IPA 87-1 1 /06
PROCEEDINGS mDONESIAN PETROLEUM ASSOCIATION Sixteenth Annual Convention, October 1987
AN OVERVIEW OF SOURCE ROCKS AND OILS IN INDONESIA
Kevin M. Robinson *
ABSTRACT
Source rocks in the hydrocarbon productive basins in Indonesia can be classified as lacustrine, fluvio-deltaic and marine. Lacustrine source rocks are the most productive, and have sourced most of the oil in Central Sumatra, some of the oil in the Sunda Basin and also possibly oil in the West Natuna Basin. Fluvial-deltaic source rocks are the most common and widely dispersed and have sourced oil in the majority of foreland (back-arc) basins of Western Indonesia. Marine source rocks probably occur in Eastern Indonesia, but are poorly documented. However, they may have sourced oil in the Salawati Basin and eastern Sulawesi. Positively identified producing source rocks are all Tertiary in age, although PrsTertiary (Permian/Jurassic) rocks are suspected to source oil in the Bintuni and Bula (Seram) Basins and are also a possible source in eastern Sulawesi and the Banggai-Sula area east of Sulawesi.
Crude oils in Indonesia can also I be characterized as lacustrine, fluvio-deltaic and marine based on a range of geochemical parameters, including pyrolysis-gas chromato- graphy on the oils asphaltene fraction and GC-MS biomarker data. Lacustrine oils sourced from non-marine algae are generally low-medium gravity, waxy, low sulfur oils and often contain'unusually high concentrations of C3O 4-methyl steranes. Marine oils derived from marine algae are low- medium gravity, low wax, medium-high sulfur oils and con- tain C27-C29 diasteranes and steranes in relatively high concentrations compared to other oil types. Fluvio-deltaic oils derived from higher plant, terrestrial organic matter are medium-high gravity, waxy, low sulfur oils. They contain abundant higher plant resin derived C30 alkanes and low concentrations of steranes which are dominated by C29 diasteranes and steranes.
INTRODUCTION Source rocks can be subdivided into different organic
facies type based on microscopic and geochemical techni- ques. The organic facies is dependent on the depositional environment of the rock. Similarly crude oils can be charact- erized into different genetic types, generally lacustrine, terrestrial and marine, based on detailed chemical composit- ion. The genetic category to which a crude oil belongs is -----_________ *) PT. CORELAB INDONESIA
obviously dependent on the original organic facies of it's source rock.
The main objectives of this paper are to
1) Categorise the source rocks of the major hydrocarbon producing basins of Indonesia into lacustrine (non-mar- ine algal), fluvio-deltaic (terrestrial) and marine (mar- ine algal).
2) Describe the general geochemical characteristics of the different source rock types.
3) Develop a scheme to classify Indonesian oils into lacust- rine, fluvio-deltaic and marine based on detailed geo- chemical analyses.
SCOPE
This paper attempts to cover all the major hydrocarbon producing basins of Indonesia (Fig. 1). Identification of source rocks within the basins is primarily based on previ- ously published data and on experience gained in the area. However, source rocks within some of the basins are unknown, postulated or unconfirmed by detailed oil/source rock correlation studies. The oil classification is based on detailed geochemical data on one .hundred selected oil samples covering all the major hydrocarbon producing basins of Indonesia (Fig. 1).
SOURCE ROCKS
The major source rocks or suspected source rocks of the hydrocarbon productive basins in Indonesia are given in Table 1 and discussed below by depositional environ- ment.
Lam strine Deep lacustrine productive source rocks containing non-
marine algae have only been positively identified in Cen- tral Sumatra (Pematang Brown Shale) and the Sunda Basin (Banuwati Shale) as shown in Table 1 .These lacustrine shales were deposited in Eocene to Oligocene, isolated, half graben, rift basins (Fig. 2). Lacustrine shales may also be the source of oil in the West Natuna Basin (Oligocene Barat Shale, Pollock et aL, 1 %4), although crude oil data suggests a different lacustrine depositional environment than that envisioned for the Pematang Brown Shale of Cen- tral Sumatra. Lacustrine shale source rocks may exist else-
© IPA, 2006 - 16th Annual Convention Proceedings, 1987
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where in Indonesia, particularly in the foreland (back-arc) basins of Western Indonesia, where rifting occurred in the Early Tertiary behind a volcanic island arc system.
The deep lacustrine shales of Central Sumatra were de- posited in subsiding basins, under tropical climatic condit- ions. The lake had no annual turnover, resulting in anoxic bottom waters, which favoured preservation of organic mat- ter rich in non-marine algae (Fig. 3; Williams e ta l , 1985). In shallow rift basins, where subsidence was only equal to the rate of deposition, humic rich lacustrine shales and coals wiU have formed instead (Central Sumatra Coal zone, Table 1).
