Analisis Shear Wave Splitting Dalam Penentuan Orientasi Arah Rekahan Mikro Pada Lapangan Panas Bumi ‘X’.

Widyanti, Amanda Putri (2022) Analisis Shear Wave Splitting Dalam Penentuan Orientasi Arah Rekahan Mikro Pada Lapangan Panas Bumi ‘X’. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Produksi pada lapangan panas bumi dapat dikembangkan dengan berbagai cara, salah satunya dengan analisis arah rekahan. Hal ini disebabkan orientasi arah rekahan mikro dapat menyajikan data acuan yang nantinya dapat digunakan untuk menentukan zona reservoir. Analisis metode Shear Wave Splitting digunakan untuk memperoleh informasi struktur geologi lapangan panas bumi mengenai orientasi arah rekahan bawah permukaan. Parameter Shear Wave Splitting seperti arah polarisasi (φ) dan waktu tunda (δt) pada gelombang S dapat dihitung dengan menggunakan metode cross-correlation. Dalam menentukan orientasi arah rekahan, pengolahan diawali dengan picking dan quality controll waveform 3 komponen dengan menggunakan software Seissgram2k sehingga didapatkan nilai ts - tp< 3. Jika selisih nilai ts tp telah sesuai kriteria, konversi file .mseed waveform 3 komponen dilakukan sehingga menjadi file .sac yang nantinya akan digunakan sebagai input pada software Matlab. Data waveform .sac lalu di filter dengan rentangg frekuensi 1.5 – 8 Hz sehingga picking gelombang P dan S dilakukan ulang untuk mendapatkan nilai tp dan ts terbaik. Rotasi gelombang horizontal kearah radial dan tangensial dilakukan untuk mempermudah dalam pengolahan data selanjutnya. Sudut rotasi dengan rentang 0⁰ hingga 180⁰ dengan penambahan 1⁰. Selanjutnya dilakukan korelasi sehingga mendapatkan kontur nilai korelasi silang antara gelombang arah radial dan tangensial. Nilai koordinat hasil korelasi silang yang paling tinggi dianggap sebagai parameter Shear Wave Splitting, dimana sudut polarisasi pada absis dan waktu tunda gelombang pada ordinatnya. (Palgunadi, 2016). Sehingga dapat dilakukan plotting pada diagram rosette dan diketahui bahwa orientasi arah rekahan dominan pada arah NE-SW. Rata-rata nilai dtSWS berkisar antara 0.015 - 0.056 sekon. Melalui hasil tersebut, maka dapat digunakan sebagai data penunjang untuk menunjukkan densitas rekahan yang nantinya dapat memperlihatkan area permeabilitas serta menunjukkan zona anisotropi.
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Production in geothermal fields can be developed in various ways, one of which is by analysis of fracture directions. This is because the orientation of the micro-fracture direction can provide reference data that can later be used to determine the reservoir zone. Analysis of the Shear Wave Splitting method is used to obtain information on the geological structure of the geothermal field regarding the orientation of the subsurface fractures. Shear Wave Splitting parameters such as polarization direction (φ) and delay time (δt) on the S wave can be calculated using the cross-correlation method. In determining the orientation of the fracture direction, the processing begins with picking and quality control of the 3-component waveform using the Seissgram2k software so that the value of ts - tp<3 is obtained. sac which will be used as input in the Matlab software. The .sac waveform data is then filtered with a frequency range of 1.5 – 8 Hz so that the picking of P and S waves is repeated to get the best tp and ts values. Horizontal wave rotation towards radial and tangential is done to facilitate further data processing. Rotation angle with a range of 0⁰ to 180⁰ in increments of 1⁰. Furthermore, correlation is carried out so as to get the contour of the cross-correlation value between the radial and tangential waves. The coordinate value of the highest cross-correlation is considered as the SHEAR WAVE SPLITTING parameter, where the polarization angle is at the abscissa and the wave delay time is in the ordinate. (Palgunadi, 2016). So that it can be plotted on the rosette diagram and it is known that the orientation of the dominant fracture direction is in the NE-SW direction. The average dtShear Wave Splitting value ranges from 0.015 - 0.056 seconds. Through these results, it can be used as supporting data to show the fracture density which can later show the area of permeability and indicate the anisotropy zone.

Item Type:	Thesis (Other)
Additional Information:	RSGf 551.2 Wid a-1 2022
Uncontrolled Keywords:	Gempa Mikro, Orientas Arah Rekahan, Shear Wave Splitting. Micro Earthquakes, Fracture Directional Orientation, Shear Wave Splitting.
Subjects:	Q Science > QE Geology > QE538.8 Earthquakes. Seismology
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geomatics Engineering > 29202-(S1) Undergraduate Thesis
Depositing User:	Mr. Marsudiyana -
Date Deposited:	21 May 2026 06:41
Last Modified:	21 May 2026 06:41
URI:	http://repository.its.ac.id/id/eprint/133312

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