7-sumatra-petroleum-geology.pdf

Petroleum tr oleum Geolo Geology gy of Indonesia ndo nesia : Current Know K nowle ledge dge Regular HAGI AGI Course Yogya ogy akarta, karta, 2 – 6 August Aug ust 2010

7. SUMA SUMATR TRA A Minangka inangkaba bau u architecture

by : Awang Aw ang Harun Harun Satyana Satyana

SUMATRA

Simandjuntak and Barber (1996)

SUMATRA MAJOR TECTONIC ELEMENTS • The Sunda Shelf borders the back arc basin to the east • Asahan Arch, Bukit Tigapuluh Mountains and Lampung High partitions the back-arc basins • The Bukit Barisan Range : Neogene Magmatic arc, separates the back-arc basins from West Sumatra forearc basins • The Outer Arc Islands : accretion wedges • The Sumatra trench: an oblique subduction zone

SUMATRA BACK ARC BASIN MODEL

Koesoemadinata (2006)

Sumatra Pre-Tertiary Basement • Pre Tertiary rocks are exposed in the Barisan Range, Tigapuluh Mountains and Lampung High. • Sumatra Pre-Tertiary rocks have been analyzed into separate terranes consisting of :  – highly tectonized Paleozoic and Mesozoic terranes  – Paleozoic to Mesozoic intrusive rocks  – Melange (ophiolitic rocks). • Pre-Tertiary terranes are interpreted as a collage of  Asian and Gondwanan microcontinents.

Microplate boundaries

Pertamina and Beicip (1985)

SUMATRA TERTIARY BASINS • Back-arc and partly fore-arc basins are underlain by continental crust. • The magmatic arc, Barisan Range, uplifted Pre-Tertiary rocks forms border to the basins. • Paleogene rift basins extend from back-arc to fore-arc basins across the Bukit Barisan. • Volcanism is limited to Paleogene (in the Southwest) and Plio-Pleistocene. • The presence of the Great Trans-Sumatra wrench fault (Semangko Fault) along the Bukit Barisan.

North Sumatra Basin 

Central Sumatra Basin 

South Sumatra Basin 

Sedimentary basins of Sumatra

Stratigraphy of Sumatra back-arc basins

Samuel and Gultom (1986)

Sumatra Tectono-Stratigraphic System From top to base : • Syn-orogenic deposition in a back-arc basin : regressive (Mid-Miocene-Recent)  – rising Barisan Range clastic source • Post-rift deposition in a shelfal basin : transgressive (Early Miocene)  – Sundaland clastics source and carbonates • Syn-rift deposition in active rift-valley basins : one or more rift phases (?Eocene-Oligocene)  – local clastic source

Sumatra Major Fault System • THE TRANS SUMATRA STRIKE-SLIP FAULT SYSTEM : active since Early Tertiary times • THE PALEOGENE BASEMENT FAULT SYSTEM :  – This fault system resulted in the Paleogene graben-half-graben system with syn-rift deposition  – The Sumatra Paleogene Fault System extends SE to the NW Java basinal area

Sumatra Fault System

The Paleogene Basement Fault System • This fault system consists of two main components  – N-S component  – WNW-ESE component  – In South Sumatra a NE-SW component is present

• This fault system cuts clear across the Barisan Range, beneath the fore-arc basin. • This fault system is responsible for the development of Paleogene graben- halfgraben basin system with syn-rift deposition forming important oil kitchens.

Murphy (2000)

Sumatra Paleogene Fault System

Koesoemadinata (2006)

Paleogene Basement Faults Explanation • Moulds (1989): Faults are mainly N-S and was created due to the E-W directed extensional regime during the initial stage of the N-S directed stress caused by the subduction. • Other explanation: transtensional faults due to the dextral wrenching movements of the Indian Ocean Plate relative to the Sunda continental plate

The Neogene Fold system • The fold system is dominated by the WNW-ESE trending anticlinoria. • Generally forming an en-echelon pattern. • Explanation:  – Wrench movement along the NW-SE basement faults (related to the Paleogene graben system) (Harding,1988)  – Draping over uplifted blocks due to compressive regime of the subduction (Moulds, 1989)

North Sumatra Basin •

The basin is notable for the first commercial oil field‐ the Telaga Said field (discovered 1885) and the giant Arun gas field.

•

The basin is extremely large and extends from  just north of  Medan northwards for several hundred kms into the Andaman Sea and across the Thailand‐ Indonesia border.

•

The Indonesian sector of  the basin is bordered to the west by the Barisan Mountain thrust system and to the east by the stable Malacca platform.

