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Jurnal Geofisika Eksplorasi
Published by Universitas Lampung
ISSN : 23561599     EISSN : -     DOI : -
Core Subject : Science,
Jurnal Geofisika Eksplorasi adalah jurnal yang diterbitkan oleh Jurusan Teknik Geofisika Fakultas Teknik Universitas Lampung. Jurnal ini diperuntukkan sebagai sarana untuk publikasi hasil penelitian, artikel review dari peneliti-peneliti di bidang Geofisika secara luas mulai dari topik-topik teoritik dan fundamental sampai dengan topik-topik terapandi berbagai bidang. Jurnal ini terbit tiga kali dalam setahun (Maret, Juli dan November), Volume pertama terbit pada tahun 2013 dengan nama Jurnal Geofisika Eksplorasi (JGE).
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Articles 71 Documents
PENENTUAN KELAS ANOMALI AVO PADA RESERVOAR BATUPASIR LAPANGAN ILM FORMASI GUMAI-D SUB CEKUNGAN JAMBI Yuliansyah, Zaivan
Jurnal Geofisika Eksplorasi Vol 2, No 01 (2014)
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Abstract

AVO analysis methods have been widely done by researchers to be able to determine the class of gas reservoir anomaly. Pick AVO application and crossplot analysis between AVO Attribute, there are Intercept and Gradient can prove to determination of anomaly gas sandstone class at ILM Field Gumai-D Formation Jambi Sub-Basin. Class I gas sandstone anomaly in Vanda-1 and Vanda-3 wells area, and Class III gas sandstone anomaly in Vanda-2 well area. Keywords: AVO, Intercept, Gradient.
STUDI PENCITRAAN STRUKTUR BAWAH PERMUKAAN BUMI MENGGUNAKAN PEMODELAN CONSTRAINED VELOCITY INVERSION DAN GRID BASED TOMOGRAPHY PADA LINTASAN GMR165 DI DAERAH TELUK CENDRAWASIH Rizka, Gamal Muhammad
Jurnal Geofisika Eksplorasi Vol 1, No 02 (2013)
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Abstract

  Prestack Depth Migration (PSDM) method has been applied to image the subsurface at Line GMR165 in Cendrawasih Bay. Imaging   and   positioning   is   the  most  important   issue   in seismic   data   processing.   In   the complex area case with lateral variation velocity , PSDM has more benefit than PSTM . It cause  the   ability   of   PSDM   method   that   can   focus just   for  one   reflector   when lateral velocity change.  In this study used constrained velocity inversion modelling method. This method is designed to make an initial interval velocity model for PSDM and updated in grid based tomography to got the best velocity so that the result had  continuous PSDM reflector with flat gather. That interval velocity applied to PSDM to get seismic image section and compared with PSTM (prestack time migration) seismic section based on it’s image and velocity model analysis. Seismic section of PSDM shows a significant image enhancement. It is able to assure the reflection pattern at the horizons with strong lateral velocity variations and makes image resolution more coherence than seismic section of PSTM. This study is very valuable to build exploration concept and development area, especially in a complex structure with strong lateral velocity variations.Keywords: Pre Stack Depth Migration, Constarined Velocity Inversion, Grid Based Tomography.  
