Sedimentology of the ngrayong formation and its sandstone reservoir characterization

SEDIMENTOLOGY OF THE NGRAYONG FORMATION AND ITS SANDSTONE RESERVOIR CHARACTERIZATION Along Braholo River, Ngampel Village, Blora District Central Java Province, Indonesia By NGUYEN THI BICH NGOC 20639/I-1/2062/03 Thesis submitted for the Degree of Master of Engineering Department of Geological Engineering Faculty of Engineering POST GRADUATE PROGRAM GADJAH MADA UNIVERSITY YOGYAKARTA 2005 i ii I have the honor of giving my deep gratitude to my parents for their kindness and love The basic principle of spiritual life is that our problems become the very place to discover wisdom and love Jack Kornfield iii ABSTRACT The Ngrayong Formation has been studied for a long time However, depositional environment of Ngrayong Formation has been determined differently from various author Therefore, Ngrayong Formation was attracted to study deeper about its depositional environment The measure section was carried out along Braholo River from Ngampel to Sendangharjo village for vertical profile lithologic column According to stratigraphic sequence of Rembang zone, the Ngrayong Formation conformably overlies the Tawun Formation Meanwhile, the Bulu Formation unconformably overlies the Ngrayong Formation Depositional environment was studied in term of sedimentology of Ngrayong Formation and its sandstone reservoir characterization Sedimentology emphasized on foraminifera, trace fossil, grain size analysis, petrography analysis (thin section), provenance Porosity and permeability of the sandstone of Ngrayong Formation were also measured to evaluate reservoir quality Porosity and permeability were measured by consolidation permeameter The grain size analysis showed that the sandstone is fine to medium grain (2.03 3.14 phi), moderately well-sorted to well-sorted (with standard deviation range from 0.36 to 1.0 phi), subrounded to rounded, supermature sediments, whereas, the sandy claystone is characterized as poorly sorted (with standard deviation range from 1.09 to 1.75 phi), and immature sediments The depositional environment of sandstones could be sand bar environment and lagoon environment for sandy claystones With QFL ternary plot, the provenance of sandstone of Ngrayong Formation came from continental blocks Moreover, the composition of sandstone and heavy mineral (apatite, rutile, kyanite, zircon, hematite, magmatite, and tourmaline) reflected the sediments of Ngrayong Formation came from plutonic igneous rock and metamorphic rock origin Porosities range from 31 percents to 44 percents Permeabilities range from 61 milidarcies to 372 milidarcies These porosities and permeabilities are very good to consider the sandstones of Ngrayong Formation as reservoir rocks However, permeabilities were higher than 1500 milidarcies by grain-size analysis method Results of the study show that relative sea level changes have affected the processes and products of sedimentation in the Northeast Java Basin during the Middle Miocene The Ngrayong Formation is composed of six cycles Each cycle consists of a series of sandy limestone - quartz sandstone - sandy claystone or shale layers Base on foraminifera fossils (Amphistegina lessonii, Elphidium sp, Quinqueculina sp, Asterorotalia gaimadii, Lepidocyclina sp, Cyclocypues sp) and trace fossils (Thalassinoides), the depositional environment of Ngrayong Formation is in inner shelf to middle shelf environment Moreover, the lithologies and sedimentary textures of the Ngrayong Formation points to deposit on a transitional environment as indicated by presence of quartz sandstone and limestone beds, and sandy claystone or shale respectively, particularly in sand bar environment and in lagoonal environment The sea level change has also been ascertained during the depositional processes of Ngrayong Formation