Oil Shale Prospect in the

Buton Island, Southeast Sulawesi,

INDONESIA

Hadiyanto, S.M. Tobing, and Hendro Fujiono

CENTER FOR GEO-RESOURCESGEOLOGICAL AGENCY

MINISTRY OF ENERGY AND MINERAL RESOURCES REPUBLIC OF INDONESIA

CGR

LOCATION

OIL SHALE STUDY

� Deskwork study based on previous investigations by the Center of Geo-Resources (CGR).

� This study used outcrop data of oil shale/ Buton’s asphalt/tar sand and drilling activities results. Geochemical analysis was also done for this study.

� The goal was to estimate hypothetical oil shale resources on Buton Island.

� Three study area in the Buton Island: Pasarwajo, Lawele and Sampolawa blocks.

� Pasarwajo and the vicinity is about 48 kms from Bau-Bau (capital city of the Buton Regency), that lies on the coordinates: Longitude 122° 45′– 123° 00′ E and Latitude 5° 15′– 5° 30′ S and of Map sheet No. 2210 – 62 scale 1 : 50,000 (Fig.1) on Topographic Map of Indonesia (Bokosurtanal, Edition I –1992).

� Lawele block is administratively included in the Kapontori and Lasalimu Districts, Buton Regency. Geographically included in Map Sheet No. 2210-64 published by Bakosurtanal, with coordinates 122o45’00’’ - 123o00’00’’ E. Long. and 05o00’00’’ - 05o15’00’’ S. Lat.

� Sampolawa is administratively included in the Sampolawa District, Buton Regency, geographically include in Map Sheet No. 2210-33 (Mambulu sheet) published by Bakosurtanal in scale 1 : 50,000, with coordinates: 122o30’00’’ - 122o 45’00’’ E. Long. and 05o30’00’’ - 05o45’00’’ S. Lat.

3

Sampolawa (2003; 2004)

Lawele (2002)

CGR

Study Area

Pasarwajo

�� Buton Island is an Buton Island is an extension extension ofTukangbesiofTukangbesi–– Buton, according to Buton, according to geologists it frequently geologists it frequently in contact with in contact with MandalaMandalaof East Sulawesi.of East Sulawesi.

�� Composed of Mesozoic Composed of Mesozoic Rocks (Triassic Rocks (Triassic –– Upper Upper Crustaceous Crustaceous ––Paleocene), and Cenozoic Paleocene), and Cenozoic Rocks (Rocks (TertieryTertiery ––QuarteryQuartery) )

�� Repeated Repeated tectonismtectonismdeformed the older deformed the older rocks resulting in rocks resulting in relatively steep dips. relatively steep dips.

REGIONAL GEOLOGY REGIONAL GEOLOGY

CGR

Ereke

Sampolawa

Kalisusu

Lawele

Kabungka

REGIONAL GEOLOGY

I.Mesozoic Rocks (Tertiary – Upper Crustaceous– Paleocene) consist of: Winto, Ogena, Rumuand Tobelo Formations

II. Cenozoic Rocks (Early Miocene – Plistocene) consist of:Tondo, Sampolakosa, and WafulakaFormations.These rocks covered most of the Buton Island.

CGR.

Regional Stratigraphy

?

M E

S O

Z O

I K

U M

Batupasir, Konglomerat

P A L E O Z O I K U M

Serpih, Napal

J U R A

T R I A S

OGENA

195

225

M E T A M O R P H I K(S C H I S T, P H Y L L I T E)

Karbonat

?

No data

D I A S T R O P I S M E

No data

T U F AP L I O S E N

K A P U R

?

R U M U

130

P A L E O S E N

M I O S E N

O L I G O S E N

E O S E N

T E

R S

I E

R

K E

N O

Z O

I K

U M

W A N I ?

T O N D O

5.5

22.5

36

T O B E L O

55

65

F O L D I N G

?

MEFA

SASIFU?

KARTINA

?

GREYWACKE

M I T I N G

F O L D I N G

DIASTROPISME

F O L D I N G

PERIODEZ A M A N

H O L O S E NPLEISTOSEN

B U T O N

a l u v i a l

r e e f

STH

106

SAMPOLAKOSA

WCNB U R U

a l u v i a l

r e e f

ES E R A M

a l u v i a l

r e e f

W I N T O

Stratigrafi Regional Daerah Buton

• Winto Formation (Late Tertiary ), consisting of intercalation of shale, limestone, calcarenite and calcareous sandstone; neritic-deep sea environment.

