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Publication 2015

AAPG/SEG INTERNATIONAL CONFERENCE & EXHIBITION 2015

13-16 SEPTEMBER 2015 MELBOURNE , AUSTRALIA

SEDIMENTOLOGY OF MODERN TROPICAL RIFT BASIN OF LAKE SINGKARAK, ANALOGUE MODEL FOR CENTRAL SUMATERA AND OMBILIN BASINS, SUMATERA, INDONESIA

Bachtiar, A**., Suandhi, P.A.*., Setyobudi, P.T.*., Fitris, F***., Malda, O*., Lesmana, Z*

GDA Consulting* – DEN** – Chevron Pasific Indonesia***
Tebet Timur Dalam X Street No 2, Postal Code 12820 – Jakarta, Indonesia

Abstract ID: 2210852

ABSTRACT

Lake Singkarak is the biggest modern pull apart basin in Indonesia and closes modern analogue model for Central Sumatera and Ombilin Basins. This lake is situated at Solok District, West Sumatera Province. Lake Singkarak was originally developed by active transtensional tectonic regime at one of many compartment of Great Sumatera Fault. This study is aimed to give alternative sedimentology analogue model for fluvio lacustrine environment in tropical area by made similarity comparation between modern to ancient sediment.

Results of comprehensive field sedimentology work showing series of Quaternary Holocene (12,700 – 2,700 years) sediments which are distinguished by particular association of individual facies (10 defined facies) related to fluvio – lacustrine system. Alluvial fan facies was characterized by coarsening sequence pattern of intercalation gravity flow and traction sediments. Braided river facies was characterized by high energy traction sediment at steep slope river with volcanic clastic sediment supply with soil layer at top part. Meandering river facies was characterized by low sinuosity meandering belt with high traction current sediment and fining upward sequence. Fan delta facies was divided become three part, upper, medial and lower which dominantly characterized combination of gravity flow and traction current. Shoreline lacustrine facies was characterized by low energy of wave current creating wash over sediment. Lacustrine delta facies was divide become four sub-facies consisting of delta plain, distributaries channel, and mouth bar. Shallow lacustrine facies was characterized by falling out suspension creating interlaminate of clay, algae, silt and medium grain sand and poorly massive clay. Shelf slope – deep lacustrine facies is distributed from first bathymetry slope (25-35 meter) to the basin floor or deepest part of lacustrine (267 meter). Results of strata box measurement which is integrated with bathymetry survey, gravity coring and sediment grabbing on systematic mechanism showing that this depositional was divided becomes four sub-facies consisting of sub-lacustrine channel and levee complex, sub-lacustrine fan, shelf turbidity and pelagic facies. Shelf – deep lacustrine facies was characterized by high density turbidity and falling out of suspension sediment.

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PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION

Thirty-Ninth Annual Convention & Exhibition, May 2015

BEST PROFESIONAL POSTER PRESENTER

Integrated Study of The Depositional Environment, Structural Geology, Diagenesis, and Petroleum System of The Tertiary At The Southern Border of The Upper Kutai Basin

Andang Bachtiar* Prihatin Tri Setyobudi*  Muhammad Rozalli *  Elly Guritno**  Ari Subekti**  Purnama Ary Suandhi*  Andi Kriyunianto*

*GDA Consulting  ** Salamander (West Bangkanai) Energy Ltd

 ABSTRACT

 The southern border of the Upper Kutai Basin is a semi-mature exploration area in Central Kalimantan which has proven producing hydrocarbons. In 1982, a significant gas and condensate accumulation was discovered in Oligocene Carbonates in Kerendan Field. Most of the seismic data in this area have poor-fair quality. So an integrated study of the surface and sub-surface was needed to get a better petroleum system component potential oversight.

Surface geological mapping and measured oucrop stratigraphy were integrated with well correlations and seismic facies to obtain the depositional environments and overall stratigraphic framework. Burial history analysis from source rock maturity and petrographic analysis were conducted to understand the diagenesis or burial effects within the reservoir and source rock quality. Detailed surface structural geology investigations were integrated with image/landsat and seismic interpretations to valididate structure occurrences and possible reconstruction of the traps.

Syn-rift sediments were developed during Middle to Late Eocene with terrestrial to deltaic environments A bounding fault (southern area), transitions to a marine environments which developed in a flexural margin (northern area). Post-rift sediments were developed during Early to Late Oligocene which were dominated with a marine environment, isolated reefs commonly occur in the northern area, and platform carbonates occur in the southern area. Inversion sedimentation developed in Early to Late Miocene which was dominated with deltaic sediments, where the paleo-shoreline changed from a E-W to a N-S direction. A Post-Inversion stage is developed during Plio-Pleistocene which is composed of mollasic sediments and NE-SW thrust faults.

The primary source rocks are Eocene, fluvial-deltaics (Type II, III, II & III, and matured) and Oligocene marine source rocks. The best reservoirs are Miocene & Eocene fluvial deltaic sandstones and Oligocene carbonates with secondary porosity (fracture and dissolution). Regional seals are Late Oligocene offshore-bathyal shales and intra-formational seals of Eocene and Miocene deltaic sediments. The predominate traps are a combination of stratigraphy and structure which are controlled by NE-SW thrust faults or fold propagated faults.

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PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION

Thirty-Ninth Annual Convention & Exhibition, May 2015

CHARACTERISTICS OF CIBULAKAN MARINE RESERVOIR BASED ON MODERN ANALOGUE IN TELUK NAGA & PARANG TRITIS BEACH, JAVA, INDONESIA

Ari Yusliandi*, Bambang Dodi Hari Sasmita*, Muhammad Arifai*, Muhammad Alfatih Syaifurrohman*, Prihatin Tri Setyobudi*, Andang Bachtiar*, Purnama Ary Suandhi*, Andi Krisyunianto (* GDA Consulting)

 ABSTRACT

Marine deposits make good reservoirs. Cibulakan Formation in Northwest Java Basin is one example of productive reservoir. Teluk Naga and Parang Tritis beach deposits are good example of modern analogue to compare characteristics between the tertiary and recent beach deposits.

This study reviews Cibulakan Formation characteristics based on previous studies including an assessment of sediment composition, texture of material and stratigraphy based on core and outcrops data compared with modern beach sands at Teluk Naga and Parang Tritis.

Cibulakan Formation can be divided into two members, Upper Cibulakan Member and Lower Cibulakan Member. In this study, Upper Cibulakan Member comprises poorly consolidated greenish grey claystone to consolidated shale, containing dispersed silt, quartz sand, pyrite, glauconite, lignitic plant remains, foraminifera and shell fragments. Upper Cibulakan Member was deposited in shallow inner-outer neritic environment.

Parang Tritis is a beach located in southern part of Java Island exactly at Yogyakarta province, Teluk Naga is a beach located in northern part of Java Island exactly at Banten province. Observation of modern sediments on both beaches used pipe coring methods. Data were collected from different places. Characterization of Parang Tritis beach shows more indications of wave dominated deposits than Teluk Naga sedimentological characteristics. The results of this study can be applied to hydrocarbon exploration based on the analogue between recent sediment and Tertiary formation.

Keywords: Marine reservoir, Cibulakan Formation, Northwest Java Basin, Teluk Naga, Parang Tritis, Reservoir Characteristics, Modern Analogue.

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