Deep lacustrine shales are some of the most oils'product- ive source rocks in the world. In Central Sumatra they ac- count for over half of Indonesia's oil reserves (Woodside, 1984). Immature, lacustrine shales typically contain be- tween 1.0 to 10.0% total organic carbon and 50 to 100% oil prone, fluorescent non-marine algal derived amorphous kerogen. The pyrofysis yield (Sl+S2) is variable ranging from 4.0 to 75.0 mg hydrocarbons/gm rock, but is often very high. Hydrogen indicies are typically in the 400 to 900 range, with elemental kerogen hydrogen/carbon rat- ios usually greater than 1.4 (Table 2). Specific non mar- ine algae such as Botrycoccus braunii or the non-marine planktonic algae Pediastium spp can sometimes be ident- ified in the samples, while input from Botryococcus and dinoflagellates, can be inferred from GC-MS biomarker data (Wolf et aL, 1986; Brassel et al., 1986, Seifert and Moldowan, 1980).
Fluvio-Deltaic Source Rocks Fluvio-deltaic source rocks containing terrestrial de-
rived kerogen are the major source rocks of medium gravity, waxy crude oils in many of the foreland basins of Indo- nesia. In South Sumatra and N.W. Java (Sunda, Ardjuna, Jatibarang) Basin, Oligocene Talang Akar coals and shales have been identified as a major source of the oil, while in the Malacca Straits of Central Sumatra, Sihapas coals have generated some of the oil (Table 1).
In the East Java sea, Oligocene Kudjung I11 coals and shales and in the Barito Basin, Eocene Tanjung coals and shales are speculated to be the source of the oil (Tabb 1). Although neither of these correlations are proved in the published literature. In the offshore basins of East Kali- mantan, thick Middle Miocene and possibly younger delt- aic coals and shales are a proven source of the offshore Kutei Basin oils, while thick Middle Miocene to Pliocene deltaics are the likely source of Tarakan oils (Table 1).
The offshore deltaic sediments of the Kutei Basin are
well documented geochemically (Combaz and Matharel, 1978; Durand and Oudin, 1979; Hoffman etd., 1984; Oudin and Picard, 1982; Schoell et aL, 1983; Schoell et aL, 1985). The major source rocks belong to the Middle Miocene Balikpapan Group. It represents a phase of delta progradation which has continued, with transgressive interruptions, through to the present day (Oudin and Pi- card, 1982). The sediments were deposited by an eastward flowing river system into a subsiding basin with a north-south axis. A full suite of facies typical of deltaic sedimentation were deposited (Fig. 4). Organic carbon con- tent is relatively high throughout the deltaic sediments (often >2.%), but the best source rocks occur in the delta plain where coals tend to be concentrated (Fig. 5, Thompson, 1985).
Generation of hydrocarbons within the Kutei Basin is largely controlled by maturity, as thick, extensive, organic rich source rocks are present throughout a large part of the basin. The top of the oil window in the basin is variable, depending on temperature gradient, but in general is at about 2800 - 3000 meters (Schoell et aL, 1983). Oudin and Picard (1 982) have demonstrated that overpressure may also be important in the hydrocarbon distribution and type (oil or gas) within the Kutei Basin. In areas where the oil window is completely within the overpressure zone, generated oil cannot be expelled and is transformed to in situ gas. The Kutei Basin hydrocarbon generation model may also be applicable in the Tarakan basin, where sedi- mentation occurred along similar lines.
Fluvio-deltaic coal and shale source rocks have generated large volumes of oil in Indonesia and account for the major production of hydrocarbons in the Ardjuna and Kutei Basins. Fluvio-deltaic shale source rocks typically contain 2.0-10.0% total organic carbon with a pyrolysis yield of 6.0 to 20.0 mg hydrocarbons/gm rock. Coals usually con- tain 40.0 to 80.0% total organic carbon with very high py- rolysis yields of 150-300 mg hydrocarbons/gm rock (Ta- ble 2).
Fluvio-deltaic coals and shales generally contain only higher plant terrestrially derived organic matter, consisting predominantly of vitrinite with secondary amounts of cutinite and resinite. The total amount of waxy, oil prone, exinitic kerogen is usually in the 10-30%0 range. A small percentage of the vitrinite may also have &me liquid hy- drocarbon potential, based on its fluorescence under U.V.
light. This is probably due to impregnation of the vitrinite with, or inclusions of, submicroscopic exinite. This type of vitrinite, which is called desmocollinite (Stach, 1982), has a lower reflectance level than normal vitrinite. The shales and coals typically have pyrolysis hydrogen indic- ies in the 200-400 range and kerogen elemental hydro- gen/carbon ratios of 0.8 to 1 .O.