• Tondo Formation (Early Miocene), consisting of intercalation of conglomerate, sandstone, silt, and reef sandstone in the lower part.

• Sampolakosa Formation (early Pliocene), consisting of napal and calcareous sandstone with insertion of cacarenite thin layer

CGR

Courtesy: Muh. D. Guntur

1

2

3

CGR

BELT OF BUTON’S TAR SAND/ASPHALT

Pasarwajo Block� Rocks formation containing oil shale and or

asphalt/tar sand particularly occurred in the Tondo and the Sampolakosa Formation.

� On the Tondo Formation, asphalt/tar sand and oil shale deposits occurred on the layers of sandstone and calcareous sandstone or napal.

� On the Sampolakosa Formation, the content of asphalt/tar sand and oil shale were accumulated in the shape of lenses on the calcareous sandstone and napal.

� From some outcrops, thickness of layers containing asphalt/tar sand/oil shale on the Tondo or Sampolakosa Formation varied from 0.10 m and >5.0 m with its distribution.

� Rock layers containing oil shale are present in the Winto and Ogena Formations.

� Oil shale in both formations occurred as grey, blackish grey and black shale layers varying between 0.10 m and 15.0 m thick.

� In between shale layers occur thin laminations of sandstone and limestone with thickness of 1 – 10 cm commonly containing plant remnants of brown-black colour, attached to upper or lower part of shale layers.

� The rock outcrops occurred at Kumele Winto, KumeleKowiana, Batuawu and Mompenga Rivers. Seepage oil is also found on the fault contact between Winto and Sampolakosa Formation in the Winto River.

Pasarwajo Resources

� Two groups of oil shale resources: oil shale resources in calcareous sandstone of the SampolakosaFormation of Tertiary Age and oil shale resources on blackish grey –grey shale of the Winto Formation and Ogena Formation.

Sampolakosa Formation

� Based on the asphalt/tar sand exploitation area owned by State Enterprise/PT. SaranaKarya, the distribution of sandstone samples analyzed was about 2.5 km².

� If the thickness of each outcrop was between 2 – 6 m and the specific gravity of 2.78 kg/tons, the resources of this area were: 2,500,000 x 4.0 x 2.78 kg/ton = 27,800,000 ton of asphalt/tar sand.

Winto and Ogena Formation

� The tonnage estimation is based on the distribution in the lateral direction obtained from the correlation of several outcrops; there were six (6) oil shale layers. Volumes in these six layers could be estimated based on calculations.

� One layer was correlated between outcrops separated by 1,000 m.

� The layers were delineated up to a depth of 100 m vertically from the line of the outcrop surface, thus the width of outcrops was:

W = 100/sin α, where α is dip angle of oil shale layer

� Layer thickness is the average thickness of entire oil shale included in that layer.

� Oil shale resources can be calculated with the formula:

Resources = { [Length (m) x Width (m) x Thickness (m)] x Specific Gravity (gr/ton)}

12,791,858.9

3,845,060.02.635.00146.2200020eALB-04

AKB-35

AKB-

34A473,264.12.701.1576.21200041d

AKB-34

406,011.61.741.5077.78200040cAKB-39

477,523.22.042.2053.2200070bAKB-40

7,590,000.02.5315.0100200030aAKB-42

Resources

(ton)

Specific

Gravity

Thickness

(m)

Width

(m)

Length

(m)DipLayer

No

Outcrop

Lawele Block

� Data of Lawele block indicated that oil shale deposits are present within the sandstone layer of the Tondo Formation and in the sandy limestone of Sampolakosa Formation.

� Prospective yield occurred south of Suandala, Lawele, and Kamaru villages. Oil shale of the Lawele block generally is asphalt/tar sand in porous calcareous sandstone on the Sampolakosa and Tondo Formations.

� Megascopically, rocks contain oil shale in this area is calcareous sandstone and calcareous limestone filled by asphalt/tar sand seepage.

� Retorting analyses of selected samples indicated that rocks containing oil shale deposits that came from the Tondo and Sampolakosa Formations, showed oil content of both Formations ranged between 30 – 90 l/tonne.

� Petrographic data shows that this block generally contains fine clastic rocks consisting of carbonate and impregnated with asphalt/tar sand.

� The mean maturity level of rocks was Rv = 0.46%. Organic material was dominated by lamalginite and neither liptinite nor vitrinite were present. Lamalginite was present as very thin and fine filmy sheets. Lamalginite presents medium fluorescence intensity, yellowish pink in colour.

