Awali Priyono
Fakultas Teknik Pertambangan dan Perminyakan Institut Teknologi Bandung, Bandung

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Metode Seismik Dalam Usaha Pendeteksian Reservoir Minyak Dan Gas Bumi (Penerapan Metode AVO) Awali Priyono
Jurnal Matematika & Sains Vol 5, No 1 (2000)
Publisher : Institut Teknologi Bandung

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In this paper, a study of AVO (Amplitude Versus Off-Set) technique as hydrocarbon detection will be presented. The study have been carried out in the carbonate and sandstone reservoirs. AVO analysis, as showed in the range limited off set, indicates that dry carbonate, water or gas in the carbonate reservoir can be recognized from their amplitude responses. The difference in Poissons ratio value between water and gas in the carbonate reservoir is relative small, therefore care must be taken in the analysis. The study shows that, in the case of sandstone reservoar, the AVO response does not depend on the gas saturation, but this is not the case for oil saturation. AVO inversion using Damp Approximation Inverse (DAI) gives good accuracy, therefore this method is very helpful in estimating the elastic parameters such as Poissons ratio and modulus Young in relation to reservoir characterization.
Perbandingan Hasil Atenuasi Tomografi 3D Menggunakan Metoda Spectral Fitting & Spectral Ratio Dalam Usaha Pemetaan Bawah Permukaan (Studi Kasus Gunung Guntur) Awali Priyono; Gede Suantika; Sri Widiyantoro
Jurnal Matematika & Sains Vol 15, No 3 (2010)
Publisher : Institut Teknologi Bandung

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Spectral fitting and spectral ratio methods are tested to estimate the Q value or attenuation in the effort on imaging the subsurface structure using three-dimensional tomographic inversion techniques. In this study, we used microearthquakes data around Mount Guntur that was collected from 1995 until 2007 that consist of 4800 seismograms. Analyses using the spectral fitting and spectral ratio methods generally depict the same anomalous areas. Studies using P and S waves indicate that the area of high attenuation corresponds to the area of low velocity that extending from mount Guntur to Kamojang caldera. In terms of the image quality, it can be seen that the attenuation derived using the spectral ratio of S wave has the same pattern with the one derived using P wave. This is due to the attenuation of S wave, which was derived directly from the P-wave. The Q value in the spectral ratio method depends on the width of the frequency window taken and the effect of noise in the determination the slope of the linear relationship between the natural logarithm of spectral ratio with frequency. The result of the spectral fitting analysis shows that the pattern of S wave attenuation image is different from the pattern inferred from the P wave data, because each attenuation image has been determined separately and does not depend on each other. Since the sensitivity of the values of Qp and Qs are important in fluid rock identification, the determination of Qs should not depend directly on Qp. With the various reasons above and more influential factor in estimating the value of Q using spectral ratio, the spectral fitting method is more recommendable to be employed to determine the value of Q.
Implementation of Filter Picker Algorithm For Aftershock Identification of Lombok Earthquake 2018 A. Ardianto; Y.M. Husni; A. D. Nugraha; M. Muzli; Z. Zulfakriza; H. Afif; David P. Sahara; Sri Widiyantoro; Awali Priyono; Nanang T. Puspito; Pepen Supendi; A. Riyanto; Shengji Wei; B. S. Prabowo
Jurnal Geofisika Vol 17 No 1 (2019): Jurnal Geofisika
Publisher : Himpunan Ahli Geofisika Indonesia (HAGI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (8338.28 KB) | DOI: 10.36435/jgf.v17i1.397

Abstract

The ability to identify earthquake events that are consistent, efficient and accurate is increasingly needed along with the increase in the amount of data analyzed. In this paper a filter picker algorithm is implemented to identify aftershock events and determination of arrival time automatically, especially for the P wave phase. Here modifications are made in determining the uncertainty of arrival time and there are additional criteria in determining the time of arrival used. The additional criteria are that in a certain time span, there are at least 5 stations determined by the time the filter picker arrives. This is done to minimize identification errors due to local noise and other practical reasons, namely the minimum number of stations to determine the location and other seismological analysis. To test the filter picker algorithm, aftershock data from the Lombok earthquake occurred on July 29 (M 6.4), August 5 (M 7), and August 19 (M 6.3 and M 6.9) 2018. The aftershock data were used for 30 days, from August 4, 2018 to September 4, 2018 using local seismic station in Lombok Island. The results of the filter picker algorithm were evaluated by comparing the number of earthquake events detected and the accuracy of determining the P wave arrival time automatically to the results of manually arriving time. In addition, a comparison of the results obtained from a broadband type seismometer with a short period is used to find out how much influence the type of tool has on its performance results. The results of the comparison with the manual arrival time show that more than 85 percent of the results of the automatic arrival time have a difference below 0.2 seconds. Therefore, it can be said that the filter picker algorithm is quite effective for identifying events and determining the arrival time of P waves. In this paper it is also shown that this algorithm can be used for broad band and short period seismometer sensor, even without the prior correction of instruments.