Liquid hydrocarbon extracts from fluvio-deltaic source
99
rocks usually have high pristane/phytane. ratios e3 .0) due to deposition in an oxik environment. They also have relat- ively high concentrations of waxy n-paraffins and C30 cyclic alkanes (identifiable by GC-MS) derived from higher plants.
Marine Source Rocks Marine algal rich source rocks are the major source of oil
in the world. But in Indonesia none have been positively identified in the literature. However, based on crude oil characterization a marine carbonate or calcareous shale source is suspected in the Salawati Basin of Irian Jaya (Phoa and Samuel, 1986; Hughes, 1984) and in eastern Sulawesi (Table 1). Deposition of the source rock would have occurred under anoxic conditions in a restricted marine basin. In Salawati a likely source is Early Miocene Klamo- gun carbonates and shales (Fig. 6), while in eastern Sula- wesi Early Miocene shales and carbonates are a possible source or alternatively Jurassic marine shales and carb- onates.
Immature, marine source rocks capable of generating oils in the Salawati Basin and Sulawesi area would typical- ly be expected to contain 0.5 to 5.0% TOC, moderate to high pyrolysis yields (2.0-30.0 mg hydrocarbons/gm rock) and an organic facies comprised mainly of oil prone, mar- ine, algal derived amorphous kerogen. Pyrolysis hydrogen indicies should be in the 300-600 range and kerogen ele- mental hydrogenlcarbon ratios > 1.2 (Table 2). Re-Tertiav Source Rocks
All the Indonesian source rocks positively identified and correlated to oil accumulations in the published liter- ature are Tertiaty in age. However, potential Pre-Tertiary source rocks have been identified in Eastern Indonesia (Chevallier and Bordenave, 1986) and are related to pre- break up of the Australian Plate in the Mid-Jurassic (Peck and Soulhol, 1986). In the Bintuni Basin of Irian Jaya two PrsTertiary sourced oil types possibly exist (Chev- allier and Bordenave, 1986) The major source of most of these oils is thought to be Late to Early Permian Aifat shales with Jurassic Tipuma shales or possibly Upper Permian Ainim coals acting as a source for the other oil type (Wiriagar oiI).All of the source rocks in theBintuni Basin are suspected to contain a predominantly terrestrial organic facies despite the marine setting of some of them.
In Seram (BuIa Basin) Early Jurassic-Late Triassic marine carbonates and shales are the suspected source of Pleisto- cene and Triassic reservoired oils (o’Sullivan et al., 1985). While marine potential Jurassic source rocks are also pre- sent in the Banggai-Sula area east of Sulawesi. OILS
The diagnostic characteristics of deep lacustrine, flu- vio-deltaic and marine sourced Indonesian oils are outlined in Table 3. The oils are characterized based on bulk analy-
ses such as API Gravity, Weight % Sulphur and Gas Chromat- ography, plus, more detailed analyses such as Carbon Iso- topes, Pyrolysis-GC on the oils asphaltene fraction and Gas Chromatography-Mass Spectrometry (GC-MS) biomarker analysis on the saturate fraction of the oils. The characterist- ics listed are for oils generated at normal thermal maturity levels (Ro 0.5 - 1.0%) and unaltered by processes such as thermal or biological degradation or water washing. Bulk Data
Bulk Data such as API gravity, weight percent sulfur, gasoline range analysis and whole oil/saturate fraction gas chromatography give useful indicators as to the source of an oil, but are not detailed enough to positively ident- ify its genetic origin.
Algal sourced oils, marine or non-marine, tend to have low-medium API gravities (20-35O) and pristanelphy- tane ratios less than 3.0. Initial differentiation of a non- marine algal oil from a marine algal oil can often be made based on sulphur content and wax content. Lacustrine oils are typically high wax (C31/C19 > 0.4), low sulphur (< 0.2 wt %); while marine oils are low wax ( < 0.4 C31/ C19), high sulphur ( > 0.2 wt %). Fluvio-deltaic sourced oils usually are medium-high API gravity (30-50’); low sulphur high wax crude oils (Table 3). They characterically have high pristanelphytane ratios 0 3.0) due to deposition of the source rock in an oxic environment (Powell and McKirdy, 1975).
The n-alkane distribution of oils (Fig. 7) can also be useful in distinguishing different oil types, although it is far from definitive. Lacustrine oils tend to have a bio- modal to broad n-alkane distribution due to input of C15- C19 and C23-C33 n-alkanes from non-marine algae (Gelpi etal,1970; Moldometal., 1985) and have low Pris- tanelnC17 ratios. Marine oils usually show a decreasing concentration of higher molecular weight n-alkanes (low wax content) and Pristane/nC17 ratios < 1.0. Fluvio-del- taic (terrestrial) oils usually show a broad n-alkane distribut- ion or a predominance of waxy (C20+) n-alkanes and Pristane/nC17 ratios > 1.0. Carbon Isotopes
Carbon isotopes on whole oil, saturate, aromatic and other fractions of the crude oil have been used to differ- entiate marine oils from terrestrial oils. But, Sofer (1984) showed that this was invalid, based on a statistical analysis of a wide range of oils of known source. However, Sofer demonstrated that marine oils could be distinguished from terrestrial oils based on a Canonical value (G) calculated from the saturate and aromatic fraction carbon isotope values (Table 3). In fact the Cv value differentiates algal sourced oils, marine or nonmarine ((3 < 0.47), from ter- restrial (fluvio-deltaic) sourced oils (Cv > 0.47).
