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Analisis Geometri Akuifer Dangkal Mengunakan Metode Seismik Bias Reciprocal Hawkins (Studi Kasus Endapan Alluvial Daerah Sioux Park, Rapid Creek, South Dakota, United State of America)

BERKALA FISIKA Vol 10, No 1 (2007): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Data processing of refraction Seismic with reciprocal Hawkins method have been done by using the secondary data in area of Sioux Park, Rapid Creek, South Dakota, United State of America which  has geology structure of alluvial sediment. The sediment Alluvial has the form of water carrier rock precipitated by Rapid Creek. The result of this research are: first layer with velocity vary from 268 m/s to 347 m/s consist of clay  functioning as covering layer, the second layer have velocities 939 m/s-1829 m/s, depth 0.28 m-3.43 m and thickness 0.26 m-4.40 m, lapped  over from clay, sand, and gravel functioning as carrier coat irrigate or coated acquifer and the third layer, have velocity 1874 m/s-2216 m/s lapped over from stone napal, acts as waterproof coat (impermeable). These acquifers are unconfined aquifer. Keywords: acquifer,  seismic refraction, ground water

Estimasi Arah Strike menggunakan Metode Resistivitas Konfigurasi Persegi

BERKALA FISIKA Vol 10, No 1 (2007): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

The sounding square array resistivity method had been used to estimate strike orientation in a sub surface anomaly model. The advantage of square array are more sensitif in an anisotropic medium such as strike than inline array. Strike is an important factor to placed an array configuration in resistivity method. The array commonly lay down paralel or perpendicular with a strike depend on anomaly structure. The mapping square array was used to detect the model anomaly.The sounding square array were measured by rotating array with azimuth ,,, and . The sounding square array had an electrode spacing 1 m, 1,4 m, 2 m and 2,8 m. Azimuthal apparent resistivity was  obtained by calculation and then was plotted into Rossete diagram. The estimation of strike orientation was determined perpendicularly from maximum azimuthal apparent resistivity. The mapping square array used 10 m array spacing with 1 m electrode spacing. The Wenner array used 5 m with 0,5 m electrode spacing.Strike orientation was estimated on N 90 E. This estimation was based on result each electrode spacing on the sounding square array. The existing model anomaly were detected on 5 m until 7 m on mapping square array. The result of Wenner array modeling showed that anomaly model was detected on 2,5 m until 3,5 m on N 40 W. This result showed that the sounding square array can be applied to determine strike orientation which usually exist on geological structure Keywords: square array resistivity, strike,azimuth

Analisis Atribut Seismik untuk Identifikasi Potensi Hidrokarbon

BERKALA FISIKA Vol 9, No 4 (2006): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Rms amplitude and spectral decomposition attribute have been extracted for hydrocarbon potential identification in Amandah area, Talangakar Formation, North West Java Basin. Purpose of rms amplitude extractions is to see the change of lithology which is extreme. Example is like reservoir existence. Spectral decomposition has been used to see reservoir at thin thickness. The seismic attributes has been extracted from seismic data 3D Pre Stack Time Migration (PSTM). Log data has been taken from a well (AMD-01) to interpret and determine reservoir thickness in interest zone. Seismic attribute analysis has been used to see existence and shape of channel’s geometry spreading. The result of rms amplitude attribute extraction is reservoir which can be detected clearly at 10 ms, 20 ms, 30 ms and 40 ms window analysis. Whereas the result of spectral decomposition attribute extraction is reservoir which can be detected at 15 Hz – 25 Hz frequency with 30 ms and 40 ms window analysis. The result of rms amplitude and spectral decomposition attribute analysis shows hydrocarbon in Amandah area, Talangakar Formation is potential in channel depositional facies with depositional direction at north-south (N-S) and north nort east – south south west (NNE-SSW) and  thickness high of channel is concern at 36-60 m.   Key words: Seismic attribute, rms amplitude, spectral decomposition, reservoir,

Interpretasi Data Seismik Refraksi Menggunakan Metode Reciprocal Hawkins dan Sofware SRIM (Studi Kasus Daerah Sioux Park, Rapid City, South Dakota, USA)

