Subsurface Analysis of Sundaland Basins: Source Rocks, Structural Trends and the Distribution of Oil Fields

SUBSURFACE ANALYSIS OF SUNDALAND BASINS: SOURCE ROCKS, STRUCTURAL TRENDS AND THE DISTRIBUTION OF OIL FIELDS

A THESIS SUBMITTED TO THE GRADUATE SCHOOL IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE MASTER OF SCIENCE BY SWARDHUNI PETHE DR. RICHARD H. FLUEGEMAN- ADVISOR

BALL STATE UNIVERSITY MUNCIE, INDIANA DECEMBER, 2013

Table of Contents

List of Figures ……………………………………………………………………………………………...2

Acknowledgements ………………………………………………………………………………………...4

Introduction ………………………………………………………………………………………………...5

Geology …………………………………………………………………………………………………….8

Basement …………………………………………………………………………………………..9

Tertiary Basins …………………………………………………………………………………...10

Talang Akar Formation ………………………………………………………………………..…11

Air Benakat Formation …………………………………………………………………………..12

Methods …………………………………………………………………………………………………...15

Outline, Data Collection …………………………………………………………………………15

Data Processing …………………………………………………………………………………..16

Results …………………………………………………………………………………………………….18

South Sumatra Basin ……………………………………………………………………………..18

Sunda and Asri Basins …………………………………………………………………………...30

Ardjuna (NW Java) Basin ………………………………………………………………………..38

Discussion ………………………………………………………………………………………………...48

Conclusion ………………………………………………………………………………………………..56

Appendix I ……………………………………………………………………………………………...... 57

Appendix II ……………………………………………………………………………………………….61

Appendix III ………………………………………………………………………………………………69

References ………………………………………………………………………………………………...78

List of Figures

Figure 1 Satellite image of the study area with the wells from Google Earth ...... 7 Figure 2 A simple geological map of Sumatra depicting the position of back-arc basins ...... 9 Figure 3 Structure of the basins and deposition with respect to the deformation of the basement ...... 11 Figure 4 A typical example of the stratigraphic sequence in South Sumatra Basin ...... 12 Figure 5 Comparison between the stratigraphic sequences in the Sumatra and Java Basins ...... 14 Figure 6 2D Structural contour map of the basement (top)- South Sumatra Basin ...... 19 Figure 7 3D Structural model of the top of the basement- South Sumatra Basin ...... 20 Figure 8 2D Structural contour map of the Talang Akar Formation (top)- South Sumatra Basin ...... 21 Figure 9 3D Structural model of the top of the Talang Akar Formation- South Sumatra Basin ...... 22 Figure 10 2D Structural contour map of the Air Benakat Formation (top) , South Sumatra Basin ...... 23 Figure 11 3D Structural model of the top of the Air Benakat Formation- South Sumatra Basin ...... 24 Figure 12 2D Isopach map- between the top of the Talang Akar Formation (upper surface) to the top of the basement (lower surface)- South Sumatra Basin ...... 25 Figure 13 Location map for cross-sections 1 & 2, South Sumatra Basin- South Sumatra Basin ...... 26 Figure 14 Cross section 1- A-A’, N-S, South Sumatra Basin ...... 27 Figure 15 Cross section 2- B-B’, SW-NE, South Sumatra Basin ...... 28 Figure 16 Structural contour map of the basement (top) showing the distances between the wells and the grabens- South Sumatra Basin ...... 29 Figure 17 Structural contour map of the basement (top) - Sunda/Asri Basins ...... 31 Figure 18 3D Structural model of the top of the basement- Sunda/Asri Basins ...... 32 Figure 19 Location map for the cross-sections 1& 2- Sunda/Asri Basins ...... 33 Figure 20 Cross section 1- A-A’, General structural trend of the Sunda/ Asri Basins from SW to NE, Sunda/Asri Basins ...... 34 Figure 21 Cross section 2- B-B’, SW-NE, Sunda/Asri Basins ...... 35 Figure 22 Structural contour map of the basement (top) showing the distances between the wells and the grabens- Sunda/Asri Basins ...... 37 Figure 23 2D Structural contour map of the basement (top), Ardjuna Basin ...... 39 Figure 24 3D Structural model of the top of the basement- Ardjuna Basin ...... 40 Figure 25 2D Structural contour map of the Air Benakat Formation (top)- Ardjuna Basin ...... 42 Figure 26 Location map for cross-sections 1& 2- Ardjuna Basin...... 43 Figure 27 Cross section 1- A-A’, W-E, Ardjuna Basin ...... 44 Figure 28 Cross section 2- B-B’, N-S, Ardjuna Basin ...... 45 Figure 29 Structural contour map of the basement (top) showing the distances between the wells and the grabens- Ardjuna Basin ...... 47 Figure 30 Example of wrench faults from Los Angeles Basin ...... 50 Figure 31 Contour map of the basement from Central Sumatra showing NW-SE trending wrench faults 51 Figure 32 Location map of the South Sumatra Basin showing wrench faults ...... 52 Figure 33 Index map of the NW Java showing the distribution of the wells in the area...... 55 Figure 34 2D Isopach map of the Air Benakat Formation - South Sumatra Basin……………………………………………………..………………………………………………...57 Figure 35 2D Structural contour map of the top of the Talang Akar Formation- Sunda/Asri Basins ...... 58

Figure 36 2D Structural contour map of the top of the Air Benakat Formation- Sunda/Asri Basins ...... 59 Figure 37 2D Structural contour map of the top of the Talang Akar Formation- Sunda/Asri Basins ...... 60 Figure 38 3D Structural model of the top of the Talang Akar Formation- Sunda/Asri Basins ...... 61 Figure 39 3D Structural model of the top of the Air Benakat Formation- Sunda/Asri Basins ...... 62 Figure 40 Location map for cross-section A-A', Sunda/Asri Basins ...... 63 Figure 41 Cross-section 3 A-A', SW-NE, Sunda/Asri Basins ...... 64 Figure 42 3D Structural model of the top of the Talang Akar Formation- Ardjuna Basin ...... 65 Figure 43 3D Structural model of the top of the Air Benakat Formation- Ardjuna Basin ...... 66 Figure 44 Location map for cross section 3 A-A', Ardjuna Basin ...... 67 Figure 45 Cross section 3- A-A’, N-S, Ardjuna Basin ...... 68

Acknowledgements

I would like to express my gratitude to my committee chair, Dr. Richard H. Fluegeman for his constant support and guidance throughout my academic career at Ball State. I would also like to thank my committee members Dr. Jeffry Grigsby and Dr. Kirsten Nicholson for their support and valuable suggestions on my thesis. I am very grateful to Dr. William Ade, for providing me the funding to work on this project and also for his valuable insights.

I want to thank my family and my friend Aneesha Balakrishnan, without whose inspiration, this work would not have been successful.

Introduction

Sumatra is the largest island in Indonesia. On a global scale it ranks 21st (as of 2011) in oil production.

Most of the Indonesia’s oil is produced from the oil fields of Sumatra. Sumatra is a part of the Sunda shelf which has been surrounded by the intensely tectonic margins. As a result, a large number of structural basins have formed on the shelf. These basins act as very good traps for the oil accumulation. Depending upon the exact location of the basin, source rock and reservoir rock formations may vary although they are equivalent in age. In this study the focus is on the Talang Akar Formation, which is the source rock in our study area and the Air Benakat Formation, which acts as a reservoir rock.