There were upward deepening up to the middle sequence section and shallowing again upward to the top of the sequence The age of Ngrayong Formation is Middle Miocene (N7-N9) The conclusive proofs were shown in this thesis Key words: Depositional environment, paleontology, petrography, grain size analysis, heavy mineral, provenance, reservoir quality of sandstone, Ngrayong Formation iv INTISARI Formasi Ngrayong telah dipelajari sejak lama Meskipun demikian, lingkungan pengendapan Formasi Ngrayong selah di determinasi secara berbeda dari satu peneliti ke peneliti lainnya Oleh karenanya, Formasi Ngrayong menjadi menarik untuk dipelajari lebih dalam sentang lingkungan pengendapannya Pengulunan stratigrafi telah dikerjakan sepanjang sungai Braholo, dari desa Ngampel hingga desa Sendangharjo untuk mendapatkan kalom litologi penampang vertical Berdasarkan sekuen stratigrafi zona Rembang, Formasi Ngrayong terletak selaras distas Formasi Tawun, sedangkan Formasi Bulu memumpang tidak selaras diatas Formasi Ngrayong Lingkungan pengendapan Formasi Ngrayong serta karakterisasi reservoar batu pasiunnya dipelajari dari segi sedimentologi Sedimentologi menekankan pada foraminifera, fosil jejak, analisis ukuran butir, analisi pertrografi (sayatan tipis), serta provenan Porositas dan permeabilitas batupasir Formasi Ngrayong juga diukur untuk evaluasi kualitas reservoar Porositas dan permeabilitas diukur dengan alat “consolidation permeameter” Analisis ukuran butir menunjukan karakterisasi batupasir yaitu halus sampai menengah (2.03 - 3.14 phi), sortasi cukup baik hingga baik (dengan simpangan baku berhiasan dari 0.36 sampai 1.0 phi), membulat tanggung hingga membulat, merupakan sedimen super-mature dan batulemgpung pasiran mencirikan sortasi buruk (dengan simpangan baku berhiasan dari 1.09 sampai 1.75 phi), merupakan sedimen immature Lingkungan pengedapan batupasir menandakan lingkungan sand-bar, dan batulempung pasiran mencirikan lingkungan lagoon Dengan cara ploting diagram QFL, provenan batupasiran Formasi Ngrayong berasal dari blok kontinental Selain itu, komposisi batupasir dan mineral berat (apatit, rutil, kyamit, zirkon, hematit, magnetit, dan turmalin) mencerminkan endapan Formasi Ngrayong berasal dari batuan beku plutonik dan batuan metamorf Porositas berhiasan dari 31 persen sampai 44 persen Pemeabilitas berhiasan dari 61 milidarey sampai 372 milidarey Porositas dan permeabilitas ini sangat baik dan memungkinkan batuopasir Formasi Ngrayong menjadi batuan reservoar Akan tetapi, permeabilitas lebih tinggi dari 1500 milidarey berdasarkan hasil analisis ukuran butir Hasil studi ini menunjukkan bahwa perubahan muka air laut relatif telah mempengaruhi proses dan produk sedimentasi di Cekungan Jawa Timurlaut selama kala Miosen Tengah Pengendapan Formasi Ngrayong terdiri dari enam siklus Setiap siklus terdiri dari suatu deret lapisan-lapisan batugamping pasiran – batupasir kuarsa – batulempung pasiran atau serpih Fosil Foraminifena ( Amphistegina lessonii, Elphidium sp, Quinqueculina sp, Asterorotalia gaimadii, Lepidocyclina sp, Cyclocypues sp) dan fosil jejak (Thalassinoides) menunjukkan bahwa lingkungan pengendapan tepian tengah (middle shelf) hingga tepian dalam (inner shelf) Umur Formasi Ngrayong yaitu Miosen Tengah Litologi, fosil dan tekstur pengendapan mencirikan bahwa Formasi Ngrayong terbentuk pada lingkungan transisi Khususnya pada lapisan batupasir kuarsa dan batugamping diendapkan pada lingkungan sand-bar, serta batulempung pasiran dan serpih diendapkan pada lingkungan lagoon Akan tetapi, maka air laut mengalami perubahan selama proses pengendapan Formasi Ngrayong Kenam memingirkan telah terjadi pendalaman ke arah atas hingga penampang sekuen tengah dan pendangkalan kembali ke arah atas hingga puncak dari sekuen Kesimpulan itu ditunjukkan dalam tesis ini Kata kunci: Lingkungan