Ediar Usman
Marine Geological Institute of Indonesia, Jl. DR. Junjunan No. 236, Telp. 022 603 2020, 603 2201, Faksimile 022 601 7887, Bandung

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STUDY OF GAS POTENCY BASED ON GRAVITY ANOMALY MODELING AND SEISMIC PROFILE ANALYSIS AT BANGGAI-SULA BASIN Ediar Usman; Panuju Panuju
BULLETIN OF THE MARINE GEOLOGY Vol 28, No 2 (2013)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (889.951 KB) | DOI: 10.32693/bomg.28.2.2013.55

Abstract

Banggai-Sula Basin is one of the basins with character of the micro-continent derived from northern part of Australia. Some traces the migration in the central part of Papua are slate, schist, and gneiss, current movement is facilitated by the Sorong Fault, which runs from the northern part of Papua to eastern part of Sulawesi. Results of gravity anomaly model (2D and 3D), seepage distribution, seismic and fields existing of oil and gas production in the western part of the Banggai-Sula Basin obtained a new prospect area in the northern part of Peleng Island, western part of Banggai Island, southern part of Banggai-Taliabu Islands, western and eastern part of Sulabesi Island. The new prospect area is reflected in the centre with form of the low morphology on gravity model and prospect trap on seismic data in the western part of Tolo Bay. Results of chemical analysis on the source rock of Buya Formation on Tmax vs Hydrogen Index (Tmax vs HI) Diagram shows the type III kerogen quality and the Oxygen Index vs Hydrogen Index (OI vs HI) Diagram shows the gas prone Type II, so that giving the impression that this area has the potential to containing the gas. The quality of the gas is included in the category of immature to mature type. Key word : marine geology, gravity anomaly model, trap, source rock, hydrocarbon quality, Banggai-Sula Basin Cekungan Banggai-Sula merupakan salah satu cekungan dengan karakter mikro-kontinen yang berasal dari pecahan Australia bagian utara. Beberapa jejak migrasi terdapat di bagian tengah Papua berupa batuan slate, schist, dan gneiss, pergerakannya saat ini difasilitasi oleh Sesar Sorong yang membujur dari Papua bagian utara hingga bagian timur Sulawesi. Hasil pemodelan gaya berat (2D dan 3D), daerah rembesan, seismik dan keberadaan lapangan produksi migas di bagian barat Cekungan Banggai-Sula diperoleh hasil daerah prospek baru di bagian utara P. Peleng, bagian barat P. Banggai, selatan P. Banggai-Taliabu, barat dan timur P. Sulabesi. Daerah prospek tersebut tercermin dari daerah pusat cekungan dengan bentuk morfologi rendahan pada data gaya berat dan prospek perangkap (leads) pada data seismik di bagian barat sekitar Teluk Tolo. Hasil analisis kimia batuan sumber pada Diagram Tmax vs Indeks Hidrogen menunjukkan kualitas kerogen tipe III dan pada Diagram Indeks Oksigen vs Indeks Hidrogen menunjukkan tipe II gas prone, sehingga memberikan gambaran bahwa daerah ini berpotensi mengandung gas. Kualitas gas tersebut termasuk dalam kategori belum matang sampai matang. Kata kunci : geology kelautan, model anomali graviti, perangkap, batuan induk, kualitas hidrokarbon, Cekungan Banggai-Sula
A COMPARISON OF MAJOR ELEMENTS BETWEEN MARINE SEDIMENTS AND IGNEOUS ROCKS: AS A BASIC DETERMINATION OF THE SEDIMENT SOURCE AT UJUNG PENYUSUK WATERS, NORTH BANGKA,BANGKA BELITUNG PROVINCE Ediar Usman
BULLETIN OF THE MARINE GEOLOGY Vol 25, No 1 (2010)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (662.24 KB) | DOI: 10.32693/bomg.25.1.2010.20