KARAKTERISASI RESERVOAR HIDROKARBON PADA LAPANGAN “TAB” DENGAN MENGGUNAKAN PEMODELAN INVERSI IMPEDANSI AKUSTIK Simanjuntak, Adi Sutanto
Jurnal Geofisika Eksplorasi Vol 2, No 01 (2014)
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Abstract

Research has been performed with the characterization of hydrocarbon reservoir in “TAB” field using acoustic impedance inversion modeling. Acoustic impedance (AI) is a rocks ability to parse seismic waves that is the product results from rock density and velocity. Acoustic impedance also influenced by the type of litology, pressure, temperature, porosity and fluid content. This research used AI inversion method because a result of this inversion can give a imaging of the actual subsurface conditions, so that it can mapping the distribution of porosity reservoir target. The purpose of this research is determine value of acoustic impedance inversion results in the reservoir, estimate value of porosity a rocks in the reservoir and mapping the pattern of spread reservoir through analysis of acoustic impedance and porosity values. with comparing the results of inversion from some inversion modeling such as Bandlimited, Model Based and Linear Programming Sparse-Spike, so used is linear programming sparse spike model. The result of linear programming sparse spike model showing good correlation is 0.927 and the small error is 0.440 and does not depend on initial model, so it is good to used for targets that have a high reflectivity value. The results of inversion showing acoustic impedance located in low impedance zone between 2000 m/s*gr/cc - 3458 m/s*g/cc with depth around 1500 to 1700 ms. From this results has been slicing of the data. This slicing data is done with a window on 10 ms under the horizon, 20 ms under the horizon, and 30 ms under the horizon. Distribution of porosity inversion results is done by using 7 attribute. The results of porosity distribution obtained an average of 30%. Slicing porosity that shows the acoustic impedance values located in low anomaly which have a high porosity.Keyword: Acoustic Impedance (AI), Linear Programming Sparse Spike (LPSS), porosity
KARAKTERISASI RESERVOAR "FEBRI-UNILA FIELD" MENGGUNAKAN METODE ACOUSTIC IMPEDANCE (AI) INVERSION Kartika, Febrina
Jurnal Geofisika Eksplorasi Vol 1, No 01 (2013)
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Abstract

AI  (Acoustic Impedance)  adalah salah satu parameter  fisis  batuan yang nilainya dipengaruhi oleh tipe litologi, porositas, kandungan fluida, kedalaman tekanan dan temperatur.  Oleh karena itu  AI  (Acoustic Impedance)    digunakan sebagai indikator porositas, pemetaan litologi, dan menentukan karakteristik reservoar pada Febri-Unila Field.  Secara umum inversi  AI  (Acoustic Impedance)    akan memberikan gambaran geologi bawah permukaan  yang lebih detail dari pada seismik  konvensional. Karena umumnya amplitude pada seismik  konvensional  hanya menggambarkan batas lapisan batuan, sedangkan AI  (Acoustic Impedance)     memberi gambaran  karakteristik batuan itu sendiri. Karakterisasi “Febri-Unila Field” menggunakan data seismik 3D, horizon, dan data sumur sebagai data input.   Pada reservoar  target  (channel-infill),  Acoustic Impedance  (AI)  Inversion  akan memetakan distribusi lateral Acoustic Impedance  (AI) dengan menggunakan teknik   Linier  Programing Sparse Spike  (LPSS) Inversion, kemudian sebaran  Acoustic Impedance  (AI)  hasil inversi  dikonversikan ke porositas dengan menggunakan multiatributte. Metode  Linier Programing Sparse Spike (LPSS) Inversion  dipilih  sebagai fokus teknik inversi,  karena  tidak terlalu bergantung pada initial model, dan metode  Linier Programing Sparse  Spike (LPSS)  Inversion  cocok diterapkan pada data yang memiliki reflektivitas baik.  Hasil  inversi menunjukkan  sebaran  channel  ditemukan mulai dari   time  1050 ms,  berada pada anomali Acoustic Impedance  (AI)  rendah, dengan nilai antara 21042 ft/s*gr/cc  -31468  ft/s*gr/cc dengan ketebalan  channel  yang bervariasi, hingga mencapai 35 m. Konversi porositas menggunakan  7 attribute, menunjukan zona  low impedance memilki porositas tinggi hingga sekitar 18 %.
