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Abstrak :
Sumur Meranji-1 menemukan cadangan hidrokarbon pada Formasi Batupasir Namur di Struktur Meranji yang terletak pada Lapangan Merrimelia, Cekungan Eromanga, Australia. Cekungan ini terbentuk mulai kurun waktu Awal Jurassic hingga Akhir Cretaceous dan didominasi oleh lingkungan pengendapan braided, meandering fluvial, shoreface serta lacustrine turbidite sandstone sehingga memiliki reservoar yang cukup tebal dan sangat potensial untuk menjadi lapangan produksi. Walaupun memiliki potensi untuk menjadi lapangan produksi, lapangan ini belum memiliki peta distribusi reservoar yang dapat digunakan untuk pengembangan lapangan lebih lanjut. Oleh karena itu, studi karakterisasi reservoar dilakukan dengan metode inversi seismik dan dekomposisi spektral untuk menghasilkan peta distribusi reservoar ini. Metode inversi seismik menghasilkan penampang impedansi akustik yang dapat diasosiasikan dengan litologi reservoar sedangkan metode dekomposisi spektral menghasilkan penampang frekuensi yang dapat diolah dan dianalisis lebih lanjut untuk mengidentifikasi keberadaan fluida reservoar. Studi dekomposisi spektral dimulai dengan mengekstrak frekuensi data seismik setiap kelipatan 1 Hz dari frekuensi 1 Hz sampai dengan frekuensi 60 Hz. Penampang frekuensi ini kemudian diolah untuk menghasilkan frequency gather pada perpotongan inline dan xline di lokasi terdekat dengan Sumur Meranji-1. Dari frequency gather ini kemudian ditarik horizon pada zona reservoar minyak, gas dan air lalu diplot pada grafik amplitudo vs frekuensi. Dari grafik ini selanjutnya ditentukan zona low (frekuensi 9-13 Hz), mid (frekuensi 16-20 Hz) dan high (frekuensi 35-39 Hz) lalu dilakukan operasi aritmatika sebagai berikut: zona mid dikurangi zona low (disebut zona mL), zona high dikurangi zona mid (disebut zona Hm) dan zona mL dikali dengan zona Hm yang disebut zona Hm*mL. Zona mL akan menampilkan zona-zona keberadaan gas sedangkan zona Hm*mL akan menampilkan zona-zona keberadaan minyak. ......Meranji-1 well discovered hydrocarbon reserves in the Namur Sandstone Formation which is located on Meranji Structure in Merrimelia Field, Eromanga Basin, Australia. This basin was formed from the period of Early Jurassic to Late Cretaceous and the depositional environment is dominated by braided, meandering fluvial, shoreface and lacustrine turbidite sandstone that have a fairly thick reservoir and very potential to be a producing field. Although it has the potential to become a producing field, the field does not have any reservoir distribution maps that can be used for further field development. Therefore, reservoir characterization studies conducted using seismic inversion and spectral decomposition methods to produce these reservoir distribution maps. Seismic inversion method produces an acoustic impedance section that can be associated with reservoir lithology while spectral decomposition method produces a frequency section which can be further processed and analyzed to identify the presence of the reservoir fluid. Spectral decomposition study begins with seismic data extraction for every single frequency from 1 to 60 Hz. These frequency sections then processed to produce a frequency gather at the intersection of inline and xline near Meranji-1 well. From this frequency gather then drawn a horizon at oil, gas and water reservoir zone and then plotted on a frequency vs amplitude graph. Based on this graph; low (frequency 9-13 Hz), mid (frequency 16-20 Hz) and high (frequency 35-39 Hz) zone is defined and then performed an arithmetic operation as follows: mid zone minus the low zone (called mL zone), high zone minus the mid zone (called Hm zone) and the mL zone multiplied by the Hm zone (called Hm*mL zone). mL Zone will display the zones where the gas is presence while Hm * mL zones will show the presence of oil.

