PENGGUNAAN TRANSFORMASI WAVELET KONTINYU UNTUK MENGANALIS GEMPA VOLKANIK GUNUNG MERAPI DAN PEMBUATAN ATRIBUT SEISMIK INDIKASI HIDROKARBON PADA EKSPLORASI MINYAK DAN GAS BUMI

• Main Authors: , Budi Eka Nurcahya, Drs. MS., , Prof. Dr. Kirbani Sri Brotopuspito
• Format: Theses and Dissertations NonPeerReviewed
• Published: [Yogyakarta] : Universitas Gadjah Mada 2014
• Subjects: ETD
• Online Access: https://repository.ugm.ac.id/130983/; http://etd.ugm.ac.id/index.php?mod=penelitian_detail&sub=PenelitianDetail&act=view&typ=html&buku_id=71418
• Institution: Universitas Gadjah Mada

The concept of wavelet transform was initially proposed by Morlet and Arens (1982) in geophysics to analyze non-stationary seismic data, then the concept of wavelet transform developed in various fields such as mathematics, digital signal processing, numerical analysis, geophysics, image processing, physics , and other fields. Wavelet transform is essentially a process of transformation using a kernel integration called 'wavelet'. The information that will be obtained in the wavelet transform is a representation of signals in the ' time domain' into 'time-frequency domain', known as ' time-frequency representation'. The process of Time frequency analysis is done by convolution of signal with a wavelet. At the time frequency analysis, frequency resolution is obtained by dilatation the wavelet at certain scale and time resolution is obtained by translation the wavelet at factor of translation. Combination of the scale and translation values in the analysis of time-based frequency CWT (Continuous Wavelet Transform) will provide analytical results that have a high resolution. The analysis data in the time-frequency domain based on CWT can overcome the disadvantages of the process of analysis data in the time-frequency domain based on STFT (Short Time Fourier Transform). The limitation of STFT method at the process of analysis data in the time-frequency domain is located on the fixed window selection . The selection of a narrow window will give low frequency resolution and the selection of a wide window will give low time resolution. The application of continuous wavelet transform in the analysis of Merapi Volcanoe�s seismic data is to find out more clearly changes of the frequency content of MP earthquake, earthquake avalanches, VTB, volcanic tremor, an initially of hot cloud earthquake from Mount Merapi in the time-frequency domain, and to analyze occurrence of very interesting recurrence of MP earthquake and a large lava flow occurred on 21 to October 31, 1996. High-resolution spectrum analysis, coherence, rektilinieritas, planaritas, the degree of polarization, incidence angle and the apparent azimuth angle for MP earthquake that occurred on December 21 to October 31, 1996 by using a continuous wavelet transform (Morlet wavelet), can be used to infer the location of the earthquake source MP and adjacent or similar source mechanisms. and can be used to analyze the time interval between of recurring MP earthquakes. A recurrence of a time interval between MP earthquakes that occurred on December 21 to October 31, 1996 seem similar to time interval of slip occurrence of a solution of differential equations motion of stick -slip model of visco-elastic slab. With the similarity occurrence between the model and the observation result, we can conclude that the dynamics of MP earthquake recurrence is controlled by the increase of velocity V or pressure and friction. This information can be used to an illustration that the lava dome growth of Mount Merapi in 1996 was controlled by increasing force inside the body of Mount Merapi at the increasing of Mount Merapi volcanic activity. The use of continuous wavelet transform for analysis 2D and 3D seismic data to oil and gas exploration is the application of complex wavelet (Morlet wavelet) for generating seismic attributes, the spectral decomposition, and for generating the gradient amplitude attribute (GAMP). The GAMP attribute that is generated by using the continuous wavelet transform can describe the hydrocarbon anomalies in the stratigraphic reservoir or the combination of structural and stratigraphic reservoir. The application combination of seismic attributes GAMP as a result of continuous wavelet transform with inversion attributes: simultaneous inversion (Vp / Vs, Vp, Vs, density, AIp, AIs, (Lamda-Rho), and (Mu-Rho)), AVO (A �B) and the value ) ( / ) ( f H f V as the result of three-components microtremor measurement that is calculated by using the continuous wavelet transform, can be used to detect the presence of hydrocarbons. This successful method can be proved from the results of drilling.