� According to the assessment, the distribution of rock layer in the Lawele Block indicates a distribution from Southwest to the Northeast.

� From previous drilling data, thickness of sandstone layer bearing asphalt/tar sand seepage varied from 2.50 m – 10.30 m. On the lower part of the sandstone layer was intercalated sandstone and claystone. The thickness of the sandstone intercalation bearing asphalt/tar sand seepage on the lower partwith the claystone varied from 0.20 m – 0.50 m.

� The previous information indicated that asphalt/tar sand are deposited only along the east coast of the Lawele Bay and are believed to be the lateral equivalent of asphalt/tar sand deposits at Sampolawa area (Rongi village) and Pasarwajo(Kabungka village).

� The distribution of the oil shale based on the study indicates that sandstone layers containing asphalt/tar sand seepage as a sandstone layer well splitted to the Southeast or Northeast having thickness of >6,00 m - 10,30 m.

� However, toward the Northeast the asphalt/tar sand sandstone layer thinned into 2,50 - 3,00 m, and it was similar to the asphalt/tar sand sandstone layer on the southeast part of the Lawele River which is 1.00 m thick.

� Asphalt/tar sand sandstone layer thickness of the lower part was about 0.20 m – 0.50 m, and in the upper part about 2.50 m – 10.30 m.

� Estimation of oil shale resources (asphalt/tar sand) was delineated for oil shale layers with minimum thickness of 1.00 m.

� Lateral distribution of each layer that could be correlated was delineated up to 500 m from the last outcrop or stopped at the fault structure.

� Layer thickness is average thickness from oil shale layer from drilling data or outcrop measurement included in one calculation block.

� Based on the calculation result, oil shale resources up to 100 m depth in the Lawele Block and vicinity was 60.991.554,38 tons asphalt/tar sand.

� Formula to calculate OIL Resources

Oil resources = [{Oil shale resource x Oil content (average l/ton)} : 159]

No Block Length

(m)

Width

(m)

Thickness

(m)

Specific

Gravity

(kg/ton)

Resources

(Ton)

1 A 1000 274,75 2,50 2,25 1.545.468,75

2 B 1100 373,20 8,50 2,25 7.851.195,00

3 C 1100 274,75 10,00 2,25 6.800.062,50

4 D 1300 274,75 7,50 2,25 6.027.328,125

5 E 1000 250,00 2,50 2,25 1.406.250,00

6 F 1100 450,00 8,50 2,25 9.466.875,00

7 G 1100 750,00 10,30 2,25 19.119.375,00

8 H 1300 400,00 7,50 2,25 8.775.000,00

Total 60.991.554,38

No. Block

Rock

resources

(Ton)

Oil content

(l/ton)

Oil resources

(Barrel)

1 A 1,545,468.75 60.0 583,195.75

2 B 7,851,195.00 67.5 3,333,054.48

3 C 6,800,062.50 63.0 2,694,364.39

4 D 6,027,328.13 35.0 1,326,770.34

5 E 1,406,250.00 60.0 530,660.38

6 F 9,466,875.00 90.0 5,358,608.49

7 G 19,119,375.00 60.0 7,214,858.49

8 H 8,775,000.00 60.0 3,311,320.75

Total 60,991,554.38 24,352,833.07

Sampolawa Block

� Oil shale deposit layers at Sampolawa Block occurred in the Winto Formation. There are at least twenty-four layers at the 26 m depth with thickness starting from 0.10 – 1.20 m. Total thickness of the entire oil shale/shale layers was 10.34 m.

� There were three main oil shale layers with the thickness of >0.50 m - 1.12 m, 1,20 m and 1.05 m There were also six oil shale layers with thickness of ~0.50 m. The rest (15 layers) relatively thinner less than 0.50 m.

� Oil shale layer in the Winto Formation are intercalated between silt/calcareous sandstone, soild, hard – very hard and shale (as oil shale layer). Lateral distribution follows theformation from Southwest – Northeast.

� Oil shale layers are cut by fault structures that occur in the Sampolawa Block. However, the continuity of layers can still be traced across the fault.

� In addition to oil shale in layers, oil shale deposits in form of asphalt were also found in the Sampolakosa Formation at the Rongi area (about 12 km northeast of the study area). The calcareous sandstone layer thickness reaches more than 10 m with its distribution aligned almost North – South.

� Oil liquid/asphalt/tar sand of the oil shale deposit occurred inlayers of calcareous limestone resulting in black rocks, which soil the hand on contact. When a rock sample is burnt, it has avery strong asphalt/tar sand odour.