pengendapan, paleontologi, petrografi, analisis ukuran butir, provenan, kualitas reservoar batupasir, Formasi Ngrayong v ACKNOWLEDGEMENT I would like to thank JICA and AUN/SEED-Net Secretariat at Bangkok which provided me the scholarship; to Gadjah Mada University at Yogyakarta, especially the Geological Engineering Department, that accepted me to study Master degree; and to the Ho Chi Minh City University of Technology that supported my study in Indonesia I want to express my gratefulness and esteem to Dr Subagyo Pramumijoyo (my advisor at the Gadjah Mada University, Indonesia) and Prof Dr Koichiro Watanabe (Co-advisor at Kyushu University, Japan), who guided and criticized me during my thesis preparation and writing I would like to show my gratitude to lecturers who taught me in two first semesters and lecturers who did not teach me but nevertheless gave me their helpful advice during the completion of my thesis Lecturers (Wartono Rahardjo, Budianto Toha, MSc, Bambang Budiyono in Paleontology Laboratory; Widiasmoro, MT, Dr I Wayan Warmada in Mineral Resources Laboratory; Agus Hendratno, ST, MT, in Optical Laboratory; Jarot Setyowiyoto MSc., in Sedimentography Laboratory), assistants, and students (Akmaluddin, ST, Moch Indra Novian, ST, Didit Hadi Barianto, ST, Gayatri Indah Meilani, Fathoni Mukti Raharjo in Paleontology Laboratory; Wanni, ST, Fenny Thamba, ST, Prakasa Ardiyanto in Mineral Resources Laboratory; Yuslan, Sarju Winardi, ST, in Sedimentography Laboratory), are thanked for all their help in laboratory works Mr Mamat (Directorate Geology and Mineral Resources, Bandung) and Dipl.-Ing Andri S Mubandi (Geological Engineering Department, Institute of Technology Bandung), who prepared thin section and gave their experiences enthusiastically in thin section analysis, are also thanked I would like to express heartfelt thanks to Ir H Moch Yohannes PK, M.Sc, (Departmen Energi dan Sumber Daya Mineral, Pusat Pendidikan dan vi Pelatihan Minyak dan Gas Bumi, Cepu) who accompanied me on field works and supported significant references I have the honor of giving my deep gratitude to my parents for their kindness and love They always give me words of encouragement in whatever I Finally, thanks to all my Vietnamese friends and colleagues who helped me out during difficulty times in my study in Indonesia I am glad to receive your warm suggestions to complete a good research or enhance my knowledge Thank you for all your kind attention Ms Nguyen Thi Bich Ngoc vii TABLE OF CONTENTS Title page i Approval sheet ii Abstract iv Acknowledgement vi Table of contents viii List of figures x List of tables xiii Chapter I INTRODUCTION I.1 Background I.1.1 The study location I.1.2 Scope of study I.1.3 The purposes of study I.2 Research methodology I.2.1 Paleontology analysis I.2.1.1 Outcrops selection I.2.1.2 Sampling methods I.2.1.3 Sample preparation I.2.1.4 Standard criteria I.2.2 Granulometry analysis I.2.3 Petrography I.2.4 Consolidation permeameter 11 I.2.5 Heavy minerals determination 12 Chapter II GEOLOGY 14 II.1 Regional geology of NE Java Basin 14 II.2 Tertiary stratigraphy of Cepu-Blora area 18 II.3 The Ngrayong Formation along Braholo River 24 Chapter III PALEONTOLOGICAL AND SEDIMENTOLOGICAL DATA ANALYSIS 31 III.1 PALEONTOLOGY 31 III.1.1 Foraminifera 33 III.1.1.1 Factors of living foraminiferal distributions 33 IV.1.1.2 Sedimentary environment 36 III.1.1.2.1 Benthonic foraminifera 36 III.1.1.2.2 Planktonic foraminifera 39 III.1.1.2.3 Large foraminifera 39 III.1.2 Trace fossil 42 III.2 SEDIMENTOLOGY 46 III.2.1 Grain size analysis 46 III.2.1.1 Grain size data analysis 46 III.2.1.1.1 Histograms 47 viii III.2.1.1.2 Cumulative curves 47 III.2.1.1.3 Graphical treatment of grain size data 47 III.2.1.2 Interpretation 49 III.2.1.2.1 Grain size 49 III.2.1.2.2 Sorting 50 III.2.1.2.3 Roundness 53 III.2.1.1.4.4 Textural maturity 54 