Abstrak :
Lapangan M merupakan lapangan gas yang terletak di Cekungan Sumatera Selatan dan sudah dikembangkan dengan pemboran 5 sumur pengembangan dari reservoar paparan karbonat Formasi Baturaja, dengan rata-rata produksi sebesar 4 MMCFPD per sumur. Berdasarkan hasil interpretasi seismik dan analog dengan lapangan minyak disebelah utara lapangan M, yaitu lapangan A, masih terdapat potensi reservoar minyak (oil rim) yang terletak downdip dari reservoar gas yaitu daerah yang belum dikembangkan di antara batas kontak gas dan minyak dengan batas kontak minyak dan air. Data produksi minyak sumur-sumur di lapangan A berkisar antara 100 - 800 BOPD per sumur. Hasil studi ini diharapkan dapat mengidentifikasi zona prospek minyak tersebut dan juga untuk pengembangan lebih lanjut zona gas. Menggunakan data seismik 3D dan data sumur, dilakukan evaluasi melalui metode dekomposisi spektral Continuous Wavelet Transform (CWT) data seismogram sintetik sumur dan data tras seismik yang melewati sumur, kemudian hasilnya disebarkan ke seluruh lapangan untuk mengidentifikasi penyebaran lateral keberadaan zona anomali frekuensi rendah. Hasil analisa dekomposisi spektral CWT pada data sumur dan data tras seismik yang ditunjukkan pada crossplot antara Amplitudo CWT dengan Frekuensi memperlihatkan korelasi yang cukup bagus. Sumur gas menunjukkan nilai amplitudo CWT paling tinggi pada frekuensi 10 ? 13 hz dan sumur minyak pada frekuensi 17 - 22 hz. Nilai amplitudo menurun pada frekuensi yang lebih tinggi. Pada sumur air, nilai amplitudo CWT selalu paling rendah pada frekuensi rendah hingga tinggi, sehingga dari crossplot tersebut dapat disimpulkan bahwa cut-off amplitudo zona air adalah pada 1,0+E09. Berdasarkan hasil analisis CWT dari data sumur ini, analisa dekomposisi spektral CWT kemudian disebarkan ke seluruh lapangan untuk bisa mengidentifikasi zona prospek. Selain itu, hasil crossplot antara nilai amplitudo CWT dengan nilai Saturasi air (Sw) pada zona reservoir memperlihatkan adanya hubungan yaitu nilai amplitudo CWT yang tinggi berkorelasi dengan nilai saturasi air yang rendah, begitupun sebaliknya.

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Field M is a gas field located in the South Sumatra Basin and has been developed by the drilling of five development wells from carbonate platform reservoir of Baturaja Formation, with average production of 4 MMCFPD per well. Based on the result of seismic interpretation and its analog to the oil field located to the north of field M, namely field A, there is still potential of oil reservoir (oil rim) located downdip from the gas reservoir The potential area is limited in the area that has not been developed between gas and oil contact and between oil and water contact. The production of oil wells in the field A ranges between 100-800 BOPD per well. The result of this study is expected to identify the oil zone and other prospects for further gas development. Based on 3D seismic data and well data, the evaluation was carried out using one of spectral decomposition methods, the Continuous Wavelet Transform (CWT). The analysis was done using both well synthetic seismogram data and seismic trace that crossing-through the wells. Then CWT was run on both data. Referring to the result of the analysis, CWT was distributed across the field to identify the presence of low-frequency zone. The results of the CWT analysis from well data and seismic trace data are shown on the crossplots between the amplitude and the frequency. They show a fairly good correlation. Gas zone shows the highest value of CWT amplitude at a frequency of 10-13 Hz and oil zone shows the highest value at a frequency of 17- 22 Hz. Amplitude values decreased in the higher frequencies. In the water zone, the value of the CWT amplitude is always lower in low to high frequencies. From the crossplot it can be concluded that the cut-off amplitude value for water zone is at 1.0 + E09. In any frequency, the CWT amplitudes below that value is nonhydrocarbon or water. The result of spectral decomposition that is based the above analysis and distributed throughout the field is able to identify zones of prospects. In addition to that, the crossplot between the CWT value and the water saturation (Sw) in each oil, gas and water zone shows a correlation. High CWT amplitudes correlate to low water saturation, and vice versa.