The purpose of this study is to verify the Ade observation (Ade, W., pers. comm.) about the oil fields and structural basins of Sumatra. According to the observation, “95% of all commercial oil fields in the region occur within 17 km of seismically mappable mature sedimentary rocks in the producing basins”.

Geophysical data available from this region is being used for the analysis of Sumatra basins. This data is part of the geophysical database of the South East Asia- Pacific region, donated by L. Bogue Hunt; commonly known as the “LBH Database”. It contains physical, lithological, and paleontological logs, seismic sections, structural maps and detailed geological reports of many exploration sites.

Sumatra’s oil is sourced from its mature Tertiary back-arc basins. Owing to the subduction zone on the west of Sumatra, the Sunda shelf underwent extension and rifting, which resulted in the formation of these basins. North, Central and South Sumatra basins are among the major on-shore basins. According to

Koesoemadinata (Koesoemadinata, 1969) the deposits of the initial transgressive sequence have yielded large quantities of oil in Sumatra, especially in South Sumatra. Talang Akar Formation is an important source rock from this sequence. As he has stated, the earliest wells were drilled in the Air Benakat

Formation- part of the regressive sequence- which is a great reservoir for the oil. Among the important offshore basins are the Sunda and Asri basins. NW Java basin area is spread both on and off the shore of

Java. All of these basins have numerous sub- basins or individual smaller oil fields.

In this study of the Sumatra basins, well log data from the LBH database were used. In order to assess the basin structures and the distribution of source rock, 2D structural maps of three different units were created; namely, the Talang Akar and Air Benakat Formations and the basement. Isopach maps provided the variation in the thickness of the deposition. Most of the data used here is from the explorations undertaken before 1980. Thus the status of the wells indicated on the maps may have changed. However, the attempt is made to focus on the areas of known history of production. The validity of the given Ade observation is tested in this study. It is hoped, that the conclusions of this study will help determine the extent of the potential area for exploration, surrounding the producing grabens of the Sundaland basins.

Satellite image of the study area with the wells from Google Earth fromGoogle wells withthe area the study of image Satellite

Figure

Geology

The geology of Sumatra is very complex. It is a good example of subduction-related structural features.

Subduction of the Indian-Australian plate under the Sunda plate and the subsequent tectonics governed the formation of the rift basins of Sumatra and Java. Sediments are deposited in the back-arc basins adjacent to the stable Sunda Shelf (Koesoemadinata, 1969). North, Central and South Sumatra are the three major oil producing basins in Sumatra. Sunda, Asri and NW Java are also very important for their petroleum production. Although the stratigraphic sequence and depths of the basins vary over this entire region, the general geology is constant. As a result of the extension of the Sunda shelf, related to the subduction in the west, back-arc basins were formed between the Mobile belt and the stable Sunda craton

(Clure, 2005). Rifting and subsidence generated many extensive and regional faults. This process resulted in the formation of grabens that were filled with deposits during the Tertiary (Fig. 2). Folding of strata at the end of the Tertiary may have further changed the structural complexity of the basins

(Koesoemadinata, 1969). On maturation these basins became an important site of petroleum generation in

Indonesia. The source rock, Talang Akar Formation, is of late Oligocene to early Miocene age. Whereas the reservoir forming Air Benakat Formation was deposited during mid to late Miocene.

Figure 2 A simple geological map of Sumatra depicting the position of back-arc basins (Barber, Crow, & Milsom, 2005) Basement

Basins in Sumatra and Java are mainly Tertiary, lined by the pre-Tertiary crystalline basement rocks. The basement is comprised of mostly igneous and metamorphic rocks and occasionally sedimentary rocks toward eastern Indonesia, as observed from the well logs. Rifting that resulted in the depositional basins took place during Tertiary. Basement rocks were highly deformed into horst and graben structures. Major rifts were formed trending NE-SW on the Sunda shelf (Clure, 2005)

Tertiary Basins

The rifting phase began in early Tertiary and continued until late Oligocene-early Miocene. During this period, structural grabens were formed and filled by the deposition of fluvio-deltaic sediments (Doust &

Noble, 2008). The major basins contain transgressive and regressive facies that provide the source rocks and the reservoir rocks respectively (Fig. 3).

For the purpose of this project, two formations were studied in particular; Talang Akar and Air Benakat

Formations. These are very important formations in Sumatra and Java. It is a petroleum system where the

Talang Akar Formation is the source rock and Air Benakat Formation is the reservoir. Since there are numerous basins in this region that are separated from each other, different formations or petroleum systems may exist, where the source rocks and the reservoir rocks belong to a different stratigraphic sequence. Therefore to simplify the data, such formations were grouped with the Talang Akar Formation or the Air Benakat Formation, based on their equivalent age.

Figure 3 Structure of the basins and deposition with respect to the deformation of the basement (Barber & Crow, 2005)

Talang Akar Formation (TAF)

Talang Akar was deposited as a transgressive sequence during late Oligocene and very early Miocene. It overlies the basement rocks. In some basins Talang Akar may be underlain by other formations; such as lacustrine deposits of Lemat and Lahat Formations in South Sumatra and Jatibarang Volcanics in

Jatibarang basin of NW Java. Talang Akar is comprised of fluvio-deltaic fine shales and silts as well as sands. Some of the sands deposited in near-shore marine environment are fairly porous and permeable and contain oil in the stratigraphic and fault-related traps (Doust & Noble, Petroleum systems of

Indonesia, 2008). Thickness varies from the basin to basin, but this formation can be as thick as 7000 feet

(2133.6 m) in the deepest parts of the basin. Intermittent coal seams are also found, which may act as a source of hydrocarbons. Lower unit of the Talang Akar Formation is known to produce good quality oil in more quantities than that of the upper unit (Koesoemadinata, 1969). The shales of Menggala and

Pematang Formations from Central Sumatra were included as equivalents to the Talang Akar Formation.

Figure 4 A typical example of the stratigraphic sequence in South Sumatra Basin (Clure, 2005)

Air Benakat Formation (ABF)

The Air Benakat Formation is a thick sequence of sands deposited in a regressive system. It is comprised of several units of marine sandstones from deep to shallow marine environment. Air Benakat was deposited during middle to late Miocene, when the rifting phase was over. Since it was deposited as part of the regressive marine sequence, the shallower deposits of Air Benakat have broader distribution. It is the main reservoir rock in the South Sumatra basin. Its average porosity is about 25% (standard range for a sandstone is 5-25%) which makes it an excellent reservoir rock (Bishop, 2001). In parts of South

Sumatra, the lower Palembang Formation is equivalent to the Air Benakat (Fig. 5). In NW Java Basins, the “Main” and “Massive” intervals of the Cibulakan Formation are equivalents of the Air Benakat

Formation (Fig. 5). The Main and Massive are thick sand deposits as thick as 3000 feet (914.4 m). They

are comprised of the lowstand, transgressive and highstand intervals. Since the shallow marine sediments tend to be coarse, they have better porosity. The lowstand sands have an average porosity of 27% and have a very good reservoir quality compared to the transgressive and highstand sands (Purantoro,

Butterworth, Kaldi, & Atkinson, 1994). The Cibulakan Formation is deposited across Ardjuna and

Jatibarang sub-basins of the NW Java.

