Identifikasi Orientasi Arah Dominan Rekahan Di Lapangan Panasbumi Melalui Analisa Shear Wave Splitting (SWS)

Kurnia, Valda Anggita (2020) Identifikasi Orientasi Arah Dominan Rekahan Di Lapangan Panasbumi Melalui Analisa Shear Wave Splitting (SWS). Masters thesis, Institut Teknologi Sepuluh November.

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Abstract

Salah satu bagian ilmu geofisika yang cukup efektif untuk mengkaji gempa bumi dan struktur dalam bumi adalah seismologi. Indonesia tergolong dengan adanya banyak aktivitas seismic yang terjadi pada lapangan panas bumi dapat digunakan untuk memantau kondisi reservoir panas bumi. Selain itu, injeksi fluida pada saat produksi dapat menyebabkan tekanan yang arahnya melawan formasi batuan sehingga membentuk rekahan hidrolik (hydraulic fracture). Metode Shear Wave Splitting adalah melakukan pendeketan antara hasil polarisasi (φ) dan waktu tunda (δt) berdasarkan polarisasi gelombang S akan menghasilkan ketebalan dari lapisan anisotropi atau ukuran dari rekahan mikro. Arah polarisasi tiap stasiun perekam gempa dalam peta geologi memperlihatkan arah dominan rekahan yang cukup konsisten, yaitu arah NWSE. Ketiga stasiun menunjukkan arah polarisasi yang terintegrasi dengan keberadaan sesar lokal di bawah permukaan. Sebagaimana arah rekahan dominan yang merepresentasikan arah NW-SE, persebaran sumber gempa mikro pun menunjukkan arah yang sama.Berdasarkan peta kontur intensitas rekahan, memperlihatkan rentang nilaiintensitas rekahan yang cukup rapat berkisar antara 6,6 – 8,0 ms/km. Persebaran nilai intensitas rekahan yang tinggi berada pada area stasiun ZTO, ZPN, ZUI, BRK,BRB, yaitu sebelah selatan lokasi penelitian. Sementara itu, persebaran nilai intensitas rekahan yang rendah berada pada area stasiun ULI, GZM, BAN, GBZ, BUT, yaitu sebelah barat dan timur lokasi penelitian. Tingginya nilai intensitas rekahan yang disertai dengan banyaknya intensitas struktur memperkuat prediksi terhadap zona aliran panasbumi. ========================================================= One part of geophysical science that is effective enough to study earthquakes and structures in the earth is seismology. Indonesia is classified as having a lot of seismic activities that occur in the geothermal field can be used to monitor the condition of the geothermal reservoir. In addition, fluid injection during production can cause pressure in the direction of opposing rock formations to form hydraulic fractures. The method of Shear Wave Splitting is to shorten the results of polarization (φ) and delay time (δt) based on the polarization of the S wave will produce thickness of the anisotropy layer or the size of the micro fracture.The polarization direction of each earthquake recording station in the geological map showing a fairly consistent dominant direction of the fracture, namely the direction of the NW-SE. All three stations show a polarization direction that is integrated with the presence of local faults below the surface. As the dominant fracture direction represents the NW-SE direction, the distribution of micro earthquake sources also shows the same direction. Based on the fracture contour map, the fracture intensity range that is quite dense ranges from 6.6 - 8.0 ms / km. The distribution of high fracture intensity values is in the ZTO, ZPN, ZUI, BRK, BRB station areas, which are south of the study site. Meanwhile, the distribution of low fracture intensity values is in the ULI, GZM, BAN, GBZ, BUT station areas, which are west and east of the study site. The high value of fracture intensity accompanied by the number of structural intensities reinforces the prediction of geothermal flow zone.

Item Type: Thesis (Masters)
Additional Information: RTG 551.22 Kur i-1 • Kurnia, Valda Anggita
Uncontrolled Keywords: Mikroseismik, Arah Polarisasi, Intensitas Rekahan,Microroseism, Polarization Direction, Fracture Intensity
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
T Technology > TD Environmental technology. Sanitary engineering > TD890 Global Environmental Monitoring System
T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK1318 Geothermal Power Plants
Divisions: Faculty of Civil Engineering and Planning > Geomatics Engineering > 29101-(S2) Master Thesis
Depositing User: VALDA ANGGITA KURNIA
Date Deposited: 14 Aug 2020 04:34
Last Modified: 19 Nov 2020 03:36
URI: http://repository.its.ac.id/id/eprint/78121

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