� Petrographic analysis shows that all analyzed layers contain lamalginitearound 0.5 – 50%. Other organics that found were kutinite, sporinite, and liptodetrinite of 0.1 – 2%, while dispersed organic matter consisted of vitrinite macerals, liptinite, internite that varied from 0.5 –50%. Fossil fragments were rare to absent, whereas iron oxide and pyrite content ranged from 0.5 – 50%.

� Oil shale deposit layers in Winto Formation can be categorized as oil shale or lamosite of Rundel type influenced by marine sedimentary environment.

� The Winto Formation could be categorized as immature as shown bymean value of vitrinite reflectance Ry ranging from 0.20% – 0.61%. The values suggest a lower thermal gradient.

� Petrographic analysis of the Winto Formation outcrop in the Buton Island indicates similarity to oil shale of other study areas.

� The study area is divided into three blocks of resources estimation based on the fault structures presence in that area

No.

Block Layer

Thick

(m)

Oil content

(L/Ton)

Rocks

Resources

(Ton)

Oil

resources

(L/Ton)

1 1.05 10 286,177.50 2,861,775

2 1.20 20 345,000.00 6,900,000

3 1.12 20 325,864.00 6,517,280 Block I

4 1.48 20 486,772.00 9,735,440

Total 1,443,813.50 26,014,495

1 1.05 10 273,735.00 2,737,350

2 1.20 20 345,000.00 6,900,000

3 1.12 20 325,864.00 6,517,280 Block II

4 1.20 20 409,860.00 8,197,200

Total 1,354,459.00 24,351,830

1 1.05 10 457,884.00 4,578,840

2 1.20 20 552,000.00 11,040,000

3 1.12 20 521,382.40 10,427,648

Block

III

4 1.20 20 303,600.00 6,072,000

Total 1,834,866.40 32,118.488

TOTAL 4,633,138.90 82,484.813

CONCLUSIONSCONCLUSIONS

–– Asphalt/tar sand resources in the Asphalt/tar sand resources in the PasarwajoPasarwajo

Block was 27.8 million tons; oil shale/shale: Block was 27.8 million tons; oil shale/shale:

12.8 million tons. 12.8 million tons.

–– Asphalt/tar sand resources in the Asphalt/tar sand resources in the LaweleLawele Block Block

was 60.99 million tonswas 60.99 million tons ; oil resources were ; oil resources were

24.35 million barrels.24.35 million barrels.

–– Oil shale/shale resources in the Oil shale/shale resources in the SampolawaSampolawa

Block was 4.63 million tons; oil resources were Block was 4.63 million tons; oil resources were

518,772 barrels.518,772 barrels.

CGR

� Oil shale deposit prospect occurring in the study area have not yet be defined as to economic level.

� The utilization of oil shale faces some constraints related to the separation process between asphalt rocks and asphalt/tar sand oil/hydrocarbon that are relatively more difficult.

� Based on the study by the CGR, the oil shale/shale layers occurring in the Winto formation are quite abundant and their distribution is very vast. However, this conclusion is based on a very limited data.

� Deeper core drilling is recommended for further development.

Tar sand Outcrop of Tar sand Outcrop of SampolawaSampolawa AreaArea

Intercalation between Intercalation between oil shale layers and oil shale layers and calcareous silt of the calcareous silt of the Winto Formation.Winto Formation.

CGR

Tar sand Hill of Tar sand Hill of RongiRongi, , SampolawaSampolawa AreaArea

White color is White color is calcareous sandstone, calcareous sandstone, weathered, not weathered, not permeated by asphaltpermeated by asphalt

Dark color is asphalt Dark color is asphalt stone, in hill shape ; stone, in hill shape ; delineation of delineation of weathered rocks and weathered rocks and oil stained rocks is oil stained rocks is very clear. very clear.

CGR

TarsandTarsand/Asphalt Stone/Asphalt Stone

Boulders of tar Boulders of tar sand/asphalt from sand/asphalt from mining activity at the mining activity at the RongiRongi areaarea

Oil seepage / tar sand Oil seepage / tar sand / asphalt from/in / asphalt from/in calcareous silt of the calcareous silt of the Winto Formation Winto Formation

CGR

Outcrop of tar sand / asphalt open pit in the Rongi area. Boundary of weathered rocks and tar sand / asphalt is very clear. Asphalt / Tarsandthickness >> 10 m

Tar sand / liquid oil seeped in to calcareous sandstone (SampolakosaFormation)

CGR

Asphalt / tar sand / Asphalt / tar sand / liquid oil dripping from liquid oil dripping from calcareous sandstone calcareous sandstone Location is owned by Location is owned by private company at private company at RongiRongi, , SampolawaSampolawa..