Abstrak :
[Lapangan FTM sebagai lapangan minyak dan gas bumi. Pada lapangan FTM terdapat dua reservoir gas dan reservoir minyak, yaitu formasi Minahaki dan Formasi Tomori. Penelitian yang dilakukan pada formasi Tomori dengan litologi batuan karbonat dan merupakan reservoir minyak yang berumur Miocene Akhir. Stuktur ini terbentuk oleh sesar mendatar (Trust fault) dengan sudut kecil yang berarah NE-SW. Identifikasi hidrokarbon pada studi ini didasarkan pada hasil metode dekomposisi spektral. Metode dekomposisi spektral berbasis ISA dan CWT digunakan untuk analisa anomali frekuensi rendah. Anomali frekuensi rendah berasosiasi adanya hidrokarbon. Analisa petrofisika pada lapangan FTM pada daerah hidrokarbon mempunyai porositas yang bagus dan saturasi air yang kecil. Hasil dari pemetaan zona prospek hidrokarbon dan analisa petrofisika ini diharapkan bisa dilakukan delineasi zona prospek untuk kepentingan survey seismik lebih lanjut dan acuan untuk proses pemboran.;FTM Field is one of the new fields as energy reserves in Indonesia as an oil and gas field. In the field there are two reservoirs FTM gas and oil reservoirs, namely the formation Minahaki and Tomori Formation. Research conducted on the formation lithology Tomori with carbonate rocks and an oil reservoir Late Miocene. This structure is formed by a horizontal fault (Trust fault) with a small angle of the NE - SW trending. Hydrocarbon determination using spectral decomposition method, based spectral decomposition method is used for analysis ISA and CWT low frequency anomaly. Low frequency anomaly associated hydrocarbon indicator. Petrophysical analysis FTM field have good porosity and water saturation small on hydrocarbon area. Results of mapping zones of hydrocarbon prospects and petro physical analysis is expected to be used for the benefit of the prospect delineation zone further seismic surveys and drilling of reference for the process.;FTM Field is one of the new fields as energy reserves in Indonesia as an oil and gas field. In the field there are two reservoirs FTM gas and oil reservoirs, namely the formation Minahaki and Tomori Formation. Research conducted on the formation lithology Tomori with carbonate rocks and an oil reservoir Late Miocene. This structure is formed by a horizontal fault (Trust fault) with a small angle of the NE - SW trending. Hydrocarbon determination using spectral decomposition method, based spectral decomposition method is used for analysis ISA and CWT low frequency anomaly. Low frequency anomaly associated hydrocarbon indicator. Petrophysical analysis FTM field have good porosity and water saturation small on hydrocarbon area. Results of mapping zones of hydrocarbon prospects and petro physical analysis is expected to be used for the benefit of the prospect delineation zone further seismic surveys and drilling of reference for the process.;FTM Field is one of the new fields as energy reserves in Indonesia as an oil and gas field. In the field there are two reservoirs FTM gas and oil reservoirs, namely the formation Minahaki and Tomori Formation. Research conducted on the formation lithology Tomori with carbonate rocks and an oil reservoir Late Miocene. This structure is formed by a horizontal fault (Trust fault) with a small angle of the NE - SW trending. Hydrocarbon determination using spectral decomposition method, based spectral decomposition method is used for analysis ISA and CWT low frequency anomaly. Low frequency anomaly associated hydrocarbon indicator. Petrophysical analysis FTM field have good porosity and water saturation small on hydrocarbon area. Results of mapping zones of hydrocarbon prospects and petro physical analysis is expected to be used for the benefit of the prospect delineation zone further seismic surveys and drilling of reference for the process.;FTM Field is one of the new fields as energy reserves in Indonesia as an oil and gas field. In the field there are two reservoirs FTM gas and oil reservoirs, namely the formation Minahaki and Tomori Formation. Research conducted on the formation lithology Tomori with carbonate rocks and an oil reservoir Late Miocene. This structure is formed by a horizontal fault (Trust fault) with a small angle of the NE - SW trending. Hydrocarbon determination using spectral decomposition method, based spectral decomposition method is used for analysis ISA and CWT low frequency anomaly. Low frequency anomaly associated hydrocarbon indicator. Petrophysical analysis FTM field have good porosity and water saturation small on hydrocarbon area. Results of mapping zones of hydrocarbon prospects and petro physical analysis is expected to be used for the benefit of the prospect delineation zone further seismic surveys and drilling of reference for the process.;FTM Field is one of the new fields as energy reserves in Indonesia as an oil and gas field. In the field there are two reservoirs FTM gas and oil reservoirs, namely the formation Minahaki and Tomori Formation. Research conducted on the formation lithology Tomori with carbonate rocks and an oil reservoir Late Miocene. This structure is formed by a horizontal fault (Trust fault) with a small angle of the NE - SW trending. Hydrocarbon determination using spectral decomposition method, based spectral decomposition method is used for analysis ISA and CWT low frequency anomaly. Low frequency anomaly associated hydrocarbon indicator. Petrophysical analysis FTM field have good porosity and water saturation small on hydrocarbon area. Results of mapping zones of hydrocarbon prospects and petro physical analysis is expected to be used for the benefit of the prospect delineation zone further seismic surveys and drilling of reference for the process., FTM Field is one of the new fields as energy reserves in Indonesia as an oil and gas field. In the field there are two reservoirs FTM gas and oil reservoirs, namely the formation Minahaki and Tomori Formation. Research conducted on the formation lithology Tomori with carbonate rocks and an oil reservoir Late Miocene. This structure is formed by a horizontal fault (Trust fault) with a small angle of the NE - SW trending. Hydrocarbon determination using spectral decomposition method, based spectral decomposition method is used for analysis ISA and CWT low frequency anomaly. Low frequency anomaly associated hydrocarbon indicator. Petrophysical analysis FTM field have good porosity and water saturation small on hydrocarbon area. Results of mapping zones of hydrocarbon prospects and petro physical analysis is expected to be used for the benefit of the prospect delineation zone further seismic surveys and drilling of reference for the process.]