III.2.2 Provenance of sandstone in Ngrayong Formation 56 III.2.2.1 Description of mineralogical composition 59 III.2.2.2 Sandstone Provenance 64 III.2.2.2.1 Petrographic Analysis 64 III.2.2.2.2 Heavy Minerals analysis 67 III.2.2.3 Interpretation and discussion 72 III.3 RESERVOIR QUALITY 76 III.3.1 Influence of depositional environment on reservoir quality prediction 76 III.3.1.1 Influences of Composition 78 III.3.1.2 Influences of Texture 79 III.3.2 Porosity and permeability value 80 Chapter IV DISCUSSION, CONCLUSION AND RECOMMENDATION 84 IV.1 Discussion 84 IV.1.1 Paleontology 84 IV.1.2 Sedimentology 86 IV.1.3 Reservoir quality 88 IV.2 Conclusion 90 V.3 Recommendation 91 REFERENCE 92 Appendix A Histogram curves plotted from grain size analysis of Ngrayong Formation 99 Appendix B Cumulative curves with an arithmetic ordinate scale plotted from grain size analysis of Ngrayong Formation 106 Appendix C Results of heavy mineral analysis 113 Appendix D Results of paleontological analysis 120 Appendix E Definition of used terms in thesis research 125 ix LIST OF FIGURES Chapter I Introduction Figure I 1: Location map of study area Figure I 2: Research scheme of thesis study Figure I 3: Terminology and class intervals for grade scales Figure I 4: Relation between framework composition of sandstones and tectonic setting 10 Figure I 5: A constant head permeameter is a device for measuring the permeability of a coarse grained soil 11 Chapter II Geology Figure II 1: Regional plate tectonic setting of SE Asia The area of East Java is highlighted by a red box 15 Figure II 2: Geological cross section of the East Java, showing the Ngrayong Formation – Depositional Model 17 Figure II 3: The stratigraphic column of North East Java Basin 19 Figure II 4: Location map of study area showing sampling points within Ngrayong Formation 20 Figure II 5: The sharp contact between Ngrayong Formation and Bulu Formation, picture to the south, Braholo River, Sendangharjo Village 24 Figure II 6: The sharp contact between Ngrayong Formation and Bulu Formation, picture to the west Braholo River, Sendangharjo Village 24 Figure II 7: The contact between Ngrayong Formation and Tawun Formation, Braholo River, Ngampel Village 25 Figure II 8: The contact between Ngrayong Formation and Tawun Formation, Braholo River, Ngampel Village 25 Figure II 9: Limestone intercalation with sandstone, bedding direction N1000E/300S, first cycle, Braholo River, Ngampel Village 27 Figure II 10: Cross bedding was found in sandstone (on lap), bedding direction N1000E/320S First cycle, Braholo River, Ngampel Village 27 Figure II 11: Sandstone and thin limestone facies , direction N1000E/320S third cycle, Ngampel Village 28 Figure II 12: The nodule grain of limestone, fourth cycle, Ngample Village 28 Figure II 13: Ripple marks were found in claystone at Ngampel Quarry 29 Figure II 14: Burrow traces were found in sandy claystone at Ngampel Quarry 29 Figure II 15: Laminated claystone, sixth cycle, Braholo River, Sendangharjo Village 30 Chapter III Paleontological and sedimentological data analysis Figure III 1: The benthonic foraminifera (1-15) and planktonic foraminifera (1619) were found in Ngrayong Formation 35 x Appendix B cumulat ive weight percent Cumulative curve SE - 1G 100 90 80 70 60 50 40 30 20 10 -1 4.25 pan Phi value cumulat ive weight percent Cumulative curve SE - 1C 100 90 80 70 60 50 40 30 20 10 -1 4.25 pan Phi value 111 Appendix B cumulat ive weight percent Cumulative curve BR1 - 4B 100 90 80 70 60 50 40 30 20 10 -1 4.25 pan Phi value cumulat ive weight percent Cumulative curve BR1 - 1C 100 90 80 70 60 50 40 30 20 10 -1 4.25 pan Phi value 112 Appendix C APPENDIX C Results of Heavy Mineral Analysis (Note: the percentage of total heavy mineral were considered as 100 % from less than 1% heavy mineral of rock sample) No sample Mineral BR2-3A Obs