THE SYNRIFT FACIES DISTRIBUTION MODELING OF PRE-NGIMBANG AND NGIMBANG FORMATIONS AND ITS IMPLICATION TO THE HYDROCARBON EXPLORATION IN LAUT BALI TIMUR AREA EAST JAVA-LOMBOK BASIN
THESIS
As one of the requirements to achieve a Master degree from Institut Teknologi Bandung
By
YUYUS KUSNANDAR NIM: 22006015 (Geological Engineering Graduate Studies Program)
INSTITUT TEKNOLOGI BANDUNG 2009
THE SYNRIFT FACIES DISTRIBUTION MODELING OF PRE-NGIMBANG AND NGIMBANG FORMATIONS AND ITS IMPLICATION TO THE HYDROCARBON EXPLORATION IN LAUT BALI TIMUR AREA EAST JAVA-LOMBOK BASIN
By
Yuyus Kusnandar NIM: 22006015 (Geological Engineering Graduate Studies Program)
Approved by Advisors Committee Date: ………………………
Advisor I
Advisor II
( Dr. Dardji Noeradi )
( Benyamin Sapiie, Ph.D )
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ABSTRACT
THE SYNRIFT FACIES DISTRIBUTION MODELING OF PRE-NGIMBANG AND NGIMBANG FORMATIONS AND ITS IMPLICATION TO THE HYDROCARBON EXPLORATION IN LAUT BALI TIMUR AREA EAST JAVA-LOMBOK BASIN
Yuyus Kusnandar NIM: 22006015
East Java-Lombok basin is one of the promising exploration targets for synrift plays. However, although all the required ingredients for hydrocarbon accumulation found in the area, in fact the exploration success ratio is relatively low. The previous studies suggested that in general the dry holes in East JavaLombok Basin were mostly caused by the migration problems due to the absence or lack of communication between reservoirs and source rock in the area. The synrift sandstone deposit of Ngimbang and Pre-Ngimbang Formations is considered to be the main migration carrier bed and in some cases it is also act as the active reservoir (L46-1 well & Pagerungan field). While the synrift lacustrine shale act as the hydrocarbon main source rock and some act as the seal. So it is very important to understand the synrift facies distribution in this area, in order to reduce the migration uncertainty, predicting the reservoir geometry and other general implication to the hydrocarbon exploration in this area. This research is designed to generate the facies distribution model of synrift deposit by using the 3D geo-cellular modeling technique which integrated the existing well and seismic data with a fine conceptual geological model from the present day analogues. The research is divided in to five main steps; the rift basin identification and reconstruction, the synrift depositional units division, the lithology recognition from the well vs. seismic attributes, the facies distribution modeling and finally analyses of the modeling results. The study results show that the rift basin structural geometry in the study area is arranged by a series of northward dipping half-grabens with similar polarity in a relatively WNW–ESE general trend, with the average size is about 20 km in length and 10 km in wide. The rift basin evolution in study area can be divided into three main phases: rift initiation, rift climax and immediate post-rift. The modeling results show that each phase of rift evolution has a different facies distribution; the “rift Initiation” was dominated by fluvial conglomeratic-coarse sandstone and sandstone facies. The rift climax is dominated by the lacustrine shale, fine sand and sandy-shale facies. While the immediate post-rift unit is dominated by the fluvio-deltaic conglomeratic-coarse sandstone and sandstone facies. Each facies has an important role to the petroleum system aspects and implication to the hydrocarbon exploration in this area.