Abstrak :
[Lapangan FTM sebagai lapangan minyak dan gas bumi. Pada lapangan FTM terdapat dua reservoir gas dan reservoir minyak, yaitu formasi Minahaki dan Formasi Tomori. Penelitian yang dilakukan pada formasi Tomori dengan litologi batuan karbonat dan merupakan reservoir minyak yang berumur Miocene Akhir. Stuktur ini terbentuk oleh sesar mendatar (Trust fault) dengan sudut kecil yang berarah NE-SW. Identifikasi hidrokarbon pada studi ini didasarkan pada hasil metode dekomposisi spektral. Metode dekomposisi spektral berbasis ISA dan CWT digunakan untuk analisa anomali frekuensi rendah. Anomali frekuensi rendah berasosiasi adanya hidrokarbon. Analisa petrofisika pada lapangan FTM pada daerah hidrokarbon mempunyai porositas yang bagus dan saturasi air yang kecil. Hasil dari pemetaan zona prospek hidrokarbon dan analisa petrofisika ini diharapkan bisa dilakukan delineasi zona prospek untuk kepentingan survey seismik lebih lanjut dan acuan untuk proses pemboran. ......FTM Field is one of the new fields as energy reserves in Indonesia as an oil and gas field. In the field there are two reservoirs FTM gas and oil reservoirs, namely the formation Minahaki and Tomori Formation. Research conducted on the formation lithology Tomori with carbonate rocks and an oil reservoir Late Miocene. This structure is formed by a horizontal fault (Trust fault) with a small angle of the NE - SW trending. Hydrocarbon determination using spectral decomposition method, based spectral decomposition method is used for analysis ISA and CWT low frequency anomaly. Low frequency anomaly associated hydrocarbon indicator. Petrophysical analysis FTM field have good porosity and water saturation small on hydrocarbon area. Results of mapping zones of hydrocarbon prospects and petro physical analysis is expected to be used for the benefit of the prospect delineation zone further seismic surveys and drilling of reference for the process;FTM Field is one of the new fields as energy reserves in Indonesia as an oil and gas field. In the field there are two reservoirs FTM gas and oil reservoirs, namely the formation Minahaki and Tomori Formation. Research conducted on the formation lithology Tomori with carbonate rocks and an oil reservoir Late Miocene. This structure is formed by a horizontal fault (Trust fault) with a small angle of the NE - SW trending. Hydrocarbon determination using spectral decomposition method, based spectral decomposition method is used for analysis ISA and CWT low frequency anomaly. Low frequency anomaly associated hydrocarbon indicator. Petrophysical analysis FTM field have good porosity and water saturation small on hydrocarbon area. Results of mapping zones of hydrocarbon prospects and petro physical analysis is expected to be used for the benefit of the prospect delineation zone further seismic surveys and drilling of reference for the process., FTM Field is one of the new fields as energy reserves in Indonesia as an oil and gas field. In the field there are two reservoirs FTM gas and oil reservoirs, namely the formation Minahaki and Tomori Formation. Research conducted on the formation lithology Tomori with carbonate rocks and an oil reservoir Late Miocene. This structure is formed by a horizontal fault (Trust fault) with a small angle of the NE - SW trending. Hydrocarbon determination using spectral decomposition method, based spectral decomposition method is used for analysis ISA and CWT low frequency anomaly. Low frequency anomaly associated hydrocarbon indicator. Petrophysical analysis FTM field have good porosity and water saturation small on hydrocarbon area. Results of mapping zones of hydrocarbon prospects and petro physical analysis is expected to be used for the benefit of the prospect delineation zone further seismic surveys and drilling of reference for the process]