Calcareous sandstone Calcareous sandstone permeaetedpermeaeted by oil/asphalt by oil/asphalt called asphalt stone/tar called asphalt stone/tar sandstone. White color is sandstone. White color is weathering calcareous weathering calcareous sandstone unstained by sandstone unstained by oil/asphalt. oil/asphalt.

CGR

Outcrop of Oil ShaleOutcrop of Oil Shale

Oil shale / Oil shale / Shale within Shale within calcareous silt (calcareous silt (WintoWintoFormation).Formation).

Outcrop of calcareous Outcrop of calcareous silt intercalated with silt intercalated with oil shale layer (oil shale layer (WintoWintoFormation) Formation)

CGR

Oil shale within CoreOil shale within Core

Core Sample; dark Core Sample; dark color is oil shale; color is oil shale; bright color calcareous bright color calcareous silt. Oilsilt. Oil staining visible staining visible in core. in core.

CGR

Outcrop of oil shale : Outcrop of oil shale : shaleshale--clay stone clay stone (Winto Formation) (Winto Formation)

Outcrop of oil shale and Outcrop of oil shale and seepage of oil / asphalt seepage of oil / asphalt on Winto Formation on Winto Formation

CGR

Oil shale layers in between calcareous silt (Winto Fm).

Outcrop of oil shale layer and seepage of oil (Winto Fm).

CGR

Oil shale insertion between two layers of calcareous silt (WintoFormation).

‘Stockpile’ of asphalt in Rongi (SampolakosaFormation).

CGR

Oil shale outcrop in Oil shale outcrop in KabungkaKabungka area area

Outcrop of shale containing oil/tar sand in KumeleKowiana (Winto Formation), Pasarwajo.

Outcrop of Calcareous Sandstone containing tar sand / oil (SampolakosaFormation) , Pasarwajo

CGR

Seepage of Oil / Seepage of Oil / TarsandTarsand in in KabungkaKabungka

Oil seepage in Kumele(Winto Formation), Pasarwajo.

Seepage of tar sand formed asphalt veins in soil surface (Sampolakosa Formation), Winning village, Pasarwajo.

CGR

Photomicrograph of Oil Shale

CGR

Lamalginite present as layers/ lamellae on claystone (Winto Fm) (ultraviolet light).

Lamalginite and bitumen in rock sample Sampolakosa Formation (ultraviolet light ).

Outcrop of Oil shale in Outcrop of Oil shale in LaweleLawele

Outcrop of calcareous Outcrop of calcareous sandstone containing sandstone containing asphalt seepage at asphalt seepage at LagunturuLagunturu village village

Intercalation of Calcareous Intercalation of Calcareous sandstone and claystone sandstone and claystone ((Tondo Fm), River Tondo Fm), River Suandala, Suandala village Suandala, Suandala village

CGR

Core sample at Di Core sample at Di LaweleLawele

Core sample containing Core sample containing Tar sand sandstone layer. Tar sand sandstone layer. ((TondoTondo Formation) Formation)

Calcareous sandstone Calcareous sandstone outcrop (outcrop (SampolakosaSampolakosaFormation) containing Formation) containing seepage from Tar sand in seepage from Tar sand in KamaruKamaru villagevillage

CGR

Outcrop of Oil Shale in Outcrop of Oil Shale in KalisusuKalisusu ((MunaMuna Regency) Regency)

Seepage from oil / Seepage from oil / asphalt / tar sand in asphalt / tar sand in TondoTondo Fm. In Fm. In ErekaErekaarea. area.

CGR

Oil shale layer (Winto Formation) in Labuan (MunaRegency)

Seepage of oil / asphalt in Seepage of oil / asphalt in River River SiloiSiloi, , RaimunahRaimunahMaliganoMaligano village on village on calcareous sandstone calcareous sandstone TondoTondo Fm. Fm.

CGR

� Photomicrograph of Oil Shale in SampolakosaFormation (Fluorescence image)

CGR

Courtesy: Herudiyanto

Calcareous sandstone outcrop containing seepage of asphalt from SampolakosaFormation, LaweleVillage

Calcareous sandstone outcrop containing seepage of asphalt from SampolakosaFormation Suandalavillage

CGR