1. The document describes a scientific presentation analyzing the depositional environment at two wells, FJ-01 and FJ-02, in Muara Enim, South Sumatra using electrofacies analysis of core samples and geophysical logs. 2. The lithology found at the two wells includes silt, clay and fine sand, with increases in grain size from clay to silt. Gamma ray logs indicate patterns including funnel, serrated and symmetrical shapes. 3. Based on the lithological and electrofacies analysis, the depositional environment at the two wells is interpreted to be a transition from a lower delta plain to a transitional delta plain, based on the delta depositional model of Horne (1979

1. THE 51st IAGI ANNUAL SCIENTIFIC MEETING
M Al Fajrin Khalil Gibran
PT. Bukit Asam, Tbk.
“Interpretation of the Depositional Environment at Wells FJ-01 and FJ-
02 Using Electrofacies Analysis at Muara Enim Location, South
Sumatra ”

2. THE 51st IAGI ANNUAL SCIENTIFIC MEETING
PAPER AUTHOR (S)
Mentor Main Author
*phot
o
*phot
o
M Al Fajrin Khalil
Gibran
Muhammad Dwiki Satrio Wicaksono Muhammad Rizky Tanjung
Co-Author
PT. Bukit Asam, Tbk.
Universitas Sriwijaya ‘17

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Outline
Introduction
Research Metodology
Result
Conclusion
Regional Stratigraphy
Location

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Research Objectives: To determine the depositional environment in the
study area based on core rock samples and geophysical logs.
Introduction
Problem Identification
1. Knowing the lithology of the research area.
2. Knowing the geophysical log pattern in drilled wells.
3. Knowing the interpretation of the depositional environment.

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This analysis describes the depositional pattern of a
depositional environment through a gamma ray log
deflection pattern which illustrates the sedimentation
process and sediment boundaries.
Electrofacies Analysis
General Gamma Ray Response to Variations in Grain Size (Walker, 1992). Coal depositional environment model in delta environment (J.C. Horne et. Al., 1979)
Depositional Environment Model (Horne, 1979)
According to Horne et al. (1979), the depositional
environment is divided into 5 zones, namely Upper
Delta Plain, Transitional Delta Plain, Lower Delta
Plain, Back Barrier and Barrier.

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Coal Depositional Environment Model In Delta Environment (J.C. Horne Et. Al., 1979)
Upper Delta Plain
Transitional Lower Delta Plain
Lower Delta Plain
Back Barier

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Location
Area Maps (DEMNAS, 2021)

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Tersier Pliocen Muaraenim Formation (Shell Mijnbouw,1978)
South Sumatra Basin Arc. (Kamal, 2005).
Berbagai Jenis endapan-endapan terestrial, sering berasal dari deposit kasai.
M4
Lempung tufaan biru kehijauan dan lempung pasiran, beberapa lempung batubaraan cokelat tua. Beberapa
putih dan abu-abu, pasir halus sampai kasar, glaukonit. Lapisan batuapung di daerah Palembang Tengah.
Ketebalan 120 - 200 m. e
M3
Komplek pasir dan lanau. Undeburden terdiri dari lempung biru kehijauan, lempung abu-abu kehijauan dan
abu-abu kecokelatan. Beberapa lapisan-lapisan tipis gampingan dan dolomitik. Lapisan pasir 3-6 meter kira-
kira 40 meter di atasa Seam Mangus dengan beberapa kandungan gas. ketebalan lapisan ini berkisar 100-200 Limnic Brackish
M2
Lempung berwarna coklat dan coklat abu-abu. Coklat, abu-abu, pasir halus sampai sedang, beberapa pasir
berbutir halus hijau keabuan di bagian bawah, ketebalan 40-120 meter. Aktivitas Vulkanik di
ujung basin
M1
Paralic
Lempung coklat keabuan hingga biru keabuan dan serpih pasiran sering marly. Pasir umumnya halus
glaukonut hijau. Beberapa batugamping di daerah Palembang Utara dan beberapa tufaan di bagian
Palembang Selatan.
Umur Formasi Delripsi Litologi Group Seam Pengendapan
ALUVIUM
TENGAH
QUARTER
KASAI
PLIOSEN
MIOSEN
AKHIR
AIR BENAKAT
Pasir coklat dan abu-abu, lempung dan lanau dengan sedikit pasir glukonit. Ketebalan lapisan berkisar 100-200
meter.
MUARA ENIM
Kontinen
Gravel bewarna terang dan pasir tufaan, kadang glaukonit, sering dengan kwarsa kristalin, lempung tufaan
dan Kaolin biru kehijauan terang, batuapung asam, konkresi volkanik dan pasir tufaan. Beberapa lensa
batubra. Ketebalan Formasi berkisar 400 - 1,000 m.
Peningkatan yang
kuat dari aktivitas
vulkanik
Neritik Laut Dangkal
Niru
Jelawatan
Enim
Kebon
Benuang
Burung
Mangus
Kladi
Suban
Petai
Merapi
Regional Stratigraphy

