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"West Natuna Barat merupakan cekungan yang memiliki lingkungan fluvial dengan reservoir berupa bed-sand berselingan dengan shale dan shaly-sand. Metode inversi dilakukan dengan Seismic Colored Inversion yang akan memberikan hasil yang kuat untuk melihat fitur geologi berupa kanal pasir menerus yang memiliki nilai Impedansi Akustik rendah pada zona-zona yang menarik. Pengirisan dilakukan pada horizon A1, saluran pasir dengan nilai AI berkisar antara 12.000 hingga 15.500 ((ft/s)*(g/cc) tersebar di tengah zona penelitian ke arah timur. , alur pasir dengan AI berkisar antara 16.000 sampai 17.800 ((ft/s)*(g/cc)) tersebar di daerah tengah zona penelitian sekitar U1 sampai U3, juga terlihat di timur laut zona penelitian. Pada hasil slicing horizon C1, ditemukan saluran pasir dengan nilai AI berkisar antara 18.000 sampai dengan 19.000 ((ft/s)*(g/cc)) di daerah tengah zona penelitian dekat sumur U1 sampai U3.

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The West Natuna Basin is a basin that has a fluvial environment with a reservoir in the form of bed-sand alternating with shale and shaly-sand. The inversion method is carried out with Seismic Colored Inversion which will give strong results to see geological features in the form of continuous sand canals that have low Acoustic Impedance values ​​in interesting zones. The slicing was carried out on the A1 horizon, a sand channel with AI values ​​ranging from 12,000 to 15,500 ((ft/s)*(g/cc) spread in the center of the study zone to the east. , sand grooves with AI ranging from 16,000 to 17,800 ((ft) /s)*(g/cc)) is spread in the central area of ​​the study zone around U1 to U3, also seen in the northeast of the study zone. In the results of the slicing horizon C1, sand channels were found with AI values ​​ranging from 18,000 to 19,000 ((ft /s)*(g/cc)) in the center of the study zone near wells U1 to U3."

"Kabupaten Natuna merupakan salah satu daerah penghasil minyak dan gas bumi terbesar di Indonesia. Lapangan “X” merupakan lapangan yang terletak di Cekungan Natuna Barat dan potensi pada lapangan tersebut perlu terus dilakukan evaluasi dan optimalisasi produksi guna memenuhi kebutuhan energi dalam negeri di masa yang akan datang. Metode seismik refleksi merupakan salah satu metode geofisika yang seringkali digunakan untuk melakukan eksplorasi dan pengembangan hidrokarbon. Pada penelitian ini digunakan metode inversi impedansi akustik dan analisis atribut seismik untuk melakukan identifikasi distribusi reservoir pada daerah penelitian. Penelitian dilakukan pada zona target yang terletak di Formasi Upper Gabus, dimana Formasi Upper Gabus dapat dikatakan sebagai reservoir rock yang cukup baik karena memiliki sifat porositas yang baik. Berdasarkan analisis atribut seismik variance, dapat diinterpretasikan keberadaan sesar normal dengan orientasi NW – SE dan sesar naik dengan orientasi SW – NE yang berpotensi sebagai trap struktural pada Lapangan X. Berdasarkan peta atribut amplitudo RMS dan atribut envelope pada zona target, zona prospek reservoir berasosiasi dengan nilai amplitudo RMS tinggi yang berada pada rentang 7000 - 9500 mm/s dan nilai envelope tinggi yang berada pada rentang 8500 – 14000 mm/s. Berdasarkan peta atribut spectral decomposition dan atribut amplitudo RMS, dapat digambarkan pola lingkungan pengendapan yang diasumsikan arah sedimentasi berasal dari barat daya menuju timur laut (SW – NE) dengan sistem pengendapan berupa fluvial channel. Pada penelitian ini didapatkan estimasi nilai impedansi akustik batupasir pada Lapangan X berkisar antara 17.000 hingga 23.000 (ft/s)*(g/cc) dan dapat diperkirakan tren persebaran berasal dari barat daya menuju timur laut (SW – NE). Berdasarkan penelitian ini, persebaran zona prospek reservoir terletak pada daerah tinggian dalam domain waktu yang berkisar antara -1300 hingga -1200 ms, dimana daerah tinggian tersebut diasumsikan berasosiasi dengan keberadaan antiklin.

