Overpressure mechanism prediction based on well log and mineralogy analysis from drill cuttings of well NSE‑001 in the North Sumatra Basin area, Indonesia

Buntoro, Aris and RAHMAD, Basuki and Asmorowati, Dewi and LUKMANA, Allen H and Fattah, Esha Faisal and Anuraga, edo (2022) Overpressure mechanism prediction based on well log and mineralogy analysis from drill cuttings of well NSE‑001 in the North Sumatra Basin area, Indonesia. Journal of Petroleum Exploration and Production Technology. pp. 2801-2815. ISSN 2190-0566

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Abstract

The well NSE-001 is an exploration well located in the North Sumatra Basin, Indonesia, which penetrates several formations
with overpressure zones that have the potential as a drilling hazard in this area. The results of the pore pressure fracture
gradient model show that the response of the wireline log data of well NSE-001 based on the normal compaction trend has
two types of overpressure mechanisms, namely loading and unloading. Rapid sedimentation in the development of the Lower
Baong Formation and Upper Baong Formation as thick and massive shale sequences in the North Sumatra Basin is the main
factor in the generation of an overpressure zone with a loading mechanism. This correlates with the travel time in the sonic
log which is relatively constant with response to the normal compaction trend at depth intervals of 620–1500 mMD (from the
Middle Baong Sand Formation to the Top Gebang Sand Formation). The presence of sillimanite and kaliophilite minerals in
bulk analysis from drill cuttings at depth intervals of 2200–3820 mMD contributed to the generation of hydrocarbon, while
clay analysis showed that the mineral content of kaolinite + illite as alteration product (clay diagenesis) was higher than the
mineral content of smectite. The results of the mineralogy analysis (bulk and clay) correlated with the response of the wireline log
data of
well NSE-001
to
the
normal
compaction
trend,
which
showed
that at
depth
interval of
1500 m
to
3200 mMD

(from
the
Top Gebang Sand
Formation
to
the
Top
Upper Belumai
Formation) is an
overpressure zone
with an
unloading

mechanism,
which
was
characterized
by
luid
expansion
caused
by
clay
diagenesis
and
possibly
hydrocarbon
generation.

Item Type:	Article
Uncontrolled Keywords:	Overpressure mechanism · Well log · Mineralogy · Drill cuttings · North Sumatra Basin
Subjects:	Q Science > QE Geology
Divisions:	Faculty of Engineering, Science and Mathematics > School of Engineering Sciences
Depositing User:	ST., MT HATY INTAN PARAMITA
Date Deposited:	04 Apr 2023 01:32
Last Modified:	05 Apr 2023 01:25
URI:	http://eprints.upnyk.ac.id/id/eprint/33256

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