•   Onshore sector of  the basin has been extensively explored, however, remaining

potentials include : gas‐filled Peutu carbonate buildups, Belumai buildups on the Malacca shelf, Baong and Keutapang stratigraphic play, lowstand turbidite‐fan systems of  middle Miocene (Tsukada et al., 1996; Nur’aini et al. 1999), latest Oligocene Bampo fan systems, syn‐rift Parapat in graben deeps, Eocene Tampur carbonates (Ryacudu and Sjahbuddin, 1994). •   Relatively unexplored northern deepwater (> 1000 m water depth) sector of  the

basin merits further investigation.

NORTH SUMATRA BASINAL AREA

Koesoemadinata (1994)

North Sumatra Crustal Section

Koesoemadinata (1994)

North Sumatra Basin

Pertamina and Beicip (1985)

Generalized physiography and productive HC discoveries of the North Sumatra basin

Netherwood (2000)

Cross section across Barisan uplift and Southern NSB

Pertamina and BPPKA (1996)

Cross section across North Sumatra Basin Pertamina and BPPKA (1996)

Cross section across NE corner of Barisan uplift

Pertamina and BPPKA (1996)

North Sumatra Eocene Basin Configuration

Davies (1984)

North Sumatra Basement Eocene

Davies (1984)

North Sumatra Basin Oligocene Development

Davies (1984)

North Sumatra Basin : Miocene

Davies (1984)

North Sumatra Basin : Pliocene

Davies (1984)

North Sumatra Basin : Present

Davies (1984)

Pertamina and Beicip (1985)

Stratigraphic nomenclature of North Sumatra Basin

Caughey and Wahyudi (1993)

North Sumatra Stratigraphy

North Sumatra Stratigraphic Diagram

Synorogenic

Post-rift

Syn-rift Syn-rift

ENI (2002)

Chronostratigraphic scheme for northern part of the North Sumatra Basin

North Sumatra Petroleum System • Source Rocks and Migration • Reservoir Rocks  – Clastics : Belumai Sands, Baong Sands, Keutapang, Seurula sands  – Carbonates : Early Miocene Reefs

• Seals • Trapping Conditions  – Stratigraphic  – Structural

ENI (2002)

Stratigraphy and Petroleum System of North Sumatra Basin

Petroleum system of North Sumatra basin

Pertamina and BPPKA (1996)

Pertamina and BPPKA (1996)

BAONG

Pertamina and BPPKA (1996)

Pertamina and BPPKA (1996)

Pertamina and BPPKA (1996)

ENI (2002)

Deepwater North Sumatra Basin

Central Sumatra Basin • The Central Sumatra Basin is the most prolific oil basin in SE Asia. Reserves estimates for the basin of 13 BBOE ultimately recoverable, of which 2.5 BBO remain to be recovered (Sujanto, 1997). • The basin is mature with respect to HC exploration with a simple and essentially single petroleum system operating. • New ideas are required if further fields are to be discovered and trend of declining production to be halted.

Basement tectonostratigraphic map

Pertamina and BPPKA (1996)

Basement tectonostratigraphic correlation chart

Pertamina and BPPKA (1996)

CENTRAL SUMATRA BASINAL AREA

Central Sumatra Basinal Area Regional Seismic Section

Central Sumatra Basin

Pertamina and Beicip (1985)

Central Sumatra Rift Basins

Central Sumatra Paleogene Rift Basins

Eocene – Oligocene F1 (45 Ma-26 Ma) regional structure map

Pertamina and BPPKA (1996)

Miocene – Recent F2-F3 (26 Ma-0 Ma) structure map

Heidri ck and Auli a (1993)

Mertosono and Nayoan (1974)

Central Sumatra tectonostratigraphic chart

Pertamina and BPPKA (1996)

Stratigraphic nomenclature of Central Sumatra Basin

Wain and Jackson (1995)

Central Sumatra Stratigraphic Diagram

 At las IPA (1991)

Central Sumatra Chronostratigraphy

Central Sumatra Petroleum System • Central Sumatra is the most prolific petroleum in the Indonesian Basin. • Source rocks and oil kitchen are exclusively synrift deposits (Brown shales of the Pematang Group). • Reservoirs are exclusively clastics of the post rift transgressive Sihapas group. • Trapping is provided by structural traps with stratigraphic components.

Central Sumatra petroleum system events chart

Central Sumatra Basinal Area Miocene Duri Delta

Cross plot of TOC and hydrogen index (HI)

Kerogen assemblage dominated by fluorescent amorphinite (A) and degraded, freshwater Botr yococcus (FWA) in Brown Shale formation, Central Sumatra basin. Netherwood (2000)

Brown shale isopach map in Pematang trough

Pertamina and BPPKA (1996)

Central Sumatra regional heat flow map

Paleogene depocenters, generalized structure and oil field distribution for the Central Sumatra basin

Prapton o et al. (1991)

Field distribution along regional, north-south trending dextral transcurrent faults in the coastal plains block of Central Sumatra

Heidrick and Aulia (1993)

Netherwood (2000)

Sihapas reservoir of Bekasap formation in Minas field

Central Sumatra Oil Fields • Gas fields are practically non-existence • Minas and Duri field are the main oil fields and can be classified as giant field.

