositional Environment, Hydrocarbon Reservoir
JOURNAL NAME:
International Journal of Geosciences,
Vol.14 No.8,
August
30,
2023
ABSTRACT: Kampong Som Basin is a Paleozoic-Mesozoic sedimentary basin
located in southern Cambodia. While the sandstone of the Bokor Formation is
expected to be the reservoir for hydrocarbon accumulation. Hence, this study
aims to define the properties, quality, and factors that control reservoir rock
quality. Sandstones of the Bokor Formation are sampled and analyzed using a
helium porosimeter, nitrogen permeameter, polarized light microscope, and
scanning electron microscope (SEM) to check the porosity, permeability,
minerals, pore geometry, and clay minerals that influence the reservoir
quality. According to the result of petrography analysis described by thin
section, the sandstone samples from Bokor formation are classified as quartz
arenite that composes mainly of quartz, rock fragment, mica-flake, and sericite
with connected and unconnected pores of 50 μm to 500 μm with interparticle pore type. Sandstones in this formation have
porosity values ranging from 6.55% to 13.19%, and permeability values ranging
from 10 mD to 60 mD. The statistics of porosity
and permeability of sandstone reservoirs indicate low porosity and permeability
that are suggested to be fair reservoir rock for hydrocarbon accumulation. SEM
results indicate that there are three types of authigenic clay minerals
involving such as kaolinite, illite, and chlorite. In addition, the pore
geometry, quartz overgrowth, dissolution of quartz and felspar grain filling in
pore space, compaction, replacement diagenesis processes, and cementation
presence of clay minerals are the main controlling factors of the sandstone
reservoir from the Bokor Formation. Furthermore, this area exhibits sedimentary
structures such as planar cross-bedding, cross-bedding, parallel lamination,
normal grading, massive, wavy, and reverse graded bedding, which indicates
these lithofacies may be deposited in shallow marine environments.