BERKALA FISIKA Vol 9, No 4 (2006): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Data processing of seismic refraction has been done. This data processing was the secondary data from seismic measurement result in the Sioux Park area, Rapid City, South Dakota, USA using EG refraction & G Geometrics Model ES-1210 seismic refraction instrument made in America with 12 geophones. The seismic refraction data processing was to determined the velocity and the deepness of eachs layer, and make geology under surface model then to interpreted the the data processing result using Reciprocal Hawkins method and SRIM software. On the seismic data processing used Reciprocal Hawkins method and SRIM (Seismic Refraction Inverse Modelling) software. Reciprocal Hawkins method used time depth concept and SRIM software used delay time concept. The time depth value or the delay time value was same with a half value of intercept time.The result from the data processing using Reciprocal Hawkins method was obtained threes layer, that are the seismic wave velocity of the first layer is 1013 ft/s, the second layer is 4007 ft/s and the third layer is 6887 ft/s. While the result of the deepness calculation obtained the deep of first layer range is 0,93 ft – 11,24 ft, the second layer ranging is 8,72 ft – 19,38 ft and from data processing the result using SRIM software obtained seismic wave velocity of the first layer is 970 ft/s, the second layer is 3485 ft/s and the third layer is 6150 ft/s, while the result of deepness calculation of the first layer range is 0,10 ft – 7,20 ft, the second layer range from 3,40 ft – 27,00 ft. From the under surface image model can be interpreted that the first layer is mouldy  layer which represent cover layer, the second layer is clay stone layer, sand ( dry, having the pass character) and third layer is napal stone at Spearfish formation which has impermeable characteristic or waterproof. Key words: delay time, intercept time, Reciprocal Hawkins method, seismic refraction

Survei Resistivitas untuk Menentukan Distribusi Tahanan Jenis Batuan Bawah Permukaan Cekungan Daerah Sedimentasi Kuwu

BERKALA FISIKA Vol 9, No 4 (2006): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Geophysical survey with resistivity method has been done in Bledug area, Kuwu, Grobogan, Central Java which have geology or geophysic phenomena mud blast or mud volcano. The principle resistivity method is measurement resistivity of rock by conducting current and also measure potential difference.This survey using NANIURA Resistivitymeter Model NRD 22S. Resistivity measurement has  been done sounding with schlumberger configuration. The result 3 sounding point, northside, southside and among bledug area. Data processing using IPI version 6.0 for windows program. The result of data processing is thickness and rock resistivity. Final interpretation made with combining sounding data and geology data so that subsurface picture of resistivity distribution. The result of final interpretation shown  bledug area and surrounding is thicknesses which have a distribution resistivity of rock  has the range 0,1-1 Ωm. The conclusion that survey area is flake from salt dome.     Keywords: Bledug Kuwu, resistivity method, mud vulcano

Penentuan Kedalaman dan Ketebalan Akuifer Menggunakan Metode Seismik Bias (Studi Kasus Endapan Alluvial Daerah Sioux Park, Rapid Creek, South Dakota, United State of America)

BERKALA FISIKA Vol 9, No 3 (2006): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Data processing of refraction Seismic has been done by using the secondary data in area of Sioux Park, Rapid Creek, South Dakota, United State of America with the trajectory of seismic SP#1 which  has geology structure of alluvial sediment. The sediment Alluvial has a form of water carrier rock precipitated by Rapid Creek Tthe data processing of refraction Seismic usedin this experiment is  Reciprocal Hawkins methode that  represent a method that develop concept of time depth recognition. The time Depth from the refractor is  equal for the travel of critical time from the aspect of between refractor and surface less than time required for the ray path of projection of area refractor at a speed of refractor. Results   of  the seismic refracted obtained: first layer consist of clay  functioning as covering laye, the second layer lapped over from clay, sand, and gravel functioning as carrier coat irrigate or coat acquife and the   third layer lapped over from stone napal, functioning as waterproof coat ( impermeable). Deepness of layer acquifer vary from 0.93 ft - 12.01 ft ( 0.28 m – 3.66 m), and their thickness vary from 0.86 ft – 14.43 ft ( 0.26 m – 4.40 m). The geometry of these  acquiferare in the form of free acquifer  or unconfined aquifer. Keywords: seismic refraction, ground water

