MODEL SISTEM PANAS BUMI LAPANGAN KARAHA - TALAGA BODAS BERDASARKAN INVERSI 2D DATA MAGNETOTELLURIK

Ilham Arisbaya; Aldinofrizal Aldinofrizal; Yayat Sudrajat; Eddy Zulkarnaini Gaffar; Asep Harja

doi:10.14203/risetgeotam2018.v28.989

MODEL SISTEM PANAS BUMI LAPANGAN KARAHA - TALAGA BODAS BERDASARKAN INVERSI 2D DATA MAGNETOTELLURIK

Ilham Arisbaya, Aldinofrizal Aldinofrizal, Yayat Sudrajat, Eddy Zulkarnaini Gaffar, Asep Harja

Abstract

Daerah Karaha-Talaga Bodas, yang terletak di kawasan Utara Gunung Galunggung, Tasikmalaya diduga memiliki prospek panas bumi, dengan adanya manifestasi permukaan berupa fumarol dan mata air panas. Metode Magnetotelurik (MT) diaplikasikan untuk mengidentifikasi struktur resistivitas bawah permukaan yang terkait dengan sistem panas bumi. Pengolahan data MT dilakukan melalui beberapa tahap, yaitu transformasi Fourier, seleksi crosspower, analisis rotasi, analisis kontak vertikal dan inversi dengan hasil akhir berupa model sebaran 2D. Hasil pengolahan data menunjukan adanya lapisan konduktif dengan nilai resistivitas 1-10 Ohm.m, yang diduga berperan sebagai lapisan penudung. Zona reservoir berupa daerah dengan nilai resistivitas 10-100 Ohm.m. Nilai resistivitas yang lebih besar dari 100 Ohm.m berkorelasi dengan batuan beku yang biasa dianggap sebagai sumber panas. Interpretasi hasil pengolahan data MT diintegrasikan dengan informasi geologi untuk mendapatkan gambaran sistem Panas Bumi Karaha-Talaga Bodas.

The area of Karaha-Talaga Bodas, at the north of Mount Galunggung, Tasikmalaya, was expected to have a geothermal prospect due to several surface manifestations of fumaroles and hot springs. The Magnetotelluric method (MT) was then applied in this area to identify the subsurface resistivity structure related to the geothermal system. The MT data processing included Fourier transform, crossover selection, rotation analysis, vertical contact analysis, and inversion, with the result of a 2D resistivity model. The resistivity model indicated the existence of a conductive layer with the resistivity value of 1-10 Ohm.m, which could be a caprock. The reservoir zone is the area with the resistivity value of 10-100 Ohm.m. The resistivity value greater than 100 Ohm.m correlates with the basement, that acted as the heat source. Interpretation of the MT model was then integrated with the geological information to get an overview of the Karaha-Talaga Bodas geothermal system.

Keywords

Geothermal, Karaha-Talaga Bodas, Magnetotelluric, Resistivity.

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References

Allis, R., and Moore, J. N., 2000. Evolution of Volcano-Hosted Vapor-Dominated Geothermal Systems. Geothermal Resources Council Transactions, 211-216.

Allis, R., Moore, J. N., Mcculloch, J., Petty, S., and Derocher, T., 2000. Karaha-Telaga Bodas, Indonesia: A Partially Vapor-Dominated Geothermal System. Geothermal Resources Council Transactions, 217 – 222.

Andrieux, P., and Wightman, W. E., 1984. The so-called static corrections in magnetotelluric measurements. Proceedings 54th Annual International Meeting, SEG, Abstracts. 43-44.

BPS, 2017. Statistik Indonesia 2017, Jakarta: Badan Pusat Statistik.

Bronto, S., 1989. Volcanic geology of Galunggung, West Java, Indonesia. University of Canterbury.

Budhitrisna, T., 1986. Peta Geologi Lembar Tasikmalaya, Pusat Survei Geologi.

Cumming, W., and Mackie, R., 2010. Resistivity Imaging of Geothermal Resources Using 1D , 2D and 3D MT Inversion and TDEM Static Shift Correction Illustrated by a Glass Mountain Case History. Proceedings World Geothermal Congress (April), 1–10.