ANALISIS KARAKTERISTIK DAN KLASIFIKASI GEMPA PADA GUNUNG LOKON BERDASARKAN REKAMAN DATA SEISMOGRAM APRIL – MEI 2012 Putri, Leovina Prinanda
Jurnal Geofisika Eksplorasi Vol 1, No 02 (2013)
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This research has been carried out aiming to classify earthquakes at Lokon Volcano and analyze the character of the earthquakes to determine the mechanism of the eruption of Lokon Volcano is based on the data recorded seismograms April to May 2012. The stages in analyzing the characteristics of the earthquake is the waveform analysis and spectral analysis . On waveform analysis aims to determine the P wave comes time ( Tp ) and S waves ( Ts ) and the duration of the earthquake . While spectral analysis aimed to determine the frequency of these earthquakes . The second stage of the obtained classification of volcanic earthquakes in the earthquakes, shallow volcanic earthquakes, earthquake monochromatic, and tectonic earthquake. Shallow volcanic earthquakes located at depths of 0.5 to -1.5 km , duration range from 3 to 16 seconds with a frequency range from 4 Hz to 18 Hz . Volcanic earthquakes located at depths -6 km to -1,duration range from 6 to 20 seconds with a frequency range from 6 Hz to 13 Hz . Earthquake discovered long period is two monochromatic low frequency earthquakes at depths of up to -1.5 -2 km which has two peaks in each of the station frequency is the frequency of the dominant and sub - dominant . Dominant frequency of the seismic monochromatic range 2.88 Hz to 4.88 Hz and sub -dominant frequency range from 5.04 Hz to 8.7 Hz . Duration of tectonic earthquakes about 50 until 470 seconds with a frequency range from 1 to 6 Hz. Volcanic earthquakes and monochromatic associated with normal faulting .Increased seismic activity indicates impending eruption.Keywords : hypocenter , classification earthquake , monochromatic earthquake , eruption mechanisms.
STUDI IDENTIFIKASI STRUKTUR BAWAH PERMUKAAN DAN KEBERADAAN HIDROKARBON BERDASARKAN DATA ANOMALI GAYA BERAT PADA DAERAH CEKUNGAN KALIMANTAN TENGAH Erviantari, Dian
Jurnal Geofisika Eksplorasi Vol 2, No 01 (2014)
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In this study, it has been to identified the structural and hidrocarbon prospect on Central Kalimantan Basin using gravity method. Fault Structure in this Field  has been identified using second vertical derivative and 3D inversion modelling Bouguer Anomaly. Bouguer anomaly in this field has a high anomaly in the center while the low anomaly in the north and south area. From second vertical derivative anomaly map indicated presence normal fault on NE-SW direction. Hidrocarbon prospect in this area are corelate with high residual anomaly.Keywords       : Bouguer Anomaly, Fault, Second Vertical Derivative, Structure
KARAKTERISASI RESERVOAR FORMASI BELUMAI DENGAN MENGGUNAKAN METODE INVERSI IMPENDANSI AKUSTIK DAN NEURAL NETWORK PADA LAPANGAN ‘YPS’ Kurniawan, Andri
Jurnal Geofisika Eksplorasi Vol 1, No 01 (2013)
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Penelitian ini bertujuan untuk mengetahui struktur layer Formasi Belumai, menganalisis nilai sebaran  impedansi akustik dan porositas reservoar yang diperoleh dari proses inversi seismik dan neural network, untuk menentukan zona lokasi sumur baru berdasarkan peta struktur waktu, atribut seismik, dan sebaran porositas. Data seismik yang digunakan merupakan data seismik non preserve 2D PSTM, data sumur YPS-04 dan YPS-06 yang memiliki kelengkapan data log (checkshot, sonic, density, dan porosity). Trasing horizon menunjukkan dua bagian tutupan (antiklin) pada arah  timur dan barat mengarah ke NW-SE. Dari hasil penelitian dengan menggunakan metode inversi modelbased dan analisa atribut RMS amplitude, instantaneous frequency, envelope dan neural network menunjukkan sebaran porositas di layer TBF (Top Belumai Formation) memiliki nilai porositas 0,12-0,21 fraksi dengan nilai impedansi 8000-12000 (m/s)*(gr/cc). Pada layer BBF (Bottom Belumai Formation) memiliki nilai porositas 0,09-0,21 fraksi dengan nilai impedansi 7000-12000 (m/s)*(gr/cc). Nilai impedansi 7000-9000 (m/s)*(gr/cc) dan nilai porositas 0,17-0,21 fraksi diindikasikan sebagai batupasir. Karakterisasi reservoar berdasarkan nilai impedansi, anomali atribut dan sebaran porositas, zona pertama dan kedua diindikasikan sebagai batupasir reservoar pada Formasi Belumai. Kata kunci:Trasing horizon, Formasi Belumai, Inversi modelbased, RMS amplitude, instantaneous frequency, envelope dan neural network.