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Natuna Regency is one of the largest oil and gas producing regions in Indonesia. Field "X" is a field located in the West Natuna Basin and the potential in this field needs to be continuously evaluated and optimized for production to fulfil energy needs in the future. The seismic reflection method is a geophysical method that is often used to explore and develop hydrocarbons. In this study, the acoustic impedance inversion method and seismic attribute analysis were used to identify the reservoir distribution in the study area. The research was conducted on the target zone which is located in the Upper Gabus Formation, where the Upper Gabus Formation can be said to be a fairly good reservoir rock because it has good porosity properties. Based on the analysis of variance attributes, it can be interpreted that there are normal faults with NW – SE orientation and reverse faults with SW – NE orientation that have the potential to act as structural traps in Field “X”. Based on the map of the RMS amplitude attribute and envelope attribute in the target zone, the reservoir prospect zone is associated with high RMS amplitude values in the range of 7000 - 9500 mm/s and high envelope values in the range of 8500 – 14000 mm/s. Based on the spectral decomposition attribute map and the RMS amplitude attribute, it can be described the pattern of depositional environment which can be assumed the direction of sedimentation originates from the southwest to the northeast (SW - NE) with a fluvial channel depositional system. In this study, the estimated acoustic impedance values of the sandstones in Field X ranged from 17,000 to 23,000 (ft/s)*(g/cc) and it can be estimated that the distribution trend originates from southwest to northeast (SW – NE). Based on this study, the distribution of the reservoir prospect zone located in the high areas in the time domain ranging from -1300 to -1200 ms, where the high areas are assumed to be associated with the presence of anticline."

"ABSTRACTUG Massive formation is the main reservoir of Javaz field, oil and gasproducing field, situated in West Natuna Basin. The use of acoustic impedance (PImpedance)only to characterize reservoir hydrocarbon in this field will lead us intolarge uncertainty. Therefore, to overcome that issue, Seismic Simultaneous Inversionmethod is used at Javaz field within UG Massive formation interval. This method isapplied as an alternative method to predict the pore gas (Lambda-Rho) and porositydistribution, using partial post stack 3D seismic data which are invertedsimultaneously; then Javaz-4 well data which will be used as a reference well forpredicting reservoir properties in other wells at Javaz field.Seismic Simultaneous Inversion method resulted Javaz-3 well has similarreservoir properties as studied in Javaz-4 well. However, Javaz-1A and Javaz-2showed different result caused by large uncertainty in seismic resolution (poor qualityseismic data). Porosity and pore gas prediction suggested around 20 to 30 percent and13 to 18 GPa*g/cc respectively, throughout the field. Hence, this method could beused as an alternative to predict UG Massive reservoir properties in Javaz field awayfrom the wells, and it could be applied to the same field with large uncertainty.

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ABSTRAKFormasi UG Massive merupakan reservoar utama pada lapangan Javaz,lapangan ini memproduksi minyak dan gas dan berada pada cekungan Natuna Barat.Study yang dilakukan untuk mengkarakterisasi reservoir hydrocarbon pada lapanganini jika hanya menggunakan akustik impedance (P-Impedance) saja akanmenimbulkan ketidakpastian, untuk mengatasi hal ini maka metode Seismicsimultaneous inversion digunakan pada lapangan Javaz dengan target formasi UGMassive. Metode ini digunakan sebagai alternative untuk memprediksi sebaran poregas (Lambd-Rho) dan porositas, dengan menggunakan partial post stack 3D seismicdata yang di inversikan secara bersamaan dan satu sumur (Javaz-4) data yangdigunakan sebagai kontrol untuk kemudian dijadikan acuan dalam memprediksikarakter reservoir para area sumur lainnya.Dengan menggunakan metode Seismic simultaneous inversion ini, makadidapatkan hasil prediksi karakter reservoir pada sumur Javaz-3 yang memilikikarakter mendekati sumur Javaz-4 pada formasi utama, namun tidak demikian untuksumur Javaz-2 dan Javaz-1A. Untuk perkiraan sebaran porositas maupun pore gasdidapatkan hasil yang cukup baik, dengan nilai porositas berkisar antara 20% hingga30% dan pore gas (Lambda-Rho) yang berkisar antara 13 (GPa*g/cc) hingga 18(GPa*g/cc). Dari hasil study ini maka dapat disimpulkan bahwa metode ini dapatdigunakan sebagai alternative untuk memprediksi karakter reservoar pada formasiUG Massive."