Fauzi, A., Permana, H., and Indarto, S., 2015. Regional Structure Control on Geothermal Systems in West Java, Indonesia, World Geothermal Congress, 19–25.

Garcia, X., and Jones, A. G., 2002. Atmospheric sources for audio-magnetotelluric (AMT) sounding. Geophysics 67(2), 448–458. DOI:10.1190/1.1468604.

Geosystem, 2008. WinGLink: A guide, Milan.

Hansen, P. C., 1992. Analysis of discrete ill-posed problems by means of the L-Curve. SIAM Journal on Scientific Computing 34(4), 561–580. DOI:10.1137/1034115.

Hersir, G. P., and Bjornsson, A., 1991. Geophysical exploration for geothermal resources: principles and application, Reykjavik: UNU Geothermal Training Programme.

Jones, A. G., and Groom, R. W., 1993. Strike-angle determination from the magnetotelluric impedance tensor in the presence of noise and local distortion: rotate at your peril! Geophysical Journal International 113(2), 524–534.

DOI:10.1111/j.1365-246X.1993.tb00905.x.

Maryanto, S., Dewi, C. N., Syahra, V., Rachmansyah, A., Foster, J., Nadhir, A., and Santoso, D. R., 2017.

Magnetotelluric-Geochemistry Investigations of Blawan Geothermal Field, East Java, Indonesia. Geosciences 7(2), 41. DOI:10.3390/geosciences7020041.

Moore, J. N., Allis, R., Renner, J. L., Mildenhall, D., and McCulloch, J., 2002. Petrologic Evidence for Boiling To Dryness in the Karaha-Telaga Bodas Geothermal System, Indonesia. Twenty-SeventhWorkshop on Geothermal Reservoir Engineering, 98–108.

Nemčok, M., McCulloch, J., Nash, G., and Moore, J., 2001. Fault Kinematics in the Karaha-Telaga Bodas, Indonesia, Geothermal Field_An Interpretation Tool for Remote Sensing Data. In Geothermal Resources Council Transactions, 765-770.

Nemčok, M., Moore, J. N., Christensen, C., Allis, R., Powell, T., Murray, B., and Nash, G., 2007. Controls on the Karaha–Telaga Bodas geothermal reservoir, Indonesia. Geothermics 36(1), 9–46. DOI:10.1016/j.geothermics.2006.09.005.

Parkinson, W. D., 1959. Directions of Rapid Geomagnetic Fluctuations. Geophysical Journal Of The Royal Astronomical Society 2(1), 1–14. DOI: 10.1111/j.1365-246X.1959.tb05776.x.

Pellerin, L., and Hohmann, G. W., 1990. Transient electromagnetic inversion: A remedy for magnetotelluric static shifts. Geophysics 55(9), 1242–1250. DOI: 10.1190/1.14429 40.

PhoenixGeophysics, 2005. Data Processing User Guide.

Powell, T., Moore, J., DeRocher, T., and McCulloch, J., 2001.

Reservoir Geochemistry of the Karaha - Telaga Bodas Prospect, Indonesia. Geothermal Resources Council Transactions, 363–367.

Qahhar, M. R. A., Daud, Y., Pratama, S. A., Zarkasyi, A., Sugiyanto, A., and Suhanto, E., 2015. Modeling of Geothermal Reservoir in Lawu field Using 2-D Inversion of Magnetotelluric Data. Proceedings Indonesia Geathermal Convention & Exhibition. Jakarta, 1-5.

Raharjo, I. B., Allis, R. G., and Chapman, D. S., 2016. Geothermics Volcano-hosted vapor-dominated geothermal systems in permeability space. Geothermics 62, 22–32. DOI: 10.1016/j.geothermics. 2016.02.005.

Raharjo, I. B., Wannamaker, P., Allis, R., and Chapman, D., 2002. Magnetotelluric interpretation of the Karaha Bodas geothermal field Indonesia. Proceeding Twenty-Seventh Workshop on Geothermal Reservoir Engineering Stanford University. Stanford: Stanford Geothermal Program.