Abstrak :
Lapangan XYZ adalah lapangan gas yang berada di Selat Makasar Kalimantan Timur. Lapangan ini terletak di bagian timur dari laut dalam Delta Mahakam dan kedalaman rata-rata air laut di daerah ini kurang lebih 6000 feet. Reservoir di lapangan ini dipercaya sebagai endapan turbidite laut dalam, dan dikenal sebagai "deep water channelized system" yang berumur antara Pliosen bawah - Miosen Atas. Oleh karena itu reservoir di daerah ini memiliki kuantitas dan kualitas yang sangat bervariasi. Dalam penelitian ini dipilih metoda dekomposisi spektral yang hasilnya diharapkan akan dapat digunakan dalam mendeliniasi, dan analisa facies reservoir dengan pendekatan model yang telah ada sebelumnya dan telah dilakukan oleh Slatt 2006. Sementara ekstraksi atribut RMS dilakukan untuk melihat distribusi kandidat reservoir sekaligus menjadi pembanding dan pendukung informasi yang didapat dari metoda dekomposisi spektral. Hasil penelitian ini pada akhirnya akan sangat berguna bagi perhitungan cadangan rinci, yang akan sangat tergantung pada geometri dan kualitas reservoir. Selain itu juga akan berguna bagi perencanaan produksi pada fase eksploitasi. Dari hasil penelitian ini , didapatkan tiga facies reservoir dan hubungan korelasi yang kuat antara metode dekomposisi spektral dengan ekstraksi atribut RMS tersebut. Dengan ektraksi atribut RMS dapat dilihat distribusi reservoir secara umum berdasarkan tingginya nilai atribut RMS. Sementara untuk deliniasi reservoir secara lebih rinci diperoleh dari hasil analisis dekomposisi spektral. Universitas Indonesia. ......The XYZ Field is one of the gas fields located in Makasar Strait-East Kalimantan. It lies in the Eastern part of deepwater Mahakam Delta. The average water depth in the area is about 6000 feet. The reservoir of this field is believed to be the product of deepwater turbidite sedimentation as "deep water channelized system" of Lower Pliocene to Upper Miocene in age. As a consequence reservoir of this area has great variations in quality and quantity. In this research the spectral decomposition method was chosen and expected to be used in reservoir deliniation and facies analysis based on previous model approaches Slatt, 2006. While RMS attribute extraction carried out in order to analyze the distribution of reservoir candidate as well as the benchmark and supporting information for the spectral decomposition method. The result of this study will be very important for detail reserved calculations, which will be very rely on to the reservoir geometry and quality. Moreover it will be very useful for the production planning at the exploitation phase. From this study, it is concluded there are 3 (three) main facies of reservoir in the area, and there is a strong correlation between result of spectral decomposition and RMS attribute. From the RMS attribute extraction, the author found a general reservoir distribution based on the height of RMS value. Meanwhile for more detail reservoir deliniation, it has been achieved from the spectral decomposition analysis.

Abstrak :
Fenomena low frequency shadows merupakan fenomena unik yang terkadang dijumpai dalam analisis data seismik. Keberadaan fenomena ini terutama terkait dengan keberadaan reservoar hidrokarbon sehingga kemudian diperhitungkan sebagai direct hydrocarbon indicator. Low frequency shadows hanya dapat terlihat pada kisaran frekuensi tertentu, sehingga tidak akan terlihat langsung dari data seismik yang bersifat broadband. Time-frequency decomposition atau yang lebih umum dikenal sebagai spectral decomposition memberikan informasi variasi komponen frekuensi dari sebuah sinyal di sepanjang waktu. S-Transform merupakan salah satu metode spectral decomposition yang dapat digunakan untuk menganalisis sinyal non-stasioner. Metode ini merupakan pengembangan ide dari metode Continuous Wavelet Transform (CWT) yang didasarkan pada lokalisasi window Gaussian yang bergeser pada skala tertentu. S-Transform mampu memberikan resolusi frekuensi dari setiap time sample dengan tetap berhubungan dengan spektrum Fourier. Pada penelitian ini, spectral decomposition berbasis S-Transform digunakan untuk mengidentifikasi keberadaan low frequency shadows dari sebuah data poststack seismik 3D. Berdasarkan hasil analisis terbukti bahwa fenomena low frequency shadows memang berkaitan erat dengan keberadaan reservoar hidrokarbon. Selain itu, dengan melihat sebaran konten frekuensi dari data seismik secara lateral, terlihat adanya area yang berpotensi mengandung hidrokarbon karena memiliki low frequency shadows.