Pyrolysis-GC Pyrolysis-GC on the oils asphaltenes is a relatively new,
100
and to some extent experimental technique. The idea behind the analysis, is that asphaltene molecules are small kerogen molecules and representative of the original kero- gen in the source rock (Pelet et aL, 1986). Pyrolysis-GC of the asphaltenes can then be used to identify the original kerogen type of the oil’s source rock, based on the general distribution of hydrocarbons on the pyrogram. This can then be used to characterize the oils into different oil types (Fig. 8). Also the relative n-octene, m+p xylene and phenol content of the oil’s asphaltenes can be quantified and plotted on a Ternary diagram. (Fig. 9, modified after Larter, 1985) to determine oil type and the kerogen type of the source rock. The pyrolysis-GC on the oil’s asphal- tenis is performed at 550OC.
A typical lacustrine oil pyrogram (Fig. 8) shows well developed alkenes/alkanes doublets from C5-C35,with part- icularly high concentrations of C15-C30 n-alkenes/n-al- kenes derived from non-marine algae. Characteristicly aromatics and phenolic compounds are virtually absent from the pyrogram. A typical marine oil asphaltene frac- tion pyrogram shows a decreasing concentration of n-al- keneln-alkane doublets with higher molecular weight and moderate concentrations of aromatics and phenols. A flu- vio-deltatic oil shows a broad n-alkene/n-alkane distribution and contains the highest concentration of aromatics and phenols out of all the oils. Prist-l-ene also tends to be high in fluvio-deltaic oils.
A plot of the oil’s n-octene, m+p xylene and phenol content (Fig. 9) can clearly distinguish lacustrine oils from fluvio-deltaic oils. But marine oils, probably due to lack of data, cannot be distinguished from lacustrine oils. Oils pre- sumed to be from lacustrine sources in the West Natuna Basin and some of the oils in the Sunda Basin plot away from the deep lacustrine oils of Central Sumatra. This may be due to deposition of the oils’ source rock in a different lacustrine depositonal environment than that proposed for Central Sumatra. Possibly it was shallower and/or more saline?
GC-MS Biornurker Data
Lacustrine, marine and fluvio-deltaic oils in Indonesia can be distinguished based on Triterpane (m/z 191) and Sterane content (m/z 217). Other biomarkers can also be used such as Bicyclics (m/z 123), Isoprenoids (m/z 183), and Mono and Tri-aromatic Steranes (m/z 253, 231) but are not discussed here. Although it should be noted that the aromatic biomarkers are normally used as a maturity parameter, rather than as a correlation/depositional en- vironment tool.
mterpanes mfz 191 Triterpanes (m/z 191) are broadly similar for all oil
types as bacterially derived 17d hopanes and moretanes are always present in oils (Fig. 10). Deep lacustrine sourced
oils in Indonesia tend to have simple Triterpane distribut- ions containing only pentacyclic 17d hopkes from C27- C35 plus moretanes and little else. The Tm/Ts ratio, which is maturity and organic facies influenced, is usually less than 1.5 and Tricyclic Terpanes (not shown) are in low con- centrations or absent.
Marine oils also have relatively simple hopane and mo- retane distributions, but in Indonesia tend to have high concentrations of C3 1 -C35 hopanes.. This is possibly due to deposition of the source rock in an anoxic calcareous environment, with high bacterial activity. Tm/Ts values tend to range from 3.0 to 1.0. In Indonesia 18doleanane is often in relatively high concentrations in these marine derived oils (Phoa and Samuel, 1986). This is thought to be due to transportation of resistant higher plant resins into the marine basin and not indicative of a terrestrial source for the oil. Noticeable other C30 resin derived compounds, commonly found in association with la oleanane, are absent or in very low concentrations. Marine oils also tend to have relatively high concentrations of tricyclic terpanes. Fluvio-deltaic oils have very characteristic Triterpane dis- tributions with high concentrations of C30 higher plant resin derived cyclic alkanes and the C30 compound 18d oleanane. This is in addition to the normal range of hopanes and moretanes. The C30 derived compounds show charact- eristic peaks on the m/z 191, 163, 177,217,259 and 412 mass ion scans (Fig. 11). Tm/Ts ratios in terrestrially de- rived lndonesian oils tend to be relatively high and range from 6.0 to 1 .O.