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ABSTRAK PEMODELAN DISTRIBUSI FACIES SYNRIFT FORMASI PRE-NGIMBANG DAN NGIMBANG DAN IMPLIKASINYA TERHADAP EKSPLORASI HIDROKARBON DI DAERAH LAUT BALI TIMUR CEKUNGAN JAWA TIMUR-LOMBOK
Yuyus Kusnandar NIM: 22006015 Cekungan Jawa Timur-Lombok merupakan salah satu target eksplorasi yang menjanjikan untuk mencari synrift plays. Tetapi, walaupun seluruh komponen yang diperlukan untuk adanya akumulasi hidrokarbon dapat ditemukan di daerah ini, namun faktanya tingkat keberhasilan eksplorasinya relatif rendah. Studi-studi terdahulu menyebutkan bahwa secara umum sumur-sumur kering di cekungan Jawa Timur-Lombok ini sebagian besar disebabkan oleh masalah migrasi, karena tidak ada atau kurangnya komunikasi antara batuan reservoir dengan batuan sumber di daerah ini. Batupasir endapan synrift dari Formasi Ngimbang dan Pre-Ngimbang dipercayai sebagai lapisan pembawa utama untuk migrasi dan pada beberapa kasus juga berperan sebagai reservoir (misalnya di sumur L46-1 & lapangan Pagerungan). Sementara serpih danau endapan synrift berperan sebagai batuan sumber utama dan sebagian juga berperan sebagai batuan tudung. Oleh karena itu sangatlah penting untuk mengerti penyebaran fasies endapan synrift di daerah ini, guna mengurangi ketidakpastian dalam hal migrasi, perkiraan geometri batuan reservoir serta implikasi umum lainnya terhadap eksplorasi hidrokarbon di daerah ini Penelitian ini dirancang untuk membuat model penyebaran fasies endapan synrift dengan menggunakan teknik pemodelan geo-cellular tiga dimensi yang mengintegrasikan data sumur dan data seismic yang tersedia dengan model konseptual geologi yang baik dari analogi dengan kondisi masa kini. Penelitian ini terbagi dalam lima langkah utama yang meliputi; identifikasi dan rekonstruksi cekungan rift, pembagian unit pengendapan synrift, pengenalan litologi dari data sumur dan seismic, pemodelan penyebaran facies, dan terakhir analisis dari hasil pemodelan tersebut. Hasil penelitian menunjukkan bahwa struktur geometri cekungan rift di daerah penelitian tersusun oleh suatu rangkaian half-grabens berpolaritas sama dengan kemiringan umum ke utara, dan membentuk kelurusan umum pada arah WNW–ESE dengan panjang rata-rata sekitar 20 km dan lebar sekitar 10 km. Evolusi cekungan rift di daerah penelitian dapat dibagi kedalam tiga fase utama; rift initiation, rift climax and immediate post-rift. Hasil pemodelan menunjukkan bahwa tiap fase evolusi cekungan rift memiliki pola penyebaran fasies yang berbeda-beda; tahapan rift initiation didominasi oleh facies batupasir kasar konglomeratan dan batupasir fluvial. Rift climax didominasi oleh fasies serpih danau, pasir halus dan serpih pasiran. Sementara immediate post rift didominasi oleh fasies batupasir kasar konglomeratan dan batupasir fluvio-deltaic. Masingmasing fasies memiliki peranan yang penting bagi aspek sistem petroleum dan implikasi terhadap eksplorasi hidrokarbon di daerah ini.
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THE GUIDANCE OF THESIS UTILIZATION The unpublished master degree (S2) thesis listed and available in library of Institut Teknologi Bandung and open for public with the rule that the copyright is belong to the author and follow the HaKI regulation in Institut Teknologi Bandung. As literature reference allowed being noted, however the citation or summarizing only allowed with permission and should follow the scientific habit to mention the source. Reproducing or publishing a part or the whole thesis should be with the permission from Graduated Program Director of Institut Teknologi Bandung.
PEDOMAN PENGGUNAAN TESIS
Tesis S2 yang tidak dipublikasikan terdaftar dan tersedia di perpustakaan Institut Teknologi Bandung, dan terbuka untuk umum dengan ketentuan bahwa hak cipta ada pada pengarang dengan mengikuti aturan HaKI yang berlaku di Institut Teknologi Bandung. Referensi kepustakaan diperkenankan dicatat, tetapi pengutipan atau peringkasan hanya dapat dilakukan seizin dan harus disertai dengan kebiasaan ilmiah untuk menyebutkan sumbernya. Memperbanyak atau menerbitkan sebagian atau seluruh tesis haruslah seizin Direktur Program Pascasarjana, Institut Teknologi Bandung.