Comparison between the stratigraphic sequences in the Sumatra and Java Basins (Doust Basins Java and Sumatra inthe sequences stratigraphic the between Comparison

Figure 2008) &Noble,

Methods

Outline

A vast amount of data is available to us in the form of well logs and seismic sections from various oil fields of Indonesia. They provide us the basement depths and the depths to the rock formations of our interest. This stratigraphic data is combined with the geographical locations to produce the stratigraphic and structural maps. Profiles for the individual wells were created in the geophysical software called

“RockWorks”. It allows us to manage stratigraphical data, the production status of the wells and the location. After determining the UTM coordinates and project dimensions in the software, structural and isopach maps for the entire study area were created. In addition to the maps, several cross sections and 3D structural models were created to understand the basin structure in a better way. The maps, and the cross sections, are useful to analyze the position of producing oil fields with respect to the structural features.

The wells with good show of oil were chosen for drawing the cross sections.

Data collection

The geophysical data on South East Asia is available to the Ball State University’s Department of

Geological Sciences, as the LBH database. It includes topographic maps and subsurface profiles, obtained from seismic, resistivity, gamma ray methods etc., as well as detailed geological reports of several oil fields. The main focus of this study is on south Sumatra and northwest Java, Indonesia. Therefore the data representing the oil fields in Sumatra were chosen specifically. This data set has well logs based on electrical resistivity, gamma ray, spontaneous potential and lithology. These logs are important as they contain the location of the well and the depths of the specific geologic formations.

In order to utilize this data and make meaningful interpretations, it is necessary to create extensive geological maps. RockWorks is a powerful software package that allows such data processing and can handle large databases. A database was compiled in an Excel spreadsheet, including the information such as well location, elevation, total depth. The depths to the tops and bottoms of both Formations (Talang

Akar and Air Benakat) and the depth to the top of the basement were entered manually after the spreadsheet was imported into the software. Appropriate symbols were chosen to indicate the status of the wells in terms of production. Some of the once-producing wells drilled in 70’s and 80’s may not be in production today, but they are in the potentially productive oil fields; hence important. Structure of the basement is important in order to determine the basin boundaries; therefore dry holes were equally important in order to obtain the depth of the basement. Formation tops in all the well logs were not marked. If they were missing, they were determined by comparing those logs with other logs or seismic sections from the same field or basin. Depending on the area or the basin, formation names may vary. In that case, their equivalents from the local stratigraphic sequence were used.

Data Processing

It is important to use the same units for all the maps and figures. Elevation and depths were maintained in feet. The geographical coordinates found on the well logs are in the form of degrees, minutes and seconds. They were converted into the decimal degree (DD.ddddd) using software called Garmin. This is the acceptable format for RockWorks. All the latitude figures for the wells in the southern hemisphere were given a negative value. A spreadsheet containing well name, location, elevation, and total depth, was imported into RockWorks and each borehole entry was attributed with the formation depths and the well’s production status using appropriate symbols. Once all the data were entered into the software, the next step was to convert all the latitude and longitude figures from decimal format into the UTM (meter) system. It was done by a simple inbuilt menu option. Since most of the wells in were located in the south of the equator; UTM zone 48S (S for the southern hemisphere) was assigned to the database. Computing the project dimensions was the last step before creating various types of maps.

Simple menu functions allowed the creation of a variety of maps, such as the structural maps of basement,

Talang Akar and Air Benakat Formations. These maps are based on the given depth measurement of the individual wells. 2D isopach maps are particularly useful when we need to evaluate the thickness of a

Formation. These isopach maps were produced for the Talang Akar and Air Benakat Formations. Since

the Talang Akar overlies the basement in most case; the top of the basement was used as a lower surface to indicate the thickness in the isopach maps of the Talang Akar Formation. This is a good way to observe the sedimentary deposition with respect to the basement structure. Every map contains 1) the well locations that are denoted by their status symbol, and 2) appropriate legend. Vertical profiles or cross sections were also produced to better understand the basement structure. Contour interval (CI) for the structural contour maps and the isopach maps is 500 feet.

The goal of this study is to find out if the oil fields are situated within a 17 km distance from the grabens; therefore, only the producing wells and the wells with a good show of oil were treated as potential fields.

The wells with an unknown status were not considered while measuring the distances, since the information pertaining to the show of oil was unavailable. To measure the distances between the wells and the grabens, structural contour maps of the basement were used. Based on the density of the contours, margins of grabens were determined for every basin. Using Microsoft Excel, percentage and the average number of wells situated within a 17 km margin were calculated.

Table 1 Well status symbols

Symbol Status

Unknown

Dry hole

Oil show

Gas show

Oil & gas show

Oil well

Gas well

Oil & gas well

Suspended oil well

Results

The maps described in the results are very large scale maps. The individual clusters of the wells are actually several smaller oil fields or basins. Fault lines are included in the structural maps and 3D models.

The whole study area has been divided into three separate basin areas; South Sumatra, Sunda/Asri and

NW Java. For the well status symbols used in the maps and the cross sections refer to Table 1 in the

Appendix III. More maps, 3D structural models and cross sections are given in Appendices I and II.

South Sumatra Basin

Figure 6 is a structural map of the basement in South Sumatra Basin area. The depth of the basement based on the data points ranges from 1000 (304.8 m) to 10,000 feet (3048 m) below sea level and more commonly from 3000 to 7000 feet (914.4-2133.6 m) below sea level. Most of the producing wells are situated in the deeper parts of the basin. In the upper half of the map there is a group of wrench faults. The

South Sumatra Basin is deeper towards its south end.

Fault; arrow points the downthrow side

Strike slip

Figure 6 2D Structural contour map of the basement (top), CI= 500ft (152.4m)

Figure 7 gives a better idea of the basement structure. Comparison of Fig. 6 to this 3D model shows that the producing wells are situated in the grabens or on their flanks. Towards the south, the basement is as deep as 10,000 feet (3048 m).

Depth (feet)

Distance (meters)

Figure 7 3D Structural model of the top of the basement

The structure of the Talang Akar Formation in Fig. 8 is consistent with the structure of the basement.

Location of the deep troughs and highs matches in both the maps (Fig. 6 & 8). Comparing these two maps, the thickness of Talang Akar appears to be approximately 1000 to 5000 feet (304.8- 1524 m).

Study of the isopach maps will confirm this observation.

Fault; arrow points the downthrow side Strike slip

Figure 8 2D Structural contour map of the Talang Akar Formation (top), CI= 500ft (152.4m)

Based on the 3D model of the Talang Akar Formation (Fig. 9), general trend of the grabens seems similar to that in Fig. 7. The deep graben in the south, as seen in the structural model of the basement (Fig. 7), appears shallower in Fig. 9; suggesting that it was filled heavily with sediments.

Depth (feet)

Distance (meters)

Figure 9 3D Structural model of the top of the Talang Akar Formation

The structure of the Air Benakat Formation in Fig. 10 is somewhat similar to that of the Talang Akar

Formation in Fig. 8; especially in the lower half of the map. However, Air Benakat does not directly overlie the Talang Akar Formation.

Fault; arrow points the downthrow side Strike slip

Figure 10 2D Structural contour map of the Air Benakat Formation (top), CI= 500ft (152.4m)

In Fig. 11 depth to the top of the Air Benakat Formation varies by 5000ft (1524m).

Depth (feet)

Distance (meters)

Figure 11 3D Structural model of the top of the Air Benakat Formation

This map (Fig. 12) has been created using top of the Talang Akar Formation as the upper surface and basement as the lower surface. In most of the logs that represent the wells in this map, Talang Akar lies directly above the basement. The area represented by purple indicates the thickness of 0 to 1000 feet (0-

304.8 m). These are in fact the deep grabens.

Thickness in feet

Figure 12 2D Isopach map- between the top of the Talang Akar Formation (upper surface) to the top of the basement (lower surface), CI= 500ft (152.4m)

Figure 13 is the Location map of the wells in South Sumatra Basin displaying the section lines A-A’ and B-B’.

