Jurnal Geofisika Eksplorasi
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IDENTIFIKASI DAN ESTIMASI SUMBER DAYA BATUBARA MENGGUNAKAN METODE POLIGON BERDASARKAN INTEPRETASI DATA LOGGING PADA LAPANGAN â€ADAâ€, SUMATERA SELATAN
Full text linkAs petroleum reserves depleted, certainly encourage the government to search for new energy sources. Eksploration of coal is the right choice because  its potential is so great in Indonesian especially in South Sumatera Province is known have content 37,80% from total resources in Indonesian. Well loggging method is one of geophysics method used to find and estimate coal resources. Advantages of well logging method is able to describe subsurface laterally. The purpose of this study is displaying an overview of subsurface rock layers, determine the direction of distribution by correlating coal seam between wells based on data logging, and to estimate coal resources in the research area. The total area of the author's research is 442.056 m2 has 10 wells. Log data used in this study is gamma ray log dan density log, where coal seams are characterized by gamma ray log response and low log density responses. On the field â€ADA†found four coal seam, that is seam A1 with thickness 8,28 m, seam A2 with thickness 13,62 m, seam B with thickness 18,50, and seam C with thickness 8,84. Direction of coal distribution from South to North with slope angle 5-30º and direction of sincerity from East to West. The author calculates the estimated coal resource using polygon method because this calculates method can be done with a short time and the results are right. Total coal by polygon method of 18.322.653 m3 in tons of 21.987.184–27.483.980 ton while calculations with software rock works 15 amount 18.786.254 m3 in tons of 22.543.505–28.179.381 ton
ESTIMASI NILAI POROSITAS DAN PERMEABILITAS DENGAN PENDEKATAN DIGITAL ROCK PHYSICS (DRP) PADA SAMPEL BATUPASIR FORMASI NGRAYONG, CEKUNGAN JAWA TIMUR BAGIAN UTARA
Full text linkReservoir rock permeability and porosity are physical properties of rocks that control reservoir quality. Conventionally, rock porosity and permeability values are obtained from measurements in the laboratory or through well logs. At present, calculation of porosity and permeability can be calculated using digital image processing / Digital Rock Physics (DRP). Core data samples are processed by X-ray diffraction using CT-micro-tomography scan. The result is an image model of the core sample, 2D and 3D images. The combination of theoretical processing and digital images can be obtained from the value of porosity and permeability of rock samples. In this study, we calculated porosity and permeability values using the Digital Rock Physics (DRP) approach in sandstone samples from the Ngrayong Formation, North East Java Basin. The results of the digital image simulation and processing on the Ngrayong Formation sandstone samples ranged in value from 33.50% and permeability around 1267.02 mDarcy
OPTIMALISASI PENCITRAAN STRUKTUR BAWAH PERMUKAAN MENGGUNAKAN METODE KIRCHHOFF PRE-STACK TIME MIGRATION PADA DATA SEISMIK LAUT WETAR
Full text linkMigration is one of the stages in seismic data processing aimed at returning the diffraction effect to the actual reflector point. The processing of a seismic data is adjusted to the existing problems in the data itself, so the accuracy in using the migration technique and determination of data processing parameters greatly affects the resulting seismic cross-section. Kirchhoff Pre-Stack Time Migration is one of the most used migration methods in seismic data processing because it shows better results than conventional stacking methods. The parameters that need to be noticed in the Kirchhoff migration are the migration aperture values. Based on this, variations of migration aperture values used are 75 m, 200 m and 512.5 m. The 512.5-m aperture migration value shows the best seismic cross-section results. This is evidenced by the capability in eliminating bowtie effects around CDP 600 up to CDP 800, eliminating diffraction effects around CDP 3900 to CDP 4050, and showing a seismic cross-section with better lateral resolution compared to the migration value of the aperture of 75 m and 200 m. Based on the seismic cross-section of migration results, the geological structure that can be identified is a fault that found in some CDP
Engineering Gology Model of Bener Dam Diversion Tunnels in Geological Risk Disaster Mitigation
Full text linkThe Bener Dam Diversion Tunnel Plan is located in Bener District, Purworejo Regency. Engineering geology mapping data, drillimg data and laboratory data used as primary data. Surface and subsurface analysis show that each rock unit has different index and mechanical properties. Generally, the rock mass quality conditions in the dam belonged to good Rock (80%) in the Rock Mass Rating (RMR) system (Bieniawski, 1989). Â The other rock mass quality type also found among them fair rock (5%), poor rock (5%), and very poor rock (10%). Poor rock mass quality conditions were controlled by geological structures, especially faults that partially cut through the tunnel geometry. The very poor quality of rock mass was in the volcanic lens (loose sand material) did not cut through the tunnel path. The difference stand-up time of the rock on the tunnel requires proper mitigation (Nguyen & Nguyen, 2015). The stand-up time belonged to the dangerous condition was in the fault zone with poor rock mass quality, while the lens with very bad rock mass quality did not affect the stability of the excavation of the tunnel
ROCK FORMATION AND SITE CLASS IN BANDAR LAMPUNG
Full text linkSoil characteristics are important impact for the scale of damage caused by earthquake vibrations. The impact caused by an earthquake in a location depends on the shear wave velocity (Vs). The study examined the effect of sedimentary rock formations on shear wave velocity and site class based on SPT tests in two rock formations in Bandar Lampung. The value of Vs, Vs30 and site class is determined based on the N-SPT value. Older rock formations of Quaternary age, have produced compaction at a shallow depth of 2 m from the surface, with Vs30 360 m/s and site class C. While the formation is younger, compactions are formed at a depth of 20 m, Vs 30 200 m/s and site class D