Obs Obs Obs Obs Obs Obs Total Hematite 5 4 30 25.42 Zircon 2 2 18 15.25 Rutile 6 46 38.98 Kyanite 4 3 3 24 20.34 Total 20 17 17 14 16 17 17 118 100.00 No sample Mineral Percentage BR1-1C Obs Obs Obs Obs Obs Obs Obs Total Percentage Magnetite 8 49 24.50 Hematite 13 14 12 13 14 14 12 92 46.00 Apatite 3 3 20 10.00 Zircon 2 2 3 16 8.00 Kyanite 4 3 23 11.50 Total 27 30 27 28 31 31 26 200 100.00 113 Appendix C No sample Mineral BR2-2B Obs Obs Obs Obs Obs Obs Total Percentage Pyrite 11 23 25 19 21 18 117 52.47 Hematite 14 11 11 10 63 28.25 Zircon 1 1 11 4.93 Apatite 2 3.14 Rutile 15 6.73 Kyanite 1 10 4.48 Total 30 47 44 37 34 31 223 100.00 No sample BR2-5A Mineral Obs Obs Obs Obs Obs Total Percentage Magnetite 7 31 30.69 Kyanite 11 9 11 48 47.52 Zircon 4 22 21.78 Total 21 19 19 20 22 101 100.00 114 Appendix C No sample Mineral Obs SE-1C Obs Obs Obs Obs Obs Total Percentage Rutile 11 11 44 31.43 Tourmaline 3 20 14.29 Hematite 1 5.00 Zircon 4 23 16.43 Apatite 9 46 32.86 Total 24 18 25 19 28 26 140 100.00 Obs Obs Obs Obs Total Percentage No sample Mineral Obs BR2-3B Obs Apatite 11 11 53 42.40 Rutile 2 4 17 13.60 Zircon 11 8 49 39.20 Hematite 1 4.80 Total 19 23 24 19 21 19 125 100.00 115 Appendix C No sample Mineral BR2-5B Obs Obs Obs Obs Obs Obs Obs Total Percentage Garnet 4 4 26 16.15 Kyanite 2 18 11.18 Zircon 11 14 17 12 11 11 82 50.93 Rutile 4 30 18.63 Hematite 1 1 3.11 Total 24 24 25 21 22 17 28 161 No sample Mineral Obs NG-1B Obs 100.00 Obs Obs Obs Obs Total Percentage Rutile 6 31 15.42 Hematite 13 16 18 16 18 16 97 48.26 Zircon 4 3 23 11.44 Apatite 2 16 7.96 Kyanite 7 34 16.92 Total 29 34 38 34 34 32 201 100.00 116 Appendix C No sample Mineral Obs SE-1G Obs Obs Obs Obs Obs Total Percentage Magnetite 1 1 13.04 Apatite 8 6 40 86.96 Total 9 46 100.00 No sample Mineral Obs BR1-4B Obs Obs Obs Obs Total Percentage Magnetite 21 22 21 19 17 100 44.84 Zircon 9 40 17.94 Tourmaline 37 16.59 Rutile 28 12.56 Pyrite 4 18 8.07 Total 44 47 51 44 37 223 100.00 117 Appendix C No sample Mineral BR2-4B Obs Obs Obs Obs Obs Obs Obs Total Percentage Pyrite 12 11 11 12 71 42.51 Magnetite 8 49 29.34 Tourmaline 2 3 18 10.78 Zircon 4 4 5 29 17.37 Total 19 26 24 23 21 27 27 167 100.00 No sample Mineral NG-1C Obs Obs Obs Obs Obs Obs Obs Total Percentage Zircon 2 4 20 21.98 Hematite 4 4 25 27.47 Rutile 4 4 23 25.27 Tourmaline 3 4 23 25.27 Total 10 12 13 15 14 13 14 91 100.00 118 Appendix C No sample Md-1A Mineral Obs Obs Obs Obs Obs Obs Obs Obs Total Percentage Apatite 12 11 70 35.18 Garnet 4 4 28 14.07 Rutile 4 4 4 29 14.57 Turmaline 4 22 11.06 Zircon 3 3 20 10.05 Magnetite 4 4 30 15.08 Total 20 20 28 26 28 27 26 24 199 100.00 119 Appendix D Appendix D Results of paleontological analysis GADJAH MADA UNIVERSITY AREA NGAM PEL VILLAGE LABORATORY OF PALEONTOLOGY SECTION NBR Cycle FOSSIL GROUP TREATED: ABUNDANCE PRESERVATION Barren Rare Poor Few Common Abundant Moderate Thin section Sieve SPECIES DATE OBSERVER STAGE/ZONE: PALEOBATHYMETRY: Transitional – inner shelf Other ZONATION Abundance Amphistergina aucklandica 10 REMARKS: REGISTERED NBR SAMPLE NBR BR2-5A Good SAMPLE PREPARATION PROCEDURE Smear SECTION NGRAYONG FORMATION Non Transitional marine Inner Mid Outer Shelf Upper Lower Slope PALEOBATHYMETRY 120 Abyssal Appendix D GADJAH MADA UNIVERSITY AREA NGAM PEL VILLAGE LABORATORY OF PALEONTOLOGY SECTION NBR Cycle FOSSIL GROUP TREATED: ABUNDANCE PRESERVATION Barren Rare Poor Few Common Abundant Moderate Thin section OBSERVER PALEOBATHYMETRY: N7 –N8 Inner shelf Other Abundance Globigerinoides bisphericus >10 Globigerinoides altiaperta 6-10 Globoquadrina dehiscens 10 Globoquadrina dehiscens >10 Globorotalia continuosa 6-10 Amphistergina lessonii >10 Asterorotalia concinna >10 Operculina sp >10 Quinqueculina padana Quinqueculina poeyana >10 Lenticulina rotulata 10 Elphidium aff jensem >10 Elphidium clavatum >10 Quinqueculina aknemna