A’

Figure 13 Location map for cross-sections A-A’ and B-B’, South Sumatra Basin, Distances in meters

Cross section A-A’ passes through three producing wells from different oil fields. The wells on both ends are situated on the flanks of grabens (Fig. 6); however, the one in the middle is situated in the graben. The isopach map in Fig. 12 clearly shows this middle part of the area where the Talang Akar Formation is thicker. All cross sections in this study exhibit the interpolated surfaces of the Talang Akar Formation,

Air Benakat Formation and the basement. For more detailed stratigraphic column, refer to Fig. 5.

Figure 14 Cross section A-A’, SW-NE displaying the structural trends in Talang Akar Formation (TAF), Air Benakat Formation (ABF) and the basement.

In Fig. 15, note that the producing well in the center of the cross section B-B’ (Fig. 15) is situated where the Talang Akar Formation is shallower than the surrounding area. Also, the well on the right end of the section is a producing well, situated further inside the graben. This elevated structure of the Talang Akar

Formation is clearly visible in the 3D model (Fig. 9) towards east.

Figure 15 Cross section B-B’, N-S displaying the structural trends in Talang Akar Formation (TAF), Air Benakat Formation (ABF) and the basement. Producing wells situated on the flanks of the grabens as well as in the middle of the graben.

In Fig. 16, the contour line of -4000 feet (-1219.2m) was chosen as the graben margin, based on the contour density and basin slope (Fig. 7). The average distance between the oil fields and the nearest grabens is 18.31 km. Out of 36 potential oil fields only 28, i.e. 77.78% of the fields lie within the 17 km distance from the grabens.

Fault; arrow points the downthrow side Strike slip

Figure 16 Structural contour map of the basement (top) showing the distances between the wells and the grabens, CI= 500ft (152.4m)

Sunda and Asri Basins

There are two basins in the following map (Fig. 17). The one on the west is the Sunda basin; while Asri basin is in the NE part of the map. They are controlled by major faults (Doust & Noble, 2008). The producing wells in the Sunda basin clearly lie in the vicinity of the fault-bound grabens.

Fault; arrow points the downthrow side

Figure 17 Structural contour map of the basement (top) - Sunda/Asri Basins, CI= 500ft (152.4m)

The overall shape of the Sunda and Asri basins is visible in the 3D model in Fig. 18. They are separated by a ridge, trending approximately north-south.

Depth (feet)

Distance (meters)

Figure 18 3D Structural model of the top of the basement- Sunda/Asri Basins

Figure 19 is the Location map of the wells in Sunda and Asri Basins displaying the section lines C-C’ and

D-D’.

C’

D’

Figure 19 Location map for the cross-sections C-C’ and D-D’- Sunda/Asri Basins, Distances in meters

Cross section C-C’ in Fig. 20 shows the general structural trend of the basins in southwest-northeast direction. From left to right, the line C-C’ crosses the Sunda and Asri basins. Both basins are very close to each other and have a series of grabens of varying depths. For more detailed stratigraphic column, refer to

Fig. 5.

Cross section -C C’

C C’

Figure 20 Cross section C-C’, displaying the structural trends in Talang Akar Formation (TAF), Air Benakat Formation (ABF) and the basement. General structural trend of the Sunda/ Asri Basins from SW to NE, This is a modeled cross section created by incorporating the depths of the closest wells.

The cross section in Fig. 21 shows that the producing wells are situated on the basement high or flanks of the adjacent grabens. This is also the area where most of the producing wells are located according to the structural map of the basement in Fig. 16.

Cross section -D D’

D D’

Figure 21 Cross section D-D’, SW-NE displaying the structural trends in Talang Akar Formation (TAF), Air Benakat Formation (ABF) and the basement. Location of the wells on the horsts is noticeable.

In Fig. 22, the distances from the nearest graben were measured for several wells on a structural map of the basement, using a measurement function in the RockWorks. On observing the density of the contours, the contour line of -5000 feet (-1524 m) was determined to be the margin of the grabens. There are total

23 potential oil fields in this map. Three of them lie outside the grabens, but within a 17 km margin. The distance of the oil fields from the grabens ranges from 8 to 12.6 km; averaging 10.49 km.

Fault; arrow points the downthrow side

Figure 22 Structural contour map of the basement (top) showing the distances between the wells and the grabens, CI= 500ft (152.4m)

Ardjuna (NW Java) Basin

Ardjuna Basin (Fig. 23) is located in the west of the NW Java Basin area. Wells in this basin are some of the deepest and highly producing in Indonesia. Fig. 23 shows three of the major faults that separate the grabens. Depth to the basement ranges from 3000 (914.4 m) to 9000 feet (2743.2 m) below the sea level.

2D structural map (Fig.23) of the Ardjuna Basin shows that there is a series of grabens trending N-S or

NE-SW and varying in the depth. It continues towards Jatibarang Basin in the east, where more fault bound grabens are situated. From the distribution of the producing wells, the oil fields in this basin occupy the area between these large grabens (Fig. 23).

the the

arrow

;

Fault points downthrow side

, CI= 500ft (152.4m). Note the three faults in in faults thethree Note (152.4m). 500ft CI= ,

(top)

2D Structural contour map of the basement the mapof contour Structural 2D

Figure map. the of thecenter

The number of producing wells increases from blue to green area on the structural map in Fig. 23. As per the 3D model (Fig.24), depth of the basin decreases in the same area. This observation is very similar to that of the Sunda and Asri basins; where the most producing wells are situated on the flanks of the grabens.

Depth (feet)

Distance (meters)

Figure 24 3D Structural model of the top of the basement- Ardjuna Basin

In Fig. 25, depth to the top of the Air Benakat Formation ranges from 1200 (365.76 m) to 4800 feet

(1463.04m) below sea level; although most of the production appears to be in the area (marked in green), where the depth is 2400 (731.52 m) - 3200 feet (975.36 m) below sea level.

the the

arrow

;

Fault points downthrow side

, CI= 500ft (152.4m) 500ft CI= ,

(top)

2D Structural contour map of the Air Benakat Formation Benakat Air the mapof contour Structural 2D

25 Figure

Figure 26 is the location map of the wells in Ardjuna (NW Java) Basin displaying the section lines for the cross sections E-E’ and F-F’

E E’

F’

Figure 26 Location map for cross-sections E-E’ and F-F’- Ardjuna Basin, Distances in meters

In Fig. 27, there is a gradual change in the depth of the basement and it becomes shallower from west to east. The alignment of the three faults (Fig. 22), marked by the change in the depth is apparent in the cross section (Fig. 27).

E’

at Formation (ABF) and the and (ABF) Formation at

displaying the structural trends in trends thestructural displaying

, W ,

E’

Cross section E section Cross

Cross section section Cross

. The wells are located between the faults. the between located wellsare The .

Talang Akar Formation (TAF), Air Benak Air (TAF), Formation Akar Talang Figure basement

Figure 28 is displays the structure of the Ardjuna basin in north-south direction. The drop in the basin depth is consistent with that in the structural map of the basement (Fig. 23) and the 3D model (Fig. 24).

The well in the middle has a good show of oil and it is situated where the basement is higher than the areas immediately next to it.

Cross section -F F’

Figure 28 Cross section F-F’, N-S displaying the structural trends in Talang Akar Formation (TAF), Air Benakat Formation (ABF) and the basement. The producing well in the middle of the section is situated on the flank of the graben, as seen in the structural contour map of the basement (Fig. 23). On the left of section F-F’, ABF is interpolated by the software and crosses the TAF; however, it is absent in that location and has an onlap.