Rodi, W., and Mackie, R. L., 2001. Nonlinear conjugate gradients algorithm for 2-D magnetotelluric inversion. Geophysics 66 (1), 174 – 187. DOI:10.1190/ 1.1444893.

RUPTL-PLN, 2017. Rencana Usaha Penyediaan Tenaga Listrik PT. PLN Tahun 2017-2026, Jakarta.

Saputra, R. M., and Widodo, 2017. Synthetic Modeling of A Geothermal System Using Audio-magnetotelluric (AMT) and Magnetotelluric (MT). Southeast Asian Conference on Geophysics. IOP Conf. Series: Earth and Environmental Science. IOP Conference Series: Earth and Environmental Science. DOI: 10.1088/ 1755-1315/62/1/012036.

Simpson, F., and Bahr, K., 2005. Practical Magnetotellurics, Cambridge, Cambridge University Press. DOI: 10.1017/CBO9780 511614095.

Singarimbun, A., Gaffar, E. Z., and Tofani, P., 2017. Modeling of Reservoir Structure by Using Magnetotelluric Method in the Area of Mt. Argopuro, East Java, Indonesia. Journal of Engineering and Technological Sciences 49(6), 833. DOI:10.5614/j.eng. technol.sci.2017.49.6.9.

Stark, M. A, Soyer, W., Hallinan, S., and Watts, M. D., 2013. Distortion Effects on Magnetotelluric Sounding Data Investigated by 3D Modeling of High-Resolution Topography. GRC Transactions 37.

Statistik-EBTKE, 2016. Statistik EBTKE 2016, Jakarta.

Statistik-Ketenagalistrikan, 2016. Statistik Ketenagalistrikan 2016 30th ed., Jakarta: Direktorat Jenderal Ketenagalistrikan KESDM RI.

Sternberg, B. K., Washburne, J. C., and Pellerin, L., 1985. Correction for the static shift in magnetotellurics using transient electromagnetic soundings. Geophysics 53(11), 1459–1468. DOI:10.1190/ 1.14424 26.

Sudradjat, A., and Tilling, R., 1984. Volcanic Hazards in Indonesia The 1982-83 Eruption of Galunggung. Episodes 7(2), 19.

Swift, C. M., 1967. A Magnetotelluric Investigation of an Electrical Conductivity Anomaly in the Southwestern United States. Massachusetts Institute of Technology.

Tripp, A., Moore, J., Ussher, G., and McCulloch, J., 2002. Gravity Modeling of the Karaha - Telaga Bodas Geothermal System, Indonesia. Procedings, Twenty-seventh Workshop on Geothermal Reservoir Engineering Stanford University.

Stanford: Stanford Geothermal Program.

Ussher, G., Harvey, C., Johnstone, R., and Anderson, E., 2000. Understanding the resistivities observed in geothermal systems. Proceedings World Geothermal Congress. Kyushu, 1915–1920.

Vozoff, K., 1991. 8. The Magnetotelluric Method. In Electromagnetic Methods in Applied Geophysics. Investigations in Geophysics. Society of Exploration Geophysicists. DOI:10.1190/ 1.9781560802686.ch8.

Watts, M. D., Mackie, R., Scholl, C., and Hallinan, S., 2013. Limitations of MT static shift corrections using time-domain EM data. SEG Technical Program Expanded Abstracts, 681–684. DOI:10.1190/segam2013-1078.1.

Wiese, H., 1962. Geomagnetische Tiefentellurik Teil II: Die Streichrichting der Undergrundstrukturn des Elektrischen Widerstandes, Erschlossen Aus Geomagnetischen Variationen. Geofisica pura e applicata 52(1), 83–103. DOI :10. 1007/BF01996002.

Zhang, L., Hao, T., Xiao, Q., Wang, J., Zhou, L., Qi, M., Cui, X., and Cai, N., 2015. Magnetotelluric investigation of the geothermal anomaly in Hailin, Mudanjiang, Northeastern China. Journal of Applied Geophysics 118, 47–65.

DOI: http://dx.doi.org/10.14203/risetgeotam2018.v28.989