Steranes mfz 21 7 Steranes relative to hopanes tend to be in low concen-
trations in non-marine oils, whether they are lacustrine or fluvial-deltaic in origin (Table 3). Typically sterane/l7d hopane ratios are <0.2 in non-marine oils and X . 2 in marine oils (Moldowan etal., 1985). Due to the low con- centration of steranes, it can be difficult to obtain good sterane (m/z 217) scans in non-marine oils unless the GC column of the GC-MS is overloaded.
Deep lacustrine oils usually contain the full range of C27-C29 steranes and diasteranes (Fig. 12), albeit in very low concentrations, and usually have a roughly equal con- centration of C27 and C29 steranes (Table 3). However, a characteristic of deep lacustrine oils in Indonesia is the unusually high concentration of C30 4-methyl steranes in many of the oils. These can be identified from m/z 231, 414 scans and are also present on the m/z 217 scan (Fig. 13). These compounds are believed to be derived from di- noflagellates (Wolf et al., 1986; Brassel et al., 1986) but are also probably derived from non-marine planktonic algae.
Marine oils contain a full range of C27-C29 steranes and diasteranes (Fig. 12), which are usually seen in marine
101
oils around the world. The Salawati Basin oils show similar Triterpane and Sterane distributions to oils in the Mara- caibo Basin of Venezuela (Fig. 14). These oils are sourced from the Cretaceous La Luna Formation which is an or- ganic rich carbonate (Talukdar etal., 1986). This would suggest a similar type of source rock may have generated at least some, of the Salawati Basin oils (klamogun carb- onates and shale?).
Fluvio-deltaic oils have a very characteristic m/z 217 Scan usually containing only C29 steranes and diasteranes (Fig. 12). The dominant compounds on the scan are C30 resin derived cyclic alkanes, which are also present on the m/z 191 triterpane scan. A comparison of triterpane and sterane distributions (Figs. 15 and 16) of fluvio-deltaic oils from South Sumatra, Kutei and Tarakan Basins shows little variation between them, suggesting the organic facies and original higher plant input is similar in all these basins. A plot of C27-C29 sterane composition (Fig. 17) can dif- ferentiate lacustrine/marine oils from fluvio-deltaic oils, but cannot seperate lacustrine and marine oils from each other.
CONCLUSIONS
1) The source rocks of Indonesia can broadly be classi- fied into lacustrine (non-marine algal), marine (marine algal) and fluvio-deltaic (terrestrial). Although signifi- cantly more oil/source rock correlation work needs to be done or published to confirm the source rocks of many Indonesian oils.
2) The identified source rocks are of Tertiary age, although Pre-Tertiary source rocks are probably generating oil in some parts of Eastern Icdonesia.
3) Crude oils can be characterized as lacustrine, marine or fluvio-deltaic sourced oils based on a combination of geochemical data. This includes standard bulk data, Carbon Isotopes, Pyrolysis-GC of Asphaltenes and GC- MS biomarker analysis. Lacustrine oils need further work to subdivide deep, fresh water lacustrine oils from shallowlsaline lacustrine oils.
4) Suspected Pre-Tertiary sourced oils should be analysed and classified to see what type of oils they are and if they show any differences, (particularly in biomarker distribution) from their environmentally equivalent Tertiary oils.
ACKNOWLEDGEMENTS
The author wishes to thank the management of P.T. Corelab Indonesia for permission to publish this paper and Mr. Kamaludin who performed the Pyrolysis-GC Analyses on the oils.
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Woodside, P.R. 1984. A look at the Petroleum Geology of
26 1-280.
BjorGy, M.) John Wiley, 156-163. Indonesia. Oil and Gas Journal, Feb., 78-82.