In Fig. 29, the contour line of -5000 feet (-1524 m), seen as a break between yellow and green colors, was established as a margin for the grabens. Wells PSI Z, PSI PZ, Dempo 1, Rinjani and Soputan are not part of the Ardjuna basin; however, they were included to provide a better perspective of the area. The distance between the producing wells and the graben ranges from 0.5 to 20.6 km, with an average of

10.12 km. Out of 47 potential oil fields, 43, i.e. 92% fields are situated within 17 km from the grabens.

the the

arrow

;

Fault points downthrow side

Structural contour map of the basement showing the distances between the wells and the grabens, thegrabens, and wells the between thedistances showing thebasement of map contour Structural

29 CI= 500ft (152.4m) 500ft CI= Figure

Discussion

As evident from the maps, the wells are concentrated inside or around the basins; especially the ones that have production potential. Basins on the Sunda Shelf are roughly NE-SW oriented and are fault bound.

Folding of the Sunda Shelf on the east of the Subduction zone has generated numerous small and large faults that are parallel to the strike of folding.

Concentration of the data points in parts of the maps makes the basins appear merged. To resolve this problem, the maps were broken down in several separate regions; focusing on a small slice of the longitudinal area at a time. The first section comprised of the South Sumatra Basin (Fig. 6). The second section contains the Sunda and Asri Basins (Fig. 17) while the third section includes the NW Java Basin area (Fig. 23). Results obtained this way contain more defined basin boundaries and more pronounced structural features.

Structural basins of Sumatra and Java are fault basins. Most of the producing basins of this region lie northeast of the mobile belt. Important producing wells of Sumatra and Java are in the central and south

Sumatra, Sunda, Asri and Northeast Java basins. The Talang Akar Formation is a major source of petroleum in the basins of Sumatra. These fine shales are deep seated fluvio-deltaic sediments that were deposited during the rifting phase (mid Eocene- early Miocene) of the Sunda craton (Doust & Noble,

Petroleum systems of Indonesia, 2008). In central Sumatra they are replaced by the Brown Shale Member of the Pematang Formation. In the basins of NW Java, the reservoir rocks equivalent to the Air Benakat

Formation are the Main/ Massive sands of the Cibulakan Formation. When the rifting phase was over, the deep grabens were heavily filled in by marine sediments (Purantoro, Butterworth, Kaldi, & Atkinson,

1994). In off-shore Java basins on the shelf, a thick marine sequence of the Air Benakat/ Cibulakan

Formations acts as a very good reservoir rock.

South Sumatra Basin

Although wells with a good show of oil are situated in the deeper parts of the South Sumatra Basin; several producing wells are situated on the flanks of the grabens and on the horsts (Fig. 6 &15).

Correlation of these wells with other wells in the same or adjoining fields shows that the sequence of deposition and age of the formations are equal. Therefore, it is evident that the faulting or uplifting occurred after the sediments were deposited in the respective basins. This observation can be supported by the fact that the Talang Akar Formation was deposited during the ‘postrift’ phase when the region was undergoing tectonic movements and structural changes (Doust & Noble, 2008).

A paper by T. P. Harding, “Petroleum Traps Associated with Wrench Faults” (Harding, 1974) talks about the importance of wrench faults in petroleum trap formation. In a region influenced by high tectonic activity, intense folding and faulting produces very complex structures such as wrench faults. The complexity of these structures is due to their intersecting strike-slip, normal and reverse faults. Due to this, the rock strata are offset and the structural traps are formed. Comparing the folds, faults and the basin structures in Sumatra to this model, the wrench faults appear to be a common feature in the basins of Sumatra.

Maps of various oil fields in central and south Sumatra indicate the position of oil fields dispersed in between the wrench faults. These faults are situated on the eastern side of the geanticlinal belt that runs along the length of Sumatra. This folding of the pre-Tertiary and Tertiary rocks and the subsidence of basins could be part of the developmental history of these wrench faults. Fig. 30 is an image from the literature (Harding, 1974) that represents a typical wrench fault system from the Los Angeles Basin. The fault structures in this image are similar to those from the structural map (Fig. 31) from the database and location map of the South Sumatra Basin (Fig. 32). This correlation provides a clue to the possible location for the exploration.

Figure 30 Example of wrench faults from Los Angeles Basin (Harding, 1974). Notice the intersecting faults.

Figure 31 Contour map of the basement from Central Sumatra showing NW-SE trending wrench faults from LBH database.

Depth in feet

Fault; arrow points the downthrow side Strike slip

Figure 32 Location map of the South Sumatra Basin showing wrench faults

Another paper (Ryacudu, Djaafar, & Gutomo, 1992) states a similar observation about the North Sumatra

Basin. The wrench faults in this basin provide a path of migration for oil. These papers and the study of the structural maps from the LBH database, suggest that the wrench faults form good structural traps.

Therefore, more emphasis should be given on identifying the wrench faults during future exploration.

The deposits of the Talang Akar Formation lie deep into the grabens directly above the basement rocks; except when it is underlain by Lemat/ Lahat Formations. Therefore, in the isopach map of the Talang

Akar Formation (Fig. 12), areas of less thickness represent the grabens. Oil fields often coincide with these areas. In the structural map of Air Benakat Formation the producing oil fields fall into an area where

Air Benakat Formation is shallow, i.e. approximately -3000 to -5000 feet (914.4-1524 m). Shallower depth makes it easy to access the reservoir due to which the earliest production came from the shallower wells (Koesoemadinata, 1969).

Sunda and Asri Basins

Figure 17 is a contour map of the basement from the Sunda and Asri Basins. The two basins are bound by faults on their eastern flank. The map and the 3D model (Fig. 18) of the basement give a clear understanding of its structure.

The Sunda and Asri basins are situated in a wedge between Sumatra and Java islands. As of 1997 the oil reserves of these basins were expected to be 1500 MMbo (Doust & Noble, 2008). There are closely spaced grabens up to 7000 feet (2133.6 m) deep, clearly seen in the 3D model (Fig.18). Based on the well data, the source rock- reservoir system in these basins appears to be Talang Akar- Air Benakat/ Batu Raja.

Batu Raja is a reef formation that acts as a good reservoir at many sites in Sumatra- Java. Cross sections

(Fig. 20 & 21) constructed through Sunda/ Asri neatly display the location of wells in relation to the structure of the grabens. Most of the producing wells are located on the flanks, in shallow areas of the grabens. This observation is consistent with previous research in the Sunda and Asri basin area (Doust &

Noble, 2008). The average distance between the wells and the producing grabens is 10.49 km; which is within the 17 km margin described in the Ade observation.

Northwest Java Basin Area- Ardjuna Basin

Another example of a typical structural basin on the Sunda Shelf is the Northwest Java Basin area. The

LBH database contains a large amount of well data from this area. Ardjuna and Jatibarang are the major basins in the northwest Java area. Oil fields in the western part of this area belong to the Ardjuna Basin

(Doust & Noble, 2008). The source rock in Ardjuna Basin is Talang Akar. In the NW Java area, Talang

Akar Formation is underlain by Jatibarang volcanics (Atmadja & Noeradi, 2005). Well logs show that in some of the sections, the Talang Akar Formation contains layers of coal which is an important source of

hydrocarbons as found in south Sumatra basin area (Davis, Noon, & Harrington, 2007). Although Air

Benakat Formation is not present in this basin area, its equivalent Main/ Massive sands act as reservoirs.