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Low frequency shadows is a unique feature which can be found in seismic data analysis. The existence of this anomaly is closely related to the existence of hydrocarbon reservoir, so it is usually considered as a direct hydrocarbon indicator. Low frequency shadows only visible at certain frequency (low frequency), so it will not be visible directly from a broadband seismic data. Time-frequency decomposition or which is generally known as spectral decomposition gives information about the variation of frequency components from a signal through time. S-Transform is one of the spectral decomposition methods which can be used to analyze non-stationer signal. This method is an extension ideas of Continuous Wavelet Transform (CWT) which is based on a moving and scalable Gaussian window. S-Transform can provide frequency resolution for each time sample, and still maintain a connection with Fourier spectrum. In this paper, S-Transform spectral decomposition is used to identify the existence of low frequency shadows from a 3D post-stack seismic data. Based on the analysis result, it is proven that the existence of low frequency shadows indeed related to the existence of hydrocarbon reservoir. By analyzing the distribution of the frequency map laterally, it is shown that there is an area, which potentially contains hydrocarbon as indicated by low frequency shadows anomaly.

Abstrak :
Penelitian ini terletak di lapangan Danish North Sea, tepatnya di sebelah barat dari Denmark. Reservoar Karbonat pada lapangan ini merupakan platform karbonat, dimana litologinya berupa chalk pada formasi ekofisk di kedalaman 1850 m. Metoda Atribut Dekomposisi Spektral sangat baik untuk mengidentifikasi hidrokarbon berdasarkan parameter frekuensi. Pada penelitian ini menggunakan CWT (Continuous Wavelet Transform) dengan menggunakan wavelet Mexican Hat sebagai wavelet input. Pada interpretasi lanjut menganalisis grafik dari time - frekuensi spektrum, dimana grafik ini menunjukan 2 karakteristik reservoar konten (reservoar minyak dan reservoar air). Frekuensi dominan dari minyak yang ditunjukan pada grafik sebesar 20 Hz. Setelah itu ditentukan penyebaran reservoar dari konten minyak tersebut. Berdasarkan hasil analisa dekomposisi spektral menunjukan persebaran hidrokarbon pada reservoar chalk formasi ekofisk berada pada bagian selatan, timur laut, dan barat laut lapangan danish north sea merupakan zona prospek.

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This research is located in Danish North Sea Field, the west side of Denmark. Carbonat Reservoirs in the field were formed in platform carbonate type which the lithology was the chalk layer at Ekofisk formation around 1850 m. The spectral decomposition method is very good tool to identify the hydrocarbon prospecting based on frequency parameters. In this research, the author using CWT (Continuous Wavelet Transform) with respect to Mexican Hat wavelet type as wavelet input the relation time - frequency spectrum. The result showed two kind reservoirs prospecting, hidrocarbon and water reservoir. From hydrocarbon reservoir, it was found the frequency dominant around 20 Hz, whereas the water reservoir was 23 Hz. Then, we applied CWT by the frequency dominant 20 Hz to seismic horizon target in this area. Based spectral decomposition analyzed, we cofirmed the hydrocarbon prospecting originated from chalk layer in Ekofisk formation. The prospect time was positioned in the south side and north-east side directions.