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Research Methodology
The gamma ray log functions to measure the content of
radioactive elements such as Thorium (Th), Uranium
(U), and Potassium (K), while the density log serves to
determine the density of rock.
The core of the borehole is used to describe the
lithology of the rock and interpret how it is
stratigraphically subsurface. This Core sample is
the key to the interpretation carried out.
“Interpretation of the Depositional Environment at Wells FJ-01 and FJ-02 Using
Electrofacies Analysis at Muara Enim Location, South Sumatra ”
ELEKTROFACIE
S ANALYSIS
CORE
DESCRIPTION

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Result
Topography Maps (PTBA, 2021)

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FJ-02
Funnel
Shape
Symmetrical
Shape
Serrated
Shape
Funnel Shape
(Coarsening
Upward)
Serrated
Shape
Symmetrical
Shape
Massive
Siltstone
Litofacies
(Fm)
Serrated
Shape
Elektrofacies
Symmetrical
Shape
Serrated
Shape
Symmetrical
Shape
Blocky
(Sedimentation of
Coal)
Lenticular
Siltstone
Litofacies
(Fl)
Massive
Siltstone
Litofacies
(Fm)
Parallel
Lamination
Sandy
Siltstone
(Shb)
Lenticular
Claystone
Litofacies
(Fl)
Flaser
Structure
Litofacies
(Sf)
Siderite
Nodular
Claystone
Litofacies
(Fns)
Parallel
Laminated
Siltstone
Litofacies
(Shb)
Coal Seam
Kladi
62.00 m
11m
7 m 15m 19m 23m 27m 31m 35m 39m 44m 47m
51m 55m
59m

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3 m 7 m 11 m 15 m 19 m 23 m 27 m 31 m 35 m 39 m
40.70 m
FJ-01
Funnel
Shape
Electrofacies
Lithology
Symmetrical
Shape
Blocky Shape
(Sedimentation of Coal)
Funnel Shape
(Coarsening
Upward)
Serrated Shape
(Agrrading)
Blocky Shape
(Agrrading)
Massive
Claystone
Litofacies
(Fm)
Parallel
Laminated
Sandstone
Litofacies
(Shb)
Lenticular
Claystone
Litofacies (Fl)
Coal Seam
Kladi
Flaser
Structure
Sandstone
Litofacies
(Sf)
Lenticular
Claystone
Litofacies (Fl)
Massive
Claystone
Litofacies
(Fm)
Siderite
Nodular
Claystone
Litofacies
(Fns)

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1
2
The lithology found in the two wells is a variety of of silt and clay
with the presence of carbon elements and the insertion of fine
sand. Where there is an increase in grain size from clay to silt
with sand inserts.
3
The gamma ray patterns found in both wells are Funnel Shape,
Serrated Shape, Symmetrical Shape and Blocky patterns. The
Funnel pattern indicates an Upward Coarsening process, while the
Serrated pattern indicates a massive silt and clay.
Based on lithological and electrofacies analysis, boreholes FJ-01 and
FJ-02 were correlated with the pattern of the depositional
environment by Horne (1979). It can be concluded that the
depositional environment is a transition from a lower delta plain to
a transitional delta plain.
Conclusion

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REFERENCES
Afriani, Yulia, et al. 2000. Determination of Coal Quality Based on
Gamma-Ray Logs, Density Logs And Chemical Parameter Analysis.
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THANK YOU