These are thick sands deposited during the marine regression. Lowstand intervals of the Main sands have good porosity and permeability which make them good reservoir rocks (Purantoro, Butterworth, Kaldi, &

Atkinson, 1994). Well logs indicate a good show of oil as well as gas in the Main and Massive sands.

These sands can be as thick as three thousand feet. The clusters of wells occur between the N-S and NE-

SW trending series of faults. Jatibarang basin is slightly east of the Ardjuna basin. These sand units also occur in the Jatibarang basin of NW Java. Here they are part of the Cibulakan Formation and given as the upper Cibulakan Member in the well logs. As these sands were deposited toward the end of regression, they are thinner toward the basin walls. This affects the resulting structural and isopach maps where the grabens do not appear prominent. This error was compensated by manually constructing the fault lines based on the available maps from the literature and database (Doust & Noble, 2008).

Figure 29 is a structural map of the basement for the Ardjuna basin. The segments were drawn to measure the distance between the wells and the margins of the nearest grabens. As mentioned in the results, the average of this distance is 10.12 km. It is less than 17 km and thus, concurrent with the Ade observation.

The actual number of oil fields and producing wells is greater than the number of wells shown in the structural map (Fig. 29). That could have lowered the percentage of wells occurring within the 17 km margin. Figure 33 is an index map of the northwest Java, showing the distribution of wells in the area. A large number of those wells are producing wells. Hence, the actual percentage of producing fields within

17 km from the grabens could be equal to or greater than 95, for the Ardjuna Basin.

of the wells in the area. the in wells the of

Index map of NW Java showing thedistribution showing Java of NW map Index

33 Figure

Conclusion

In the South Sumatra Basin, 77.78% of the oil fields are located within 17 km of the producing grabens; with an average distance of 18.31 km.

In the Sunda and Asri Basins, all of the oil fields occur within 17 km distance from the producing grabens; with an average distance of 10.49 km.

In the Ardjuna Basin area of the northwest Java, 92% of the oil fields lie within 17 km of the producing grabens; with an average distance of 10.12 km.

The results of this study indicate that the Ade observation, “95% of all commercial oil fields in the

Sumatra region occur within 17 km of seismically mappable structural grabens in the producing basins” is true for the Sunda/Asri Basins. Given the high percentage of data being in the hypothesized distance range, further study of the individual oil fields and recent data may yield similar results for the Ardjuna

Basin. The well data used for the South Sumatra Basin in this study is not uniformly distributed. Hence, definite conclusions as to what factors control the regional structures, cannot be drawn. Therefore, it is necessary to study the individual oil fields using seismic surveys and well data in order to establish a relationship between the structural features and the oil production.

The structural maps and cross sections indicate that the flanks of the grabens or the horst region may prove to be the potential sites for future exploration. Comparison between the obtained maps and those from the literature suggests that the wrench faults provide good oil traps and may be the potential sites for the exploration as well.

Appendix I: Structural and isopach maps

South Sumatra Basin

Thickness in feet

Figure 34 2D Isopach map of the Air Benakat Formation, CI= 500ft (152.4m)

Sunda/ Asri Basins

Fault; arrow points the downthrow side

Figure 35 2D Structural contour map of the Talang Akar Formation (top), CI= 500ft (152.4m)

Fault; arrow points the downthrow side

Figure 36 2D Structural contour map of the Air Benakat Formation (top), CI= 500ft (152.4m)

the the

arrow

;

Fault points downthrow side

, CI= 500ft (152.4m) 500ft CI= ,

(top)

Basin

)

NW Java NW

Ardjuna ( Ardjuna

2D Structural contour map of the Talang Akar Formation Akar Talang the mapof contour Structural 2D

37 Figure

Appendix II: 3D models and cross sections

Sunda and Asri Basins: 3D Structural models

Depth (feet)

Distance (meters)

Figure 38 3D Structural model of the top of the Talang Akar Formation- Sunda/Asri Basins

Depth (feet)

Distance (meters)

Figure 39 3D Structural model of the top of the Air Benakat Formation- Sunda/Asri Basins

Sunda and Asri Basins: Cross Sections

Figure 39 is the location map of Sunda/Asri Basins displaying the section line for cross section 3

Figure 40 Location map for cross-section A-A'- Sunda/Asri Basins, Distances in meters

Cross section -G G’ G G’

Figure 41 Cross-section 3 G-G’, SW-NE displaying the structural trends in Talang Akar Formation (TAF), Air Benakat Formation (ABF) and the basement.

Ardjuna (NW Java) Basin: 3D structural models

Depth (feet)

Distance (meters)

Figure 42 3D Structural model of the top of the Talang Akar Formation- Ardjuna Basin

Depth (feet)

Distance (meters)

Figure 43 3D Structural model of the top of the Air Benakat Formation- Ardjuna Basin

Ardjuna (NW Java) Basin: Cross sections

H’

Figure 44 Location map for cross section H-H’, Ardjuna Basin, Distances in meters

Cross section -H H’

H H’

Figure 45 Cross section H-H’, N-S displaying the structural trends in Talang Akar Formation (TAF), Air Benakat Formation (ABF) and the basement.

Appendix III: Tables

Tables 2, 3 and 4 show the measured distances between the producing wells and the grabens, for the

South Sumatra, Sunda/Asri and Ardjuna Basins respectively.

Table 2 Distance measurement table for the South Sumatra Basin

Distance in km Rimbabat 2 32.066 Bulian 18.498 Bentajan 10 20.413 Bentajan 8 25.042 Bentajan 9 28.336 Bentajan 11 26.682 North Kluang 41 1.88 Jemakur 6.637 Kerang 1 12.875 Kerang 2 12.728 Kerang 3 13.085 Tabuan 1 21.663 Tabuan Selatan 18.190 Average 18.315

Table 3 Distance measurement table for the Sunda and Asri Basins

Distance in km Lestari 1 12.611 Nurbani 3 10.783 PSI ZUD 8.088 Average 10.494

Table 4 Distance measurement table for the Ardjuna (NW Java) Basin

Distance in km PSI FT1 8.169 PSI FT4 6.336 PSI OV 9.184 PSI OY 3.772 PSI XW 2.000 PSI XW3 2.620 PSI X3 9.235 PSI GG3 11.733 PSI WG 14.321 PSI P6 20.656 PSI P11 18.228 PSI P2 20.613 PSI P10 19.331 PSI ML 5.216 PSI MV 0.447 Average 10.124

Table 5 Well log data

Bore Longitude Latitude Elevation Total Depth Abab 104.15694 -3.21667 46 5862 Asri 1 106.88333 -4.73333 56 10377 Astari 106.83737 -4.40866 -70 3019 Bakung 108.88906 -6.37009 69 4115 Bakung(stanvac) 104.19750 -2.16972 -3 3875 Banuwati 2 106.43291 -5.04110 -72 9787 Bentajan 10 104.08028 -2.37139 68 4198 Bentajan 11 104.13250 -2.40833 30 4230 Bentajan 12 104.09056 -2.40222 14 4370 Bentajan 8 104.12069 -2.40014 51 5498 Bentajan 9 104.13583 -2.40833 67 4549 Bentu 2 101.56566 -0.36438 11 4600 Berlian 1 106.67953 -4.45599 -71 3235 Besai 1 104.68798 -4.53368 278.2 4069.55 Betara 103.41028 -1.13056 65.6 5065.6 Budiarti 1 106.14750 -5.35194 -101 4069 Budiarti 2 106.14801 -5.28423 -72 6051 Buka 103.41042 -3.45599 292 3867