F2 – F3 Duri field and seismic profile

F2 – F3 East Kayuara field and seismic profile

F2 – F3 Kotabatak field and seismic profile

F2 – F3 Lalang field and seismic profile

F2 – F3 Libo SE field and seismic profile

F2 – F3 Lirik field and seismic profile

F2 – F3 Melibur field and seismic profile

F2 – F3 Minas field and seismic profile

F2 – F3 Parum field and seismic profile

F2 – F3 Petani field and seismic profile

South Sumatra Basin • The basin contains diverse petroleum systems, with both oil and gas being sourced from lacustrine and fluvio-deltaic terrestrial facies. • Limited potential still remains for the traditional Talang Akar  and Batu Raja formation plays. • In contrast to the basin’s mature oil status, the South Sumatra Basin is under-explored for gas, and contains good remaining gas potential in both new and existing successful plays. A further 6 to 10 TCF gas could be discovered in the basement, Talang Akar, and Batu Raja.

SOUTH SUMATRA BASINAL AREA

Koesoemadin ata (1994)

South Sumatra Crustal Cross-Section

Koesoemadinata (1994)

South Sumatra Basin Outline

SOUTH SUMATRA BASINAL AREA • JAMBI SUBBASIN • NORTH PALEMBANG SUBBASIN • CENTRAL PALEMBANG SUBBASIN • SOUTH PALEMBANG SUBBASIN

South Sumatra structural framework

Pertamina BPPKA (1996)

South Sumatra Basin

Pertamina and Beicip (1985)

South Sumatra Sub-Basins

South Sumatra Paleogene Graben‐ Halfgraben System

South Sumatra Paleogene Graben System • The gra graben ben syste stem is is mor more e co comple mplex x th than else else where in Sumatra. • In addi additi tion on to the the N-S N-S-N -NWW-SE SE syst system em ther there e is is an an additional NNE-SSW set. • It con consi sist sts s main mainly ly of of half half-g -gra rabe bens ns,, faci facing ng wes westt as well as east. • The hal halff-gra graben bens are in invert erted wit with NW NW-SE set turning turning into into a thruste thrusted d fold fold belts, belts, descri described bed as “flower structure”. Ryacudu Ryacudu (200 (2005) 5)

Jambi Graben System • A NNE-SSW complex gr graben system. • Unique among the SW Sunda graben being not N-S oriented. • Due Due to to ext exten ensi sion on phas phase e fol follo lowi wing ng a pre pre-e -exi xist stin ing g major basement fault extending from Bukit Bari arisan san to Si Sin ngkep gkep Island. and. • This gra graben ben system tem becom ecomes es the site of the huge huge Jambi Jambi Depre Depressi ssion on in the the Neogen Neogene. e.

South Sumatra Basin Tectonic Development (1) west

east

South Sumatra Basin Tectonic Development (2) west

east

Yulihanto ulihanto and Sosrowidjoyo osrowidjoyo (1996)

Generalize neralized d struct str uctural ural pa p attern of South out h Sumatra Basin

Basement terrains of South Sumatra Basin

Ginger and Fielding (2005)

Structural styles of South Sumatra Basin

Ginger and Fielding (2005)

South Sumatra surface structu res

Pertamina BPPKA (1996)

Stratigraphic Correlation of Central and South Sumatra Basins

De Coster (1974)

Pertamina and Beicip (1985)

South Sumatra Stratigraphic Diagram

 Atl as IPA (1991)

South Sumatra Petroleum System • Source Rocks and Oil Kitchens • Migration • Reservoir Rocks :  –  –  –  –  –

• • • •

Basement Talangakar sands Baturaja carbonates Air Benakat sands Muara Enim sands

Seals Trapping Condition Structural Traps Stratigraphic Carbonate Build-ups

South Sumatra Oil and Gas Fields (Examples of Fields) • Fractured basements : Suban, Sumpal, Sambar. • Talangakar sandstones : Talang Akar, Pendopo, Benakat, Limau fields, some fields in Jambi. • Baturaja carbonates : Ramba, Air Serdang, KajiSemoga. • Air Benakat sandstones : old fields, Kampong Minyak, Rambutan. • Muara Enim sandstones : old fields

Exploration history of the South Sumatra Basin Ginger and Fielding (2005)

Cummulative discovery curve for the South Sumatra Basin split by reservoirs Ginger and Fielding (2005)

Kerogen of South Sumatra Basin Netherwood (2000)

Present day maturity map on top basement

Ginger and Fielding (2005)