Penggambaran Pseudosection Bawah Permukaan dari Suatu Proses Evapotranspirasi Tanaman Jagung Menggunakan Program RES2DINV

BERKALA FISIKA Vol 9, No 3 (2006): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

The dipole-dipole investigation of one line corn crop subsurface condition have been done in relationship with evapotranspiration process. The variation of subsurface resistivity investigation occured by the caused of evapotranspiration process.The space of dipole-dipole array measured in 0,20 meter and 0,40 meter with n value  from 1 to 4. In May 21st,24th,28th,31st 2005 the dipole-dipole array was measured. The electrodes and  corn crop-line  possition is parallel. The depiction of subsurface condition viewed by using the Res2Dinv apparent resistivity data. The depiction showed the high resistivity of the corn crop area and the transpiration process is higher than evaporation process. Anomaly resistivity value in the pseudosection output  is 54,30 Wm. Keywords: dipole-dipole, evapotranspiration, resistivity

PEMODELAN TOMOGRAFI CROSS-HOLE METODE GEOLISTRIK RESISTIVITAS (Bentuk Anomali Silindris)

BERKALA FISIKA Vol 9, No 1 (2006): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

            Cross-hole method using an amount of electrode were placed downhole is one of tomography method. Cross-hole tomography method delineate the geological conditions of the earth surface therefore it takes an important rule in the case of anomaly monitoring. The buis concrete planted in subsurface with deepness of about 1 m were used as the source of anomaly. Tomography cross-hole data with configuration such as pole-pole, pole-bipole, bipole-pole and bipole-bipole array were taken with the depth of the borehole is 1,2 m. The space variation of one electrode to another in the hole of drill is 0,2 m, 0,4 m, 0,6 m and 0,8 m for the configuration of pole-bipole, bipole-pole and bipole-bipole. Res2Dinv program obtained the images of bipole-bipole better than the images of other configuration. While the pole-pole configuration had the worst images compared to others. It is caused by two remote electrode of pole-pole array while bipole-bipole array do not have ones. Key words: cross-hole, tomography, borehole, remote electrode

Rancang Bangun Alat Ukur Konduktivitas Panas Bahan Dengan Metode Needle Probe Berbasis Mikrokontroler AT89S52

BERKALA FISIKA Vol 9, No 1 (2006): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

A device for measuring thermal conductivity of  homogen materials using a Needle Probe method has been designed. This method uses a metal rod which emited a heat stream and a temperature sensor placed in the middle of interior heater at probe to measure changes in temperature inside the probe.            This measuring instrument represent development digitally from measuring instrument which have been made with analog system. With AT89S52 microcontroller application as data processor bases, temperature detected can be presented by sevent segment which have been controlled by BCD converter. Basically thermal conductivity measuring instrument with this Needle Probe method represent a digitally thermal detecting system which attached at Needle Probe. Every increase 1 0C, the temperature censor give output equal to 0.01 V with correctness of  displayed equal to 1 0C and error point level equal to 0.01 %. Key word: Needle Probe method, ADC, AT89S52 microcontroller, seven segment.

Studi Perbandingan Sistem Bagi Hasil Perikanan Lokal dengan Undang Undang Bagi Hasil Perikanan di Kecamatan Labuan; Jawa Barat

Buletin Ekonomi Perikanan Vol 2, No 2 (1996): Buletin Ekonomi Perikanan
Publisher : Buletin Ekonomi Perikanan

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Abstract

Indonesian government released Fisheries Sharing Law (UU Bagi Hasil Perikanan No. 16/1964) to avoid income gap among fishermen. But local fisheries sharing system stilI applied in some areas. These facts supported the research to find the reasons of institutionalization failure of fisheries sharing law. Research gain indicated that local fisheries sharing system used the same way to calculated net product among fishing gears, but different way in shared net product between owner and tenant in each gear. Fisheries sharing law used the same way to calculated net product and the same way in shared net product between owner and tenant in every fishing gear. This law were not favourable especially by the owners of gillnet and trammel net because their income will be decreased if they used it. Both fisheries sharing systems still made income gap between owner and tenant in each fishing gear and economically not suitable because unequality between opportunity and gain. Based on this comparative study, it is important to applied alternative sharing system which gave equality in product shared and economically consequences.