Bulian 104.06639 -2.32139 86 4492 Bunga 104.17038 -2.75405 21 3178 Candi(Tjandi)1 104.05194 -3.33306 151 7847 Capang 105.12930 -4.76131 100.4 1875 cecilia 1 106.33431 -5.06072 -85 8331 cicih 106.35159 -4.75007 -83 6861 Cikarang 107.19322 -6.19252 55.77 8717 Cilamaya Timur 107.56657 -6.20976 6 8258 Cimalaya Utara 2 107.50939 -6.22392 10 7994 Cinta 106.2578 -5.46236 -125 3530 Ciwaringin 107.32912 -6.39173 156 8080.7 Cory 106.40111 -4.84444 -63 6877 Darmi 1 106.18335 -4.76803 -68 3912 Dedeh 1 106.48958 -4.75994 82 4500 Dempo 1 108.35266 -5.53079 82 4500 Dewi selatan 1 106.71972 -4.58083 -63 5977 Djambu 1-28 102.20639 -1.33778 207 3389.108 Elly 1 106.11091 -5.42401 -81 3979 Emi 1e 106.44772 -5.38778 117 5497 Enny 1 106.26847 -4.48431 54 4098 Erna 1 106.77222 -4.95194 -72 3463 Esi 106.73473 -4.62814 -71 7153 Fanny 106.41070 -5.21812 -74 11213 Farah 3 106.24150 -5.09991 -90 5530 Farah 5 106.26213 -5.10946 -87 6577 Flora 106.63851 -4.51769 -70 3216 Gaby 1 106.74524 -4.65217 -80 7761 Gajah 1 106.80778 -2.48556 172 5243 Gayatri 1 106.30139 -4.55333 34 4311 Gede 106.11514 -5.16817 -72 4780 Gita 6 106.37922 -5.37000 -116 6217 Gita A-7ST2 106.37906 -5.36972 -114 7874 GN1 107.26784 -5.36129 79 3481 Grissik 37 103.96222 -2.30861 56 6393 Hariet 1 106.79158 -4.66655 -72 10133 Harimau 1 104.18931 -3.59247 146 7754 Harimau 2 104.19980 -3.58907 99 7611 Harimau 3 104.19966 -3.59953 115 7655 Harimau 3A 104.19944 -3.59972 115 7643 Harimau 4 104.20572 -3.59440 123 7815 Harimau 6 104.20502 -3.59043 119 7621 Harimau 7 104.21046 -3.58073 81 7409

Harimau 9 104.21747 -3.55180 89 6226 Hatty 1 106.20944 -5.63111 -173 4099 Hera 1 106.53222 -4.82278 54 6578 Herawati 1 106.46422 -4.80966 -74 5613 Ibul 1 103.94372 -3.22833 108.14 5703 Ibul 2A 103.95265 -3.21768 145 6232 Ida 1 106.60472 -4.89167 -65 5517 Ina 1 108.91192 -5.44367 -163 2635 Indah 106.24964 -5.19639 -86 3814 Intan 106.65496 -4.58061 0 3699 Ira 106.69244 -4.53646 -71 3874 Irma 106.96750 -4.65903 -65 4310 Jambu 104.34408 -3.28472 25 5005 Jangga 103.22844 -1.96286 126 2353 Janti2 103.40250 -4.92972 -33 2558 Jemakur 104.09666 -2.74376 40 5095 Judy 106.22417 -5.61639 -162 5232 Kapas Strat 1 103.31509 -2.23609 202 2500 Karlina 106.22828 -5.44481 -121 4370 Kartika 106.72304 -4.91857 -70 7504 Kartini 1 106.48694 -5.10833 -69 11927 Kartini 2 106.48503 -5.08994 67 6497 Kartini 3 106.48960 -5.12065 -74 6634 Kartini 4 106.48444 -5.10028 -70 6389 Kartini 5 106.49262 -5.10153 -70 6440 Kartini Utara 106.49006 -5.07514 -70 6500 Katomas 107.77151 -6.43745 134 8395.7 Kejumat 102.52028 -2.23319 232 4435 Kemala 106.53783 -4.93254 -74 5719 Kerang 1 104.15206 -2.72894 8 3551 Kerang 2 104.15374 -2.72518 47 3500 Kerang 3 104.15719 -2.72737 49 3435 Ketaling 1 102.50778 -1.76667 47.5 5249 Kijang 104.18279 -3.62082 147 7853 Kitty 106.19986 -5.51583 59 2912 KMM1 107.42022 -6.03828 -12 9269 Krisna 1 106.16667 -5.19250 -79 4187 Krisna 12 106.21611 -2.16500 -82 5217 KRK 2 107.42154 -6.25681 32 7911 Kukui 103.53472 -2.62167 94 6307 Laksmi 1 106.19351 -4.86978 -75 4479 Lastri 106.40621 -5.27046 -75 8889 Lematang 104.26694 -3.20833 25 5973

Lematang south 104.27875 -3.23219 30 5987 LES1 107.55020 -5.96962 -82 3810 Lestari 1 106.18269 -5.66942 -215 2314 Lestari 3 106.16922 -5.68974 -198 3182 Linggau 102.95065 -3.09448 161 8672 Lisa 1 106.52631 -4.90650 -70 5894 Lita 1 106.21742 -5.48567 -120 5432 Lita 2 106.21727 -5.48568 -120 4743 Loyak 104.13139 -3.22250 47 6247 Lupak 103.92667 -0.97306 -7 4715 Mambang sebasa 103.24803 -3.02486 106 5926 Marwati 106.27523 -5.01024 -99 6406 Maya 106.26361 -5.19194 111 7017 MB 4/ RDH 2 107.30275 -5.97212 5 4962 Mela 3 106.15062 -5.28716 -70 4530 Melati 104.14457 -3.97863 262 5462 Mendarai 103.91451 -3.21321 69 5887 Menggala selatan 1 105.21025 -4.52984 44.65 2818.24 Menggala selatan 6 105.21025 -4.52984 45 2818.24 Merabu 3 104.97253 -3.91278 488 6665 Meruap 6 102.76635 -2.29011 223 3638 Mila 1 106.45222 -5.13111 56 11176 Mila 2 106.45591 -5.10686 -72 10346 Muria 107.94856 -5.60972 82 4218 Murni 106.14806 -5.61278 32 3357 Namai 103.21906 -2.24322 198 3984 Nani 106.45463 -5.24123 -74 10825 Nau 1 103.51333 -3.45639 296 5469 Nora 1 106.31472 -5.50222 56 4884 Nora 2 106.32167 -5.50667 58 3412 Nora A2 106.31528 -5.50194 67 3530 Nora South 1 106.31722 -5.53694 -120 3743 Nora South 2 106.31489 -5.51433 -114 3253 North Kluang 41 103.88778 -2.63611 130.56 3071 Notal 103.76945 -3.09955 132 5915 Nurbani 3 106.07565 -5.15676 -66 2177 Onny 106.45083 -5.48556 -83 2404 Padang Belawan 103.98670 -1.75874 96 5084 Pandan 104.19845 -3.34818 39 8115 Pasircatang 108.13117 -6.57627 125 7421 Peninjauan 102.68988 -1.66794 255 4019 Petar 104.28095 -3.15772 10 4731 Pilangsari 108.23383 -6.62264 86 7131