Abstrak :
Lokasi penelitian yang terletak di cekungan Jawa Timur (East Java Basin) adalah daerah yang dilalui oleh zona patahan Rembang-Madura-Kangean-Sakala ( RMKS Fault Zone) yang merupakan zona dengan deformasi sesar yang kuat. Berdasarkan data sumur ekplorasi, Zona target berada pada formasi Ngimbang Karbonat, didominasi oleh batuan gamping dan terletak pada kedalaman 2012 m sampai 2470 m. Dari hasil studi gas analysis sebelumnya, formasi Ngimbang Karbonat berpotensi sebagai reservoar hidrokarbon dengan kenampakan gas show yang cukup tinggi pada formasi tersebut. Hal ini didukung juga oleh nilai log resistivitas yang tinggi yang mungkin berasosiasi dengan keberadaan hidrokarbon. Pada penelitian ini, inversi impedansi akustik menggunakan metoda Sparse Spike digunakan untuk menunjukkan keberadaan reservoar pada zona target. Hasil dari inversi ini menunjukkan terdapat satu lapisan pada formasi Ngimbang Karbonat yang mempunyai nilai impedansi akustik yang relatif lebih rendah dari bodi sekitar nya yaitu 6600 sampai 7700 (m/s).(g/cc). Pada penelitian ini, penulis menkonversi nilai impedansi akustik menjadi parameter porositas dan didapatkan nilai porositas zona target berkisar 8 - 10 %. Selanjutnya metoda dekomposisi spektral dengan algoritma CWT digunakan untuk melihat saturasi fluida dari zona target. Hasil dari metoda CWT ini menunjukkan adanya fenomena Low Shadow Frequency pada frekuensi 8 Hz. Fenomena ini diduga berasosiasi dengan keberadaan hidrokarbon yang mensaturasi batuan pada zona target. Hal ini didukung dengan hasil inversi sebelumnya bahwa dengan menggunakan kombinasi kedua metoda tersebut, diduga bahwa terdapat akumulasi hidrokarbon jenis gas pada zona target penelitian.

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Location of research area is located in East Java Basin which is passed by a big fault zone named Rembang - Madura - Kangean - Sakala (RMKS) fault zone. The target area is a zone with strong fault deformation. Based on well exploration data, the target zone is Ngimbang Karbonat Formation which is dominated by Carbonate limestone and at the depth of 2012 m until 2470 m. Gas Analysis study shows that the Ngimbang Karbonat Formation is highly potential for becoming a reservoar rock which shows highly gas shows on that formation. This is also supported by high resistivity value from log data that maybe associated with hydrocarbon existence.In this research, Acoustic Impedance with Sparse Spike algorithm is used to show the existence of reservoir on the target zone. The result of this inversion shows that there is one body of rock on Ngimbang Karbonat fm that has low acoustic impedance value 6600 – 7700 (m/s).(g/cc) compared to the other body. I convert this acoustic impedance value into porosity parameter and get a range of value from 8 - 10 %. Finally, spectral decomposition method based on CWT algorithm is used to see the fluid saturation on the target zone. The result of this method show that there is a Low Shadow Frequency phenomenon at frequency 8 Hz. This phenomenon may be associated with the existence of hydrocarbon that saturate the rocks on the target zone. It is supported by the result of the inversion before that with the combination of both method, we can conclude that the target zone is highly potential to become a reservoir rock with accumulation of hydrocarbon on that zone.

Abstrak :
Lapangan Talavera seluas 230km2 adalah lapangan migas yang berada di Cekungan Sumatera Utara yang merupakan salah satu cekungan mature di Indonesia. Lapangan ini diduga memiliki fitur stratigrafi berupa chanel dan delta dengan perlapisan batu pasir yang tipis sehingga tidak dapat terdeteksi dalam peta seismik konvensional. Dalam penelitian ini dipilih atribut seismik dekomposisi spektral berbasis Continuous Wavelet Transform (CWT) yang dapat mengekstrak informasi frekuensi dari peta seismik fungsi waktu menjadi peta fungsi waktu-frekuensi. Hasilnya diharapkan akan dapat digunakan untuk mendelineasi fitur stratigrafi dan mengetahui penyebaran lapisan batu pasir (batuan reservoar). Sementara atribut RMS amplitude digunakan untuk melihat distribusi kandidat reservoar sekaligus menjadi data pembanding dan pendukung informasi yang didapat dari atribut dekomposisi spektral. Pada akhirnya, hasil penellitian ini akan sangat berguna bagi perhitungan cadangan rinci, yang akan sangat tergantung pada geometri dan kualitas reservoar. Selain itu, juga akan berguna bagi perencanaan produksi pada fase eksploitasi. Dari hasil penelitian ini didapatkan tiga fasies reservoar dan hubungan korelasi yang kuat antara metode dekomposisi spektral dengan ekstraksi atribut RMS amplitude. Dengan atribut RMS amplitude dapat dilihat distribusi reservoar berdasarkan tingginya nilai amplitudo. Sementara untuk delineasi batu pasir secara lebih rinci diperoleh dari hasil analisa dekomposisi spektral.