103
TABLE 1 SOURCE ROCKS OF INDONESIA
HYDROCARBON BASIN* MAJOR SOURCE AGE DEPOSITIONAL ORGANIC GENERAL SOURCE ROCK PRODUCTIVE TYPE ENVIRONMENT FACIES OIL TYPE REFERENCE BASINS OF SOURCE ROCK
North Sumatra Foreland
Foreland
Foreland
Foreland
Foreland
Foreland
Foreland
Cratonic
Foreland
Foreland
Foreland
Inner Arc
Inner Arc
Foreland
Foreland
Baong shales? M-L.Miccene
Bampo? ) ) - Oligocene-
Bruksah?? ) E.Miocene
Marine
Marine Marine Deltaic
Marine algal/ Terrestrial. Marine algal/ Terrestrial Terrestrial/Non marine algal
Non-marine algal
Gas/Lght 01 Situmeang and DavIes, 1986 Soeparjadi 1983 Kingston, 1978
Central Sumatra Pematang Eocene- Brown shale Oligocene (major) Coal zone (minor) Sihapas coal E.Miocene and coal shale
Pematang brown Eocene- shale? Oligocene
Talang Akar Late Oligo- coals/coaly cene-Early shales Miocene
Deep Lacustrine GM. Gravity, Williams et al., waxy, L. 1985 Sulphur Condensatel light oil M. Gravity, Macgregor and McKen-
zie 1986 sulphur L-M. Gravity, Lee, 1982 waxy, L.sulphur M-H Gravity oil, L-Mod. waxy, L. sulphur/ condensate M. Gravity Mob, 1'"s waxy, L. s,ulphur
Bushnell and Atmawan 1986
M. Gravity, Gordon, 1985 waxy, low Wahab and Martono, sulphur 1985 M. Gravity, Soeparjadi et all973 mod waxy, low Russel, 1976 sulphur Bishop, 1980 M-H Gravity, low-mod waxy, low sulphur
M. Gravity, Siegar and Sunaryo, waxy, low sulphur 1980
M. Gravity, Dunand and Oudin waxy, low 1979 sulphur Thompson et al,
1985 M. Gravity, Samuel, 1980 waxy, low sulphur
Pollock et al. 1984
Shallow lacus- trine/marsh-bog Fluviodeltaic
Terrestrial
Terrestrial Central Sumatra (Malacca Straits)
Deep lacustrine
Fluviodeltaic
Non-marlnc algal
Terrestrial South Sumatra
N.W. Java (Sunda)
N.W. Java (Ardjuna Jatibarang) E. Java Sea
Banuwati shales Early Oli-
Talang Akar Oligocene coals/shales -E. Miocene TalangAkar Oligocene- coals/coal y E. Miocene shales Kudjung Oligocene Unit 111 shales and coals?
Barat shales? Late Oligo-
gocene
cene
Deep lacustrhc
Fluvio-Deltaic
Non marlne algal
Terrestrial
FluvIo-Deltaic Terrestrial
Fluviatile Terrestrial
West Natuna
Barito
Kutei
Non-marine algal/ bacterial/terres- trial Terrestrial
Lacustrine
Tanjung coals?/ Eocene shales? Balikpapan Middle coals and Miocene and shales and Younger Younger Deltaics Latin coals and M. Miocene shales? Tarakan and Bu- Pliocene nyu coals and shales?
Fluvio-Deltaic
Deltaic Terrestrial
Deltaic Terrestrial
L-M. Gravity - Low wax, mod- high sulphur
E. Sulawesi (Banggai/Sula)
E. Miocene shales and car- nonates? Jurassic shales and carbonates? Manusela carbonateslcalc shales? Klamogun carbonates1 shales?
Siga shales carbonates?
Tipuma shales? (minor) Ainim coals? (minor) M a t shales? (mdor)
Early Miocene Marine Marine algal
Jurassic Marine
Marine
Marine algal
Marine Akgal? Bula (Seram)
Salawati
Early Jurassic
Late Triassic Early Miocene
Low-M. Gravity O'Sullivan et al., low wax, mod- 1985 high sulphur L-M. Gravity, Phoa and Samuel, low wax, mod- 1986 high sulphur Hughes, 1986
Marine algal/ minor terrestrlal
Oligocene Marine Marine algal/ Minor terrestrial
Terrestrial Bintuni M. Jurassic
Late Permian
LateEarl y Permian
Shallow marine
Fluvial-Deltaic
Shallow Marine
Chevallier and Bor- denave, 1986.
H. Gravity, LOW wax, Low sulphur
Terrestrial
Terrestrial
~~
* Based on Fletcher and Soeprrjadi 1976 ?? Uncertain
Tabl
e 2
CH
AR
AC
TER
ISTI
CS OF
TYPI
CA
L IN
DO
NES
IAN
IMM
ATU
RE S
OU
RCE
ROCK
S
Type
Li
thol
ogy
TOC
Pyro
lysi
s Yie
ld
Ker
ogen
%Oil
Hyd
roge
n K
erog
en
Pris
tane
/ W
t%
SltS2
Type
Pr
one
Inde
x El
emen
tal
Phyt
ane
mg
HC
/p ro
ck
Ker
ogen
H
/C R
atio
of
Ext
ract
Dee
p La
cust
rine
Fluv
io
Del
taic
Mar
ine
Shal
es
Shal
es
and
Coal
s
Shal
es
and
Car
bona
tes
1 .o-10.0
4.0-75.0
Am
orph
ous/
50-100
400-900
Alg
inite
2-1096 (Sh)
6.0-20.0
Vitr
inite
/ 10-30
200-400
40-80%
(Cl)
150.0-300.0
min
or
cutin
ite, r
esin
ite
0.5-5.00
2.0-30.0
Am
orph
ous/
70-100
300-600
Alg
inite
>1.4
1 .O t
o 2.5
0.8-1.0
>3.0
1.2-1.4
<2.5
Tabl
e 3
GEN
ERA
L CH
ARAC
TERI
STIC
S O
F M
AJO
R O
IL T
YPE
S IN
IND
ON
ESIA
API
W
t%
-
Pris -
nC31
6
13C
Cv
Ster
anes
Tm
/Ts
C30
ST
ERA
NES
C
30
Gra
vity
Su
lfur
BY
nC
19
17a H
opan
es
Res
ins
% C
2920
R
4-M
ethy
l C
2920
R+C
2720
R
Ster
anes
Dee
p La
cust
rine
20-3
5 43
.2
3.0-
1.5
>0.4
<0
.47
~ <O
.2 1.