Abstract

Three igneous rock samples from the coast and five sediments from the marine of Ujung Penyusuk Waters have been used for chemistry analysis as the basic determination of sediment source. The result of chemistry analysis shows that the major element with relatively same pattern. In the igneous rock samples, the result of chemistry analysis shows the SiO2 ranges between 72.3 - 76.8%, Al2O3 (9.64 - 11.64%), and Fe2O3 ( 2.08 - 2.18%). In the marine sediment, the content of SiO2 is between 62.2 and 66.5%, Al2O3 (2.93 - 3.63%) and Fe2O3 (21.19 - 24.40%). Other elements such as CaO, MgO, K2O, Na2O and TiO2 are relatively similar values in all samples. The difference of element content in marine sediment and coastal igneous rock occurs in Al2O3 and Fe2O3. The Al2O3 is small in marine sediment while the Fe2O3 is higher compared to igneous rocks. Decreasing of the Al2O3 (kaolinite) in the marine sediment is caused by the character of the Al2O3 that was derived from quartz rich of igneous rocks forming kaolinite. It was than deposited in the sea floor. Increasing of the Fe2O3 in marine sediment is caused by addition reaction of the Fe from the sea. Generally, the content of the SiO2 (quartz) in igneous rock and marine sediment belongs to the same group source that is acid igneous rock. The SiO2 in the sediment belongs to a group of granitoid. Keywords: major elements, marine sediment, igneous rock, Ujung Penyusuk waters Tiga contoh batuan dari pantai dan lima contoh sedimen dari dasar laut di perairan Ujung Penyusuk, Bangka Utara telah digunakan untuk analisis kimia sebagai dasar dalam penentuan sumber sedimen. Hasil analisis kimia menunjukkan kandungan unsur utama dengan pola yang relatif sama. Pada contoh batuan beku, hasil analisis kimia memperlihatkan kandungan SiO2 antara 72,3 - 76,8%, Al2O3 (9,64 – 11,64%) dan Fe2O3 (2,08 - 2,18%). Pada sedimen dasar laut memperlihatkan kandungan SiO2 antara 62,2 – 66,5%, Al2O3 (2,93 – 3,63%) dan Fe2O3 (21,19 - 24,40%). Unsur lainnya seperti CaO, MgO, K2O, Na2O dan TiO2 yang relatif sama pada seluruh contoh. Perbedaan kandungan pada sedimen dasar laut dan batuan beku di pantai terjadi pada unsur Al2O3 dan Fe2O3. Kandungan Al2O3 pada sedimen dasar laut lebih kecil dan Fe2O3 lebih besar dibandingkan pada batuan beku. Berkurangnya Al2O3 (kaolin) pada sedimen dasar laut disebabkan oleh sifat Al2O3 yang berasal dari rombakan batuan beku yang kaya kuarsa (SiO2) membentuk kaolin. Unsur tersebut kemudian diendapkan di dasar laut. Peningkatan Fe2O3 pada sedimen dasar laut disebabkan oleh penambahan unsur Fe2O3 yang mengikat unsur Fe dari berbagai mineral di laut. Secara umum, kandungan SiO2 (kuarsa) dalam batuan beku dan sedimen dasar laut termasuk dalam kelompok yang relatif sama yaitu batuan beku asam. SiO2 dalam sedimen termasuk kelompok granitoid. Kata kunci: senyawa utama, sedimen dasar laut, batuan beku, Perairan Ujung Penyusuk.
THE INCLINATION OF COASTLINE CHANGES AND ITS IMPLICATION FOR LANDUSE MANAGEMENT OF KARAWANG DISTRICT, WEST JAWA PROVINCE Ediar Usman
BULLETIN OF THE MARINE GEOLOGY Vol 24, No 1 (2009)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (459.961 KB) | DOI: 10.32693/bomg.24.1.2009.11