Prabumenang 5 108.23383 -6.62264 247 5399 PSI AA1 106.55306 -5.22333 -70 4309 PSI AA3 106.54333 -5.17389 -63 5150 PSI AA5 106.55056 -5.20889 -68 4562 PSI AA6 106.54758 -5.24606 -70 4352 PSI AA7 106.53471 -5.25714 -70 7069 PSI AAA1 106.70667 -5.20722 54 5697 PSI AB 1ST 106.52773 -5.29698 -79 7183 PSI AR1 106.53833 -5.14267 -70 6319 PSI AT1 106.50325 -5.07451 -69 8517 PSI AU1 106.52855 -5.11952 -70 7180 PSI AU2 106.51639 -5.11272 -68 7320 PSI DN1 108.05569 -5.71645 70 4605 PSI E15 107.99577 -6.04430 -117 6680 PSI ESP1 107.94799 -6.08048 40 7710 PSI EST1 107.94817 -6.06228 -104 6370 PSI EW1 107.82854 -5.91457 -139 5859 PSI EWZ1 107.87223 -5.86786 -143 6232 PSI FQ1 108.03351 -6.21024 -51 6936 PSI FQW 1ST 107.97934 -6.21346 73 10300 PSI FR1 108.20058 -6.08146 40 5110 PSI FSW1 108.05804 -6.24061 -44 7714 PSI FSW2 108.05355 -6.25976 -35 7946 PSI FSZ1 108.07935 -6.24402 -123 6975 PSI FT1 108.14306 -5.89069 -149 4489 PSI FT4 108.14917 -5.92356 -145 4696 PSI FTE1 108.21756 -5.91468 -146 4023 PSI FTX1 108.19950 -5.91060 -147 3705 PSI FV1 108.16250 -6.20194 40 7764 PSI FWN1 108.17728 -5.77010 -158 3927 PSI FX1 108.25108 -6.12914 65 5415 PSI G2 107.25898 -5.49061 -150 3297 PSI G3 107.27866 -5.47362 -147 3291 PSI GG3 108.63556 -6.46222 54 4952 PSI GGG1 107.38308 -5.47428 64 4307 PSI GP1 107.40411 -5.59675 -152 6863 PSI GQE1 107.31926 -5.68466 67 4928 PSI GQS2 107.26330 -5.70803 75 4270 PSI HH1 107.85972 -6.16583 50 7530 PSI HH2 107.87269 -6.16722 54 7697 PSI K3 107.66619 -6.04203 65 6605 PSI KK2 107.54488 -6.10914 -35 8220 PSI LL1 107.40472 -5.77133 57 5673

PSI LLQ 107.42392 -5.77206 40 6581 PSI LLX 107.49961 -5.77011 -137 9334 PSI MKN 107.35075 -5.92222 75 7725 PSI ML 107.18242 -5.94222 -32 4632 PSI MO 107.09279 -5.85525 -94 4327 PSI MP 107.03658 -5.83467 61 3264 PSI MV 107.23118 -5.88694 58 3970 PSI NF 106.54874 -5.01497 -73 6106 PSI NG 106.56734 -5.02721 -68 5700 PSI OE10 108.56868 -6.43633 71 6509 PSI OE8 108.54714 -6.45049 -17 7288 PSI OM 108.53549 -6.30755 -70 5228 PSI ON 108.48374 -6.28740 -67 5208 PSI OU 1 108.43292 -6.21294 -143 5067 PSI OU 3 108.42435 -6.20846 -104 5300 PSI OV 108.45643 -6.11417 -133 4076 PSI OWA 108.39725 -6.24956 -50 6500 PSI OX1 108.42708 -6.25403 -75 4939 PSI OX2 108.43536 -6.22917 -95 4566 PSI OY 108.44500 -6.16958 -121 4310 PSI OZ 108.35878 -6.16169 -111 5040 PSI P10 107.02222 -5.83064 -102 3290 PSI P11 107.05764 -5.78773 67 3483 PSI P2 107.01508 -5.81917 34 3452 PSI P6 107.04126 -5.76667 65 3585 PSI P7 107.02897 -5.79081 -106 3361 PSI P9 107.04278 -5.80736 -110 3414 PSI PM 107.03936 -5.63678 40 3756 PSI PN 107.10708 -5.50297 -151 3448 PSI PZ 106.85606 -5.51027 -137 3005 PSI SB 107.60385 -5.81017 -144 8472 PSI SC 107.58641 -5.73313 78 9982 PSI SD 107.63481 -5.70311 78 10097 PSI TY 107.45469 -5.62772 -156 7373 PSI U5 107.88145 -6.05996 65 7616 PSI UQ 107.92142 -6.12264 40 7637 PSI W 107.69472 -5.40444 87 3176 PSI WG 108.63931 -6.55593 84 5473 PSI X3 108.66694 -6.31722 -152 4541 PSI XM 1 108.56227 -6.28601 -89 5195 PSI XM3 108.57594 -6.29521 71 5276 PSI XW 108.59977 -6.33668 -66 4100 PSI XW 3 108.60733 -6.33384 -72 4050

PSI Z 106.67778 -5.36528 54 4266 PSI ZUD 106.55944 -5.35656 -95 2953 PSI ZZZ 106.53644 -5.32156 63 3295 Putih 103.99244 -3.98867 33 6762 Quinta 106.66500 -4.91639 60 6347 Rama 106.28894 -5.44736 -123 4022 Riamar 106.40671 -4.70944 0 7245 Rima 109.14111 -5.29361 32 3269 Rimbabat 2 104.13146 -2.13146 10 3262 Rimbo 104.33773 -2.93423 68 1972 Rini 106.27030 -5.50023 -114 8917 Rinjani 108.40158 -5.60849 60 3627 Rumbi 104.13080 -2.76473 30 2918 Sambidoyong 108.38254 -6.37154 5 9808 Saung naga 103.18242 -3.61471 269 3701 Selangit 1 103.01869 -3.78901 144 6046 Selatan 2 106.18583 -5.55500 120 3277 Semeru 108.38819 -6.01746 82 3958 Semi 102.99389 -3.38000 275 2942 Serian 102.51667 -1.47917 151 4111 Siarak 103.72861 -2.74250 73 8495 Sibayak 108.23945 -5.84501 60 4279 Sita 106.42431 -4.99908 -77 10587 Soputan 108.46515 -5.64190 82 5260 Sri 106.03450 -5.16872 47 2692 Sukaraja 1 104.03720 -3.19703 18 7345 Sukaraja 2 104.03068 -3.19083 15 6856 Sukaraja 3 104.03442 -3.19322 13 6798 Sukaraja 7 104.01965 -3.18131 17 6960 Susana 106.66536 -4.59440 -70 4059 Tabuan 1 104.21778 -2.71417 10 4067 Tabuan Selatan 104.21650 -2.74695 6 2230 Talang Gendum 103.94734 -3.28864 162 6760 Talau 102.25496 -0.18026 36 6299 Tambun 107.02883 -6.13331 13 2340 Tampan 104.22772 -3.12444 20 4648 Tanjung kurung 1 104.12435 -3.12231 16 5527 Tapir 103.81698 -3.51109 117 6363 Tasim 104.05922 -3.81941 216.5 6425 Tebing Tinggi 103.09806 -1.01389 79 5361 Tiara 106.19331 -5.07736 -63 4599 Tiga Duri 104.18222 -2.47889 7 4732 Widuri 1 106.62632 -4.66436 -70 3750

Yasrid 1 106.91816 -4.81944 -78 10263 Yati 1A 106.14278 -5.47861 -99 4332 Zelda 1 106.37361 -3.18750 -70 8342 Zelda 4 106.35536 -5.05900 -72 8182 Zelda 7 106.37722 -5.12000 -77 8954

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