50-0
.20
LOW
<6
5%
LOW
-Hig
h
Fluv
io-
Del
taic
30
-50
<9.2
>3
.O
X.4
>0
.47
<0.2
6.
0-1.
0 V
.hig
h 10
0%
Low
-Abs
ent
Mar
ine
20-3
0 >0
.2
2.5-
1 .O
<0.4
<0
.47
>0.2
3.
0-1.
0 Lo
w-A
bsen
t <5
0%
Low
-Abs
ent
Pris
=
Pris
tane
Ph
Y =
Phyt
ane
6 13C
C,
= So
fers
(198
4) C
anon
ical
varia
ble
Tm =
C27
17a
Tris
norh
opan
e Ts
=
C27
18aT
risno
rhop
ane
cv
= -2
.53
6 13
Csa
t+ 2
.22 6 1
3Ch0
- 1
1.65
106,
a m o m ~a * w a - >
a z ~
0 m a a 0 0 cr c3 >. I w I l-
Y . 0 2 0
0 - - a J
W w w
3-
0 t
107
CENTRAL SUMATRA LACUSTRINE SOURCE ROCK DEPOSITED IN HALF GRABEN RIFT BASIN
, . .. . +, .. . ,-
EN ECHELON , G R A B E N S
B A L A M AND RANGAU B A S I N S
C E N T R A L S U M A T R A
+ + f t
+ + +
t + + + + c + +
n- GRABEN (MIDDLE EOCENE): RAPID BLOCK- ROTATION, D E V E L O P M E N T O F D E E P ANOXIC L A K E WITH SLOW DEPOSITION O F PEMATANG BROWN S H A L E F O R M A T I O N .
A f t e r Williams e t .al 1985
FIGURE 2
W
”
0
M
109
RELATIONSHIP O F O I L P R O N E SOURCE R O C K T O MODERN D E L T A I C ENVIRONMENT
FIGURE 4
110
I I
l l7OE \ 118OE I
119 O E
+ 2.s
0 a5 6 0 K m
+
HANDIL F I E L D -ssw
119.E L...
I I SCALE Il’lOE I l 8 O E
I
LEGEND
mi BACK DELTA PLAIN PRODELTA W I T H FAIR SOURCE ROCKS
MARINE SHELF DELTA PLAIN WITH VERY GOOD SOURCE ROCKS
DELTA FRONT After Thomron a t 01 1985. ond Moanior at 01 19T5)
FIGURE6 - D E L T A I C MIOCENE SOURCE ROCKS - K U T E I BASIN
'.
GE
NE
RA
LIZ
ED
M
I o c
E N E
P
AL
E'O
G E
O G
R A
P H
IC M
AP
--
a
10
20 Km
OF
f
14
Mo
dif
ied
fro
m G
ibso
n - R
ob
inso
n 1
98
6 1
k--
.-..
S
AL
AW
AT
I B
AS
IN '
SU
GG
ES
TE
D
DE
PO
SIT
ION
OF
MA
RIN
E S
OU
RC
E
RO
CK
SA
LA
WA
TI
BA
SIN
F
lGU
RE
6
c
c
c
112
z 0
0 n
n c)
z m
0
0 m
113
P Y R O L Y S I S - G C O F C R U D E OIL A S P H A L T E N E S
In I
L A C U S T R I N E OIL TYPE I KEROGEN
M A R I N E O I L T Y P E 11 KEROGEN
I0 = n C 10 ALK ENE /ALKANE T = TOLUENE X = m t p XYLENE Pf = P R l S T - I - ENE
P H E N O L S / A L K Y L B E N Z E N E S T 8 X I \ FLUVIO - DELTAIC OIL
TYPE 1II KEROGEN
FIGURE 8
114
P Y R O L Y S I S - G C C L A S S I F I C A T I O N O F CRUDE OIL ASPHALTENES USING D I S T R I B U T I O N O F N - O C T E N E m + p XYLENE A N D
PHENOL
T Y P E III = KEROGEN T Y P E
*. MAR INE OILS (SALAWAT1,SULAWESI)
N OCTENE 100 Y o
Deep Lacustine Oils
Sunda Basin 1
Shallow Lacustine Oils (W.Natuna /Sunda Basin)
Fluvio - Deltaic Oils [N .W. Java ,East Java, Kutei ,Tarakan ,
T Y P E 111
100 ./a PHENOL too O/O
M.P. XYLENE
FIGURE 9
L L - 0
115
w w k!