Abstract

Result of observation at 11 locations and the coastline analysis at year map 1990 published by Bakosurtanal and year map 2005 published by Bappeda of Karawang District shows that the existence of changes of the coastline is caused by abrasion and accretion process. The coastal abrasions are occurred in Muarabaru, South Pusakajaya, Cemarajaya and Tanjungpakis areas. The coastal accretions are occurred in Ciparage - Sukajaya, Mekarpohaci, Cemarajaya - South Pusakajaya, East and West Tanjungpakis areas. During the periods of 15 years the abrasions are occurred with the width of 813,171 ha (8,13171 km2) and the coastal long of 30,637 km, and accretions with the width of 1346,22 ha (13,4622 km2) and the coastal long of 43,313 km. Every year the width of abrasion is about 54,21 ha or about 0,5421 km2/year and the width of accretion is about 89,748 ha/year or 0,8975 km2/year. The growth of coastal area about 89,748 ha/year or 0,8975 km2/year. If the coastal management is conducted at the abrasion coasts, the coastal damage can be decreased, and the coastal growth for the productive landuse can be increased. Keywords: coastline changes, abrasion, accretion, landuse development. Hasil pengamatan pada 11 lokasi dan analisis garis pantai pada peta tahun 1990 yang dipublikasikan oleh Bakosurtanal dan peta tahun 2005 yang dipublikasikan oleh Bappeda Kabupaten Karawang menunjukkan adanya perubahan garis pantai yang disebabkan oleh proses abrasi dan akresi. Pantai abrasi terjadi di daerah Muarabaru, Pusakajaya Selatan, Cemarajaya, Sedari dan Tanjungpakis. Pantai akresi terjadi di daerah Ciparage - Sukajaya, Mekarpohaci, Cemarajaya - Pusakajaya Selatan dan Tanjungpakis Timur & Barat Selama kurun 15 tahun telah terjadi abrasi seluas 813,171 ha (8,13171 km2) dengan panjang pantai 30,637 km, dan akresi seluas 1346,22 ha (13,4622 km2) dengan panjang pantai 43,313 km. Setiap tahun terjadi abrasi seluas 54,21 ha atau sekitar 0,5421 km2/tahun dan akresi seluas 89,748 ha/tahun atau sekitar 0,8975 km2/tahun. Pertumbuhan kawasan pantai masih lebih besar, yaitu sekitar 89,748 ha/tahun atau sekitar 0,8975 km2/tahun. Bila pengelolaan dilakukan pada pantai-pantai abrasi, maka kerusakan pantai dapat dikurangi dan pertumbuhan pantai untuk lahan produktif masih dapat ditingkatkan. Kata kunci: perubahan garis pantai, abrasi, akresi, pengembangan tataguna lahan.
MORPHOTECTONIC ANALYSIS AT TANIMBAR TRENCH AS A BASE FOR GAS PIPE LAYING BETWEEN MASELA BLOCK AND SELARU ISLAND, MOLUCCAS PROVINCE Ediar Usman; Priatin Hadi Widjaja
BULLETIN OF THE MARINE GEOLOGY Vol 27, No 1 (2012)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2591.237 KB) | DOI: 10.32693/bomg.27.1.2012.43

Abstract

The study area is located at Masela Block and its surrounding, Moluccas Province. Result of the deep sea measurement and global data conversion provide description of three dimensions around the track lines area. This result is overlay with seismic data, that can give morphotectonic implication between Asian and Australian Plates. Track lines of MGI-2010-MSL-1, 2 and 3 show that the profile of the sea floor, form the high morphology which represents the volcanic islands. It forms west – east direction of fold-thrust belt non-volcanic outer Banda arc. The southern part trench of the Australian Continent reflected the platform system and undulation morphology. The sea floor profile ( VE 1:5 ) show that the slope profile ranges between 0º and 8º. Furthermore, the morphology of the sea floor can be classified as a relatively flat slope. Due to this condition, this area may be used for gas pipe laying along 146 km distance, between the Well of Abadi 1 at the Masela Block and Selaru Island at south Tanimbar Islands. Keywords: sea depth, sea floor morphology, seismic profile, tectonic, Masela Block Daerah penelitian terletak di Blok Masela dan sekitarnya, Provinsi Maluku. Hasil pengukuran kedalaman laut dan konversi data global diperoleh gambaran tiga dimensi di sekitar jalur lintasan. Hasil ini kemudian ditumpangtindihkan dengan data seismik, sehingga dapat memberikan gambaran morfologi dan implikasi tektonik antara Lempeng Asia dan Australia. Pada Lintasan MGI-2010-MSL-1, 2 dan 3, menunjukkan profil kedalaman dasar laut membentuk morfologi tinggian yang mewakili pulau-pulau vulkanik. Kondisi ini membentuk suatu jalur punggungan lipatan sesar naik non vulkanik Busur Luar Banda berarah barat – timur. Di bagian selatan palung, mewakili Benua Australia; menunjukkan suatu sistem paparan dan morfologi undulasi Penampang dasar laut (VE 1 : 5) memperlihatkan bahwa kemiringan lereng berkisar antara 0º dan 8º. Selanjutnya morfologi dasar laut ini dapat diklasifikasikan sebagai lereng yang relative landai. Berdasarkan kondisi ini daerah ini kemungkinan dapat digunakan untuk peletakan pipa gas sepanjang 146 km, antara Sumur Abadi 1 di Blok Marsela dan Pulau Selaru di sebelah selatan Pulau Tanimbar. Kata kunci: kedalaman laut, morfologi dasar laut, enampang seismik, tektonik, Blok Masela
IDENTIFICATION OF HARD ROCK BASED ON SHALLOW SEISMIC INTERPRETATION AND SPT TEST FOR FOUNDATION OF BRIDGE AT BALANG ISLAND, BALIKPAPAN BAY, EAST KALIMANTAN Ediar Usman; Kris Budiono
BULLETIN OF THE MARINE GEOLOGY Vol 26, No 1 (2011)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1238.535 KB) | DOI: 10.32693/bomg.26.1.2011.30