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DEDICATION To my wife, my children, and my parents
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PREFACE Alhamdulillah, all the highest praise to almighty God-Allah SWT, that finally I can accomplish writing this thesis. My special thanks to Dr. Dardji Noeradi and Benyamin Sapiie, Ph.D as my thesis supervisors and to all Lecturers staff of Geological Department of Institut Teknologi Bandung. Many thanks from deepest of my heart to my family, my colleagues, for any help, encouragement, input, and everything. I realized that this thesis is far away from the perfection, however I hope that it could give some contribution, even only a few to scientific and the oil and gas industry in Indonesia. The last but not least I would like to thanks to Eni Indonesia Management for giving me the opportunity to take this graduated program course as well as for the financial and the data support.
Bandung, July 2009 Best regards,
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TABLE OF CONTENTS
APPROVAL SHEET................................................................................... i ABSTRACT .............................................................................................. ii ABSTRAK ................................................................................................ iii THE GUIDANCE OF THESIS UTILIZATION....................................... iv DEDICATION............................................................................................ v PREFACE................................................................................................... vi TABLE OF CONTENTS........................................................................... vii LIST OF FIGURES..................................................................................... ix CHAPTER I. INTRODUCTION................................................................................... I-1 1.1. Background and Problem Statement........................................... I-1 1.2. Research Location....................................................................... I-2 1.3. Research Subject......................................................................... I-2 1.4. Research Data Objects................................................................ I-2 1.5. Research Objectives and Scopes................................................. I-3 1.6. Assumptions................................................................................ I-4 1.7. Hypotheses.................................................................................. I-4 1.8. Research Methodology................................................................ I-4 1.8.1. Data Collecting............................................................. I-5 1.8.2. Data Processing............................................................ I-5 1.8.3. Analysis........................................................................ I-6 1.9. Expected Results and Contributions........................................... I-6
II. REGIONAL GEOLOGY....................................................................... II-1 2.1. Regional Plate Tectonic Setting................................................ II-1 2.2. Basement and Basin Configuration........................................... II-2 2.3. Tectono-stratigraphy of East Java Basin................................... II-6 2.3.1. Pre-Tertiary (Megasequence I).................................... II-6 2.3.2. Paleogene (Megasequence II)...................................... II-7 2.3.3. Neogene (Megasequence III)....................................... II-7
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2.4. Pre-Ngimbang and Ngimbang Formations................................. II-8
III. DATA ANALYSIS AND INTERPRETATION................................... III-1 3.1. Rift Geometry Identification..................................................... III-1 3.2. Rift Evolution Stages and Their Depositional Units Interval Division....................................................................... III-5 3.3. Lithologic Facies Recognition From Well and Seismic Attributes.................................................................................. III-6 3.4. Geocellular Modeling.............................................................. III-8
IV. RESULTS AND DISCUSSION........................................................... IV-1 4.1. Rift Basin Structural Geometry................................................ IV-1 4.2. Lateral Sedimentation Pattern.................................................. IV-3 4.3. Rift Evolution Stages and Vertical Facies Development......... IV-5 4.4. The Synrift Facies Distribution Model of Pre-Ngimbang and Ngimbang Formations.............................................................. IV-8 4.5. The Implication to Hydrocarbon Exploration......................... IV-11
V. CONCLUSSIONS................................................................................... V-1
VI. REFERENCES...................................................................................... VI-1
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LIST OF FIGURES