Netherwood (2000)

Pertamina and BPPKA (1996)

Pertamina and BPPKA (1996)

Pertamina and BPPKA (1996)

Suban giant gas field : producing gas from multiple reservoirs (igneous-metamorphic rocks, siliciclastics and carbonates) Pujasmadi et al. (2002)

Depth st ructur e map of top Baturaja Formation

Stratigraphy of South Sumatra Basin

Kaji-Semoga field : big discovery in an over 100 year explored-basin Hutapea (2002)

Leached skeletal packstone of Baturaja carbonate

Oil groupi ng of South Sumatra Basin

Ginger and Fielding (2005)

Intra-Arc Basins of Sumatra

OMBILIN

PASEMAH

Darman and Sidi (2000)

Ombilin Rift‐Basin Early Stage

Ombilin Basin Central Sumatra Middle Stage

Ombilin Basin, Central Sumatra Late Stage

Stratigraphy of Ombilin Basin, West Sumatra

Kamal (2000)

Tectonic setting of Pasemah Block, South Suamtra

Kamal (2000)

Subsurface stratigraphy of Pasemah Block, South Suamtra

SUMATRA FORE-ARC BASINS • Meulaboh Basin • Sibolga Basin • Mentawai Basin • Bengkulu Basin Western Sumatra fore-arc basin are still underlain by continental crust, and Paleogene graben system extends underneath the Neogene fore-arc basin.

Fore-arc Basins •

Fore-arc basins have traditionally prospective for hydrocarbons due to :

been

considered

poorly

 – source-rock facies were unlikely to develop in these essentialy shallow, oxygenated, open-marine basins,  – Reservoir quality was assumed to be problem because nearby volcanic arcs and melange complex have supplied a predominance of poor-quality reservoirs,  – Geothermal gradients are relatively low. •

Six fore-arc basins of Western Indonesia have been drilled : Banyumas, South Central Java, Southwest Java, Bengkulu, Mentawai, Sibolga. The results, in some way, fuel optimism for the existence of economic petroleum reserves in the Western Indonesia fore-arcs.

West Sumatra Basin Petroleum System • The fore-arc basins are considered “cool basins”. • The fore-arc basins are less likely to contain hydrocarbons. • Oil and gas occurrences are sourced from the synrift deposits, which experienced heating during the rifting process.

Simplified map of structural elements and HC occurrence in the Sumatra forearc

Yulihanto et al. (1995)

Bengkulu-Mentawai-Sibolga Basins (1) •

The Bengkulu basin is the mostwidely explored fore-arc basin in Indonesia. All Bengkulu basin carbonate targets proved to be waterfilled. Arwana-1 (Fina, 1992) encountered good oil shows and penetrated good marine sources of Oligo-Miocene shales which are within the oil window with GG of 4.5-5°C/100 m (this is significantly higher than normal fore-arc setting). The origin of the Bengkulu basin is not strictly fore-arc, may originally have been in back-arc setting (Howles, 1986; Mulhadiono and Asikin, 1989; Hall et al., 1993; Yulihanto et al., 1995).

•

The Bengkulu basin has a proven petroleum system for oil generation. It demonstrates a similar geology to the South Sumatra basin, with an undrilled Paleogene rift system that could feasibly contain lacustrine source rocks, and proven post-rift reservoir facies. Post-rift Miocene shales and some coals are proven source facies.

Bengkulu-Mentawai-Sibolga Basins (2) •

Fieldwork in the Mentawai Islands shows that the marine Oligocene graben fill in the Mentawai basin has source potential. Basin modelling suggests that these sediments may have entered oil window as early as the middle Miocene. Early Miocene buildups are considered potential reservoir target. Some wells contain biogenic methane shows (Yulihanto and Wiyanto, 1999).

•

Suma-1, Singkel-1 (Union Oil), and Ibu Suma-1 (Caltex) wells of Sibolga basin encountered sub-economic quantities of biogenic gas (Dobson et al., 1998) middle Miocene carbonate build ups. The traps have sealing problem. Interbedded sands may show better biogenic gas prospects.

Bengkulu Basin Rifting

Yulihanto et al. (1995)

Yulihanto et al (1995)

Stratigraphy of Bengkulu fore-arc basin

Bengkulu Basin Stratigraphic Column Manna Subbasin

Yulihanto et al (1995)

Tectonic setting of Bengkulu fore-arc basin

Yulihanto (2000)

Stratigraphy of Mentawai fore-arc basin

Yulihanto (2000)

Subsurface stratigraphy of Mentawai fore-arc basin

Stratigraphy of Nias, Sibolga fore-arc basin

vid e Murphy (2000)

Seismic secti on and interpretation o f the middle Miocene Ibu Suma buildup, Sibolga basin, north Sumatra fore-arc