Abstract

The study area is located in Balikpapan Bay, the connecting waters between Pancur village at the southwest and Balang Island at the northeast. The objective of study is to know the engineering properties of rock as a foundation groundwork of bridge. Result of seismic reflection interpretation profiles in the survey area indicates that the seismic sequences can be divided into two sequences, those are sequence A and B. Sequence A lies at the upper part, which is characterized by concordance, parallel, wavy and hummocky reflectors. Sequence B is characterized by mounded, chaotic and free reflectors. Sediment thickness obtained from seismic profiles show that Quaternary sediment is about 1.56 to 4.89 meters, while harder substrate thickness ranging between 7.03 and 21.60 meters. While, based on core drilling data, hard rock started to appear between 3 and 4 meters below seafloor with Standard Penetration Test (SPT) between 32 and 34 blows as Tertiary sediments. Based on field observation and correlated with geological map of Balang Island, Balikpapan Sheet, the hard rock proposed for base of bridge foundation is Balang Island Formation (Middle Miocene) that consist of claystone, sandstone and coal layers that have been deformated and start to form fold as anticline. The seismic record show that, the hard rock is interpreted as B sequence that underlain by Quaternary sediments. Key words: seismic, drilling, Quaternary sediment, hard rock, bridge foundation, Balang Island Daerah penelitian terletak di Teluk Balikpapan, merupakan perairan penghubung antara desa Pancur di bagian baratdaya dan Pulau Balang di bagian timurlaut. Tujuan penelitian in untuk mengetahui sifat keteknikan batuan keras sebagai tapak jembatan. Hasil interpretasi rekaman seismik di lokasi penelitian menunjukkan bahwa sekuen sedimen dapat dibagi menjadi dua yaitu Sekuen A dan B. Sekuen A terletak di bagian atas dengan ciri reflektor selaras, sejajar, bergelombang terputus-putus dan perlapisan terputus-putus. Bagian paling bawah adalah Sekuen B dicirikan oleh bentuk reflektor berbukit-bukit kecil, berbintik-bintik kacau tidak beraturan dan makin ke bawah dicirikan oleh bebas pantul. Hasil perhitungan ketebalan sedimen pada penampang seismik diperoleh ketebalan sedimen Kuarter antara 1,56 - 4,89 meter dan kedalaman batuan keras berkisar antara 7,03 – 21,60 meter. Sedangkan berdasarkan data pemboran, batuan keras mulai muncul pada kedalaman 3 - 4 meter di bawah dasar laut dengan SPT antara 32 – 34 sebagai sedimen Tersier. Berdasarkan pengamatan di lapangan dan dikorelasikan dengan peta geologi P. Balang, Lembar Balikpapan, batuan keras yang diusulkan sebagai dasar tapak jembatan adalah Formasi Pulau Balang (Miosen Tengah) yang terdiri atas batulempung, batupasir and batubara yang sudah mengalami deformasi dan mulai terlipat membentuk antiklin. Pada penampang seismik, batuan keras tersebut adalah Sekuen B yang ditutupi oleh sedimen Kuarter. Kata kunci: seismik, pemboran, sedimen Kuarter, batuan keras, tapak jembatan, Pulau Balang.