Figure-1.1: The research area is located in eastern part of Laut Bali area and about 30 km to the north of Lombok Island.................................... I-2 Figure-1.2: The generalized research workflow................................................. I-5 Figure-2.1: The tectonic models of Southeast Asia and Indonesian region...... II-1 Figure-2.2. East Java Basin basement composition (Tognini et al. 2007)........ II-2 Figure-2.3: Tectonic elements of East Java Basin (Sribudiyani et al., 2003)... II-3 Figure-2.4: a. The East Java Basin regional configuration and b. NW-SE cross-section reconstruction from Camar area to Madura Island (Pireno and Mudjiono, 2001)......................................................... II-4 Figure-2.5: The Bali-Lombok sub-basin gravity map (a) and regional crossection (b) (Tognini et al., 2007)................................................................ II-5 Figure-2.6: The East Java basin megasequence chronostratigraphy, lithostratigraphy and petroleum distribution (Bransden & Matthews, 1992)............................................................................................... II-8 Figure-2.7: The seismic reflection geometries of “Pre-Ngimbang/Ngimbang” (After Bransden & Matthews, 1992).............................................. II-9 Figure-3.1:
The
seismic
section
across
halfgraben
units in the Lake
Tanganyika (Line 222) and Malawi (Line 817) Rift Zones (Lambiasse, 1988)......................................................................... III-1 Figure-3.2: The N-S regional line (a) and SW-NE line (b) seismic sections showing a rift geometry in the study area..................................... III-2 Figure-3.3: a. Fault segments trace in study area. b. The cartoon illustrates the classical problems of fault cuts correlation between a set of parallel 2d seismic lines (Freeman et al. 1990).......................................... III-3 Figure-3.4: The plan view and hypothetical cross sections of an ideal
half-
graben and examples of linked half-graben families group (Rosendahl, 1987) ........................................................................ III-4 Figure-3.5: The plan view (a) and 3d view perspective (b) of fault frame work interpretation in study area............................................................ III-4
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Figure-3.6: The rift evolution stages and their distinctive expressions on seismic reflection profiles (Prosser, 1993)................................................. III-5 Figure-3.7:
The seismic reflection profiles of rift depositional unit in study area................................................................................................ III-5
Figure-3.8: The L46-1 well – seismic tie and lithologic-facies reconnaissance in seismic data................................................................................... III-7 Figure-3.9: The amplitude envelope vs lithologic class probability cross-plot and the simplified lithology prediction................................................ III-8 Figure-3.10: The 3D structural geometry modeling parameters........................ III-9 Figure-3.11: The 3D grid cells filled by amplitude envelope values re-sampled along the existing seismic 2D lines…......................................... III-10 Figure-3.12: The geological setting inputs parameter of the object modeling in study area …............................................................................... III-11 Figure-3.13: The variogram analysis results in each syn-rift depositional units…......................................................................................... III-12 Figure-4.1: The map view (a) and W-E direction 3d view perspective (b) of rift basin geometry in study area.............................................. IV-1 Figure-4.2: a) The rift basin tectonic slopes (Leeder & Gawthorpe, 1987) b) The 3d view perspective of tectonic slopes geometry in study area…............................................................................................ IV-2 Figure-4.3: The expected main sedimentation transport system direction and sediment feeder drainage area location in study area................... IV-3 Figure-4.4: The sedimentation pattern in the study area.................................. IV-4 Figure-4.5: The tectono-sedimentary facies model A-Continental extensional basin with interior drainage and facies model B-Continental basin with axial through drainage (Leeder and Gawthorpe, 1987)........ IV-4 Figure-4.6: The facies distribution pattern resulted from the Object Modeling algorithm....................................................................................... IV-5 Figure-4.7: The vertical facies development in each rift evolution stages in study area................................................................................................ IV-6
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Figure-4.8: The generalized block diagram of rift evolution stages; “Rift Initiation”, “Rift Climax” and “Immediate Post-rift” (Prosser, 1993)............................................................................................. IV-7 Figure-4.9:
Idealized section of a half-graben and summary of relationships among tectonic phases, topography in continental rifts (Lambiase, 1988)............................................................................................. IV-8
Figure-4.10: The “Rift Initiation” facies distribution model............................. IV-9 Figure-4.11: The “Rift Climax” facies distribution model.............................. IV-10 Figure-4.12: The “Immediate Post-rift” facies distribution model.................. IV-11 Figure-4.13: Play Types in Southern Basin-Lombok (Pireno, 2004).............. IV-12
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