It II I t t i II
I
o a a > j i -
0
116
F L U V l O - DELTAIC OILS - IDENTIF ICATION O F RESIN C 3 0 CYCLIC A L K A N E S
R
B
1 IR
C 2 9
2 9 n
30
M / Z 191 TRITER PAN ES R = C 30 CYCLIC ALKANES
OL = l a d O L E A N A N E C 3 0 = H O P A N E S
Ts,Tm= C 2 7 H O P A N E S
M / Z 217 STERANES 2 9 - S T E R A N E S
M / Z 163
M / Z 412 C 3 Q PARENT IQN
,C30
DERIVED
FIGURE 11
LA
CU
ST
RIN
E O
IL
TY
PE
I K
ER
OG
EN
'N 2
17
.00
-C
29
M
/CB
OM
l I
-._
. .
. . .
. I-----,
B 4
1
42
4
3
44
4
5
46
4
?
48
4
9
50
MA
RIN
E
OIL
T
YP
E I1 K
ER
OG
EN
D
-.
. 27
2
8
2 9
30
3
1
32
33
34
3
5
36
3.'
CR
UD
E O
IL T
YP
ES
OF
IN
DO
NE
SIA
S
TE
RA
NE
S M
I2
217
LE
GE
ND
C2
7
RE
GU
LA
R S
TE
'RA
NE
S C
29
M/C
30
M-
4-M
ET
HY
L
ST
ER
AN
ES
R
::
C 3
0 R
ESI
N D
ER
IVE
D C
YC
LIC
AL
KA
NE
S
. C
27
I - DIAS
TE
RA
NE
S
FL
UV
lO -D
EL
TA
IC
OIL
T
YP
E 11
1 K
ER
OG
EN
R
rc
2
0 R
I
FIG
UR
E 1
2
118
LACUSTRINE OIL *IDENTIFICATION O F C 30 4-METHY L STERANES FROM M / Z 217,231 AND 414 IONS
ION 217.00
M E T H Y L ERANES
I ! O N 414.00 I l l I 4oJ
30-
ao-
119
4 m N
r- N
W z a
-I 0
v ) - W I -
-
J 0
r n d w o z a -
J 0
0 m
m
N
W
w H I-
t 0 t- z W t w
-
-
a
4 00-
38
8-
191.2
0
1
KU
TE
l B
AS
IN
OIL
600-
500-
400-
30
C3
I
30
0-
200-
100-
10
20
30
40
ION
1
91
.20
4 00
TA
RA
KA
N
BA
SIN
L
OIL
c2
9 t C
30
,CJI
0’ .
28
3e
48
50
6 0-
c
t4 0
CO
MP
AR
ISO
N O
F T
RIT
ER
PA
NE
S (
M/Z
191
1 IN
S
OU
TH S
UM
ATR
A , T
AR
AK
AN
A
ND
K
U T
E I
BA
SIN
F
LU
VIO
- D
EL
TA
IC
SO
UR
CE
D O
ILS
LE
GE
ND
C2
9
= H
OP
AN
E
Tm
/Ts
: C
27
HO
PA
NE
R
= C
30
RE
SIN
DE
RIV
ED
CY
CL
IC A
LK
AN
E
OL
: 1
8 O
LE
AN
AN
E
24
-4
=
C2
4 T
ET
RA
CY
CL
IC
TE
RP
AN
E
I IO
N 1
91
.20
SO
UT
H
SU
MA
TR
A
OIL
IR RllTn
C 30
FIG
UR
E 15
121
COMPARISON O F S T E R A N E S ( M / Z 217) IN SOUTH SUMATRA, T A R A K A N A N D KUTEI BASIN F L U V I O - DELTAIC SOURCED OILS
R
M / Z 217 T A R A K A N BASIN O I L
LEGEND C 29 = STERANES C 2 9 .I = DIASTERANES R = C 3 0 R E S I N DERIVED
CYCLIC ALKANES
bl/Z 217
R
P
R
c29
ljh
R
S O U T H SUMATRA O I L
bl/Z 217
R
c29 L
K U T E I BASIN O I L
c 2 9
m
FIGURE 10
C2
85
0c
20
R
ST
ER
AN
E C
OM
PO
SIT
ION
OF
IND
ON
ES
IAN
C
RU
DE
OIL
TY
PE
S
( A
C?
cr
Hu
ang
an
d M
ein
sch
ler,
19
79
1
Lac
ust
rin
e /M
arin
e oi
ls
luvl
o - D
el ta
ic o
ils
C2
g5
d2
0R
FIG
UR
E 1
7