PENDEKATAN INVERSI 1D UNTUK MENGURANGI EFEK GALVANIC PADA MODEL 2D MAGNETOTELLURIK DAERAH PANASBUMI DANAU RANAU Wibowo, Muhammad Gunadi Arif
Jurnal Geofisika Eksplorasi Vol 1, No 02 (2013)
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Metode magnetotelurik  adalah metode sounding elektromagnetik  untuk mengetahui struktur  tahanan jenis bawah permukaan dengan cara melakukan pengukuran pasif komponen medan listrik dan medan magnet alam  yang berubah terhadap waktu. Data MT tidak begitu  stabil  pada lapisan dangkal karena perbedaan topografi yang  mencolok yang disebut juga efek  galvanik  (distorsi galvanic). Untuk mengatasi data yang mengalami  shift tersebut dilakukanlah koreksi statik dengan menggunakan data TDEM. Dari informasi yang penulis dapat dari pihak Pusat Sumber Daya Geologi (PSDG), pada saat melakukan pengukuran di daerah Danau Ranau tidak menggunakan TDEM. Sehingga untuk menginterpretasikan titik-titik tersebut agar pemodelan sesuai dengan karakteristik sistem panasbumi yang diinginkan, maka penulis menggunakan pendekatan  hasil inversi 1D untuk menghilangkan efek  galvanik.  Daerah  impermeable (Claycap)  ditunjukkan oleh lapisan dengan nilai resistivitas ≤ 10 Ohm.m dengan ketebalan 700-1000 meter.  Kata kunci : Magnetotellurik, Efek galvanik, Inversi 1D, Resistivitas, Clay Cap
PEMODELAN 3D MAGNETIK MENGGUNAKAN MAG3D UNTUK IDENTIFIKASI SEBARAN BIJIH BESI DI DAERAH "RAM-UNILA" Maulana, Ardi
Jurnal Geofisika Eksplorasi Vol 1, No 01 (2013)
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Upward Continuation process to be done because he wanted to see how the boundary where the body of iron ore minerals, and Reducrion To The Pole was done because initally dipole magnetic anomalies, the process is carried out so that its response to the monopole magnetic area from 2D modeling results the model predicted the existence of iron ore minerals with susceptibility contrast amounted to 0.8585 cgs (103 SI), 1.0100 cgs (103 SI), 0,7100 cgs (103 SI) with thickness of about 25 until 50 meters which can be found at a depth of 25 meters. Which is the value of susceptibility contrast to 0.100 cgs (103 SI) to 0.122 cgs (103 SI) and a granite rock, iron ocide, pyrite, and tuff of which are associated eith the iron ore. Interpretation of results in 2D, 3D and regional geological information showed that the depth of the iron ore minerals associated with granitic rocks, iron oxides, pyrite, and iron tuff located at a depth of 15-30 meters.keywords: Upward Continuation, Reduction To The Pole, Iron Ore.
AMPLIFIKASI GEMPABUMI DAERAH SUBANG JAWA BARAT Setiani, Nani
Jurnal Geofisika Eksplorasi Vol 2, No 01 (2014)
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Geological and topographical conditions of Subang Regency complex causes of this area has huge potential earthquake. With microzonation method, the base layer frequency and waveamplitude of the can be known. The amplitude of the wave is the value of amplification. Amplification or strengthening of earthquake waves can occur because of differences indensity and velocity in sedimentary rocks which is above the basement. Amplification in Subang Regency has levels 1 to 5 times. Amplification value was highest in low plain areaswith soil-forming rock types of sedimentary rocks form coastal sediment, floodplains sediment(QAC), and plan with tuff rock types of sand, lava, pumice tuff rock (Qyt) and unrefined sediment. The amplification value is also influenced by the thickness of the sediment layer, and the elevation and slope.Keywords : microzonation, amplification.