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Talavera is a 230km2 area of the oil and gas field located in the North Sumatra Basin, which is one mature basins in Indonesia. This field has allegedly stratigraphic features such as channels and delta sandstone with thin bedding that can not be detected in conventional seismic map. In this study, seismic attribute spectral decomposition based on Continuous Wavelet Transform ( CWT ) is selected to extract the frequency information from the seismic map time domain becomes a seismic map time - frequency domain. The results are expected to be used to delineate the stratigraphic and geographic distribution of feature layers of sandstone (reservoir rock) . While the RMS amplitude attribute is used to look at the distribution of the reservoir as well as a candidate benchmark data and supporting information obtained from spectral decomposition attributes. In the end, this study results will be useful for a detailed calculation of reserves, which will depend on the geometry and quality of the reservoir. In addition, it will also be useful for the planning of production in the exploitation phase. From the results of this study, the three reservoir facies and a strong correlation between the spectral decomposition method with RMS amplitude attribute extraction are detected. With RMS amplitude attribute can be seen by the high value of reservoir distribution amplitude . As for the delineation of sandstone in more detail the results obtained from the spectral decomposition analysis.

Abstrak :
Pemetaan sebaran reservoar dengan menggunakan dekomposisi spektral dan Amplitude Versus Offset AVO telah dilakukan di Sub-Cekungan Jambi. Sub-Cekungan Jambi adalah bagian dari Cekungan Sumatera Selatan yang merupakan cekungan belakang busur berumur Tersier yang terbentuk sebagai akibat tumbukan antara India plate dan Sundaland. Reservoar utama dalam penelitian ini adalah batupasir Horizon M dan N, yang termasuk dalam Formasi Air Benakat Bawah FABB. Formasi ini memiliki umur Miosen Tengah dimana terbentuk perselingan batulempung dengan batupasir dan batulanau. Tujuan dari penelitian ini adalah untuk menyelidiki sebaran reservoar menggunakan analisis Dekomposisi Spektral dan AVO pada horizon M dan N. Metode yang digunakan adalah Continous Wavelet Transform CWT dengan menggunakan wavelet Morlet. Dalam penelitian ini dilakukan analisis zona frekuensi rendah dimana anomali amplitudo diamati pada frekuensi rendah 15 Hz dan kemudian dibandingkan dengan amplitudo pada frekuensi pertengahan 25 Hz dan frekuensi tinggi 40 Hz. Anomali yang diamati adalah nilai amplitudo terlihat pada frekuensi rendah dan menghilang pada frekuensi tinggi. Analisis AVO digunakan untuk memverikasi hasil analisis dekomposisi spektral dengan menggunakan atribut intercept dan gradien. Hasil dari penggabungan kedua metode ini berhasil menunjukkan bahwa keberadaan reservoar hidrokarbon berada disekitar sumur M-07.

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The reservoir distribution map with spectral decomposition method and Amplitude Versus Offset AVO has been done in Jambi Sub Basin. Jambi Sub basin is a part of South Sumatera Basin which is a back arc tertiary basin formed as a result of the collision between the Indian Plate and the Sundaland. The main reservoir of this structure is a sandstone Horizon M and N, which are included into the Lower Air Benakat Formation LABF. This formation has Middle Miocene age where formed claystone intersections with sandstone and siltstone. This aim of the study is to investigate the distribution of reservoir hydrocarbon using Spectral Decomposition and AVO at horizon M and N. The method used is Continuous Wavelet Transform CWT and using morlet wavelet as the input of processing. In this study, we perform low frequency shadow zone analysis in which the amplitude anomaly at a low frequency of 15 Hz was observed and we then compare it to the amplitude at the mid 25 Hz and the high frequency 40 Hz . The appearance of the amplitude anomaly at a low frequency was disappeared at high frequency, this anomaly disappears. The AVO analysis is used to verify the results of the spectral decomposition analysis using the intercept and gradient attributes. The result of combining these two methods succeeds to show that the hydrocarbon reservoir is located around the well M 07.