"Lapangan Kale terletak pada Sub Cekungan Jambi, Cekungan Sumatera Selatan dimana lapangan ini berada pada Blok yang aktif menghasilkan minyak dan gas bumi. Keekonomian atau nilai dari suatu lapangan minyak gas sangat penting dalam rangka pengembangan lapangan tersebut. Sehingga studi integrasi antara geologi dan geofisika mengenai karakterisasi reservoar pada lapangan ini sangat diperlukan. Angka yang didapat dalam hal cadangan akan sangat penting bagi seorang reservoir engineer dalam menentukan keekonomian lapangan tersebut. Berbekal data survey seismik 3D dan 4 sumur eksplorasi studi integrasi geologi dan geofisika ini dijalankan. 3 fase studi utama, yaitu analisa petrofisika, dimana kita dapat mengetahui sifat fisik dari batuan reservoar pada tiap sumurnya di lapangan Kale pembuatan impedansi akustik, dimana didahului dengan analisa rock physic pada data sumur, terlihat jelas bahwa impedansi akustik pada data sumur dapat membedakan 3 jenis litologi yang berkembang pada reservoar sand-A formasi LTAF. Pemodelan geologi, dimana impedansi akustik dan juga data dari analisa petrofisika dipakai sebagai input dalam pemodelan geologi ini. Output dari studi ini akan menghasilkan beberapa peta sebaran reservoar, mulai dari peta sebaran fasies dimana berdasarkan data core sumur Kale-2 reservoar sand-A formasi LTAF diendapkan pada lingkungan transisi/ delta. Peta sebaran porositas, dimana kontrol fasies dipakai dalam mempopulasikan porositas pada reservoar sand- A lapangan Kale. Peta sebaran permeabilitas, di buat berdasarkan persamaan antara porositas dan permeabilitas yang ada pada data core, sehingga nilai permeabilitas pada studi ini didapat dari transformasi porositas- permeabilitas dengan menggunakan persamaan tersebut.

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Kale is Field located at Jambi Sub Basin, South Sumatera Basin, which is being a part of one of active blocks in Indonesia. Field economic value is the most important thing in order to develop oil and gas field. Integrated geology and geophysics study for reservoir characterization in this field is urgently needed. For reservoir engineer, reserve estimation from geologist will be used to run the economic evaluation in this field. 3D Seismic data and 4 four exploration wells are used in this integrated G G study. Three primary phases is carried out in order to run this study. Petrophysical analysis in each well in Kale field will be evaluated to have all the petrophysical value in A sand reservoir Acoustic impedance cube generated base on rock physic analysis which is acoustic impedance can divided A sand reservoir into 3 three lithology Geological modeling generated with acoustic impedance cube and petrophysical data as the input. The result of this study is presented in reservoir distribution map, such as facies which is controlled by core data from Kale 2 well that showing this reservoir deposited at delta environment. Porosity distribution map generated with facies distribution control. Porosity permeability plot at Kale 2 well have a good equation will be used to transform porosity value to permeability value."

"Perubahan sifat-sifat batuan seperti porositas, densitas, saturasi dan lain-lain terefleksikan oleh perubahan impedansi seismik. Seperti diketahui, inversi seismik memungkinkan kita untuk mencari korelasinya pada domain impedansi, yang secara unik sering mencirikan perubahan sifat-sifat batuan. Namun demikian, analisa dari seismic inversi full stack gelombang-P membawa kita pada kesimpulan yang membingungkan pada banyak situasi explorasi.Dengan melakukan inversi simultan, kita diarahkan pada interpretasi hasil inversi yang lebih pasti dimana kita dapat mengestimasi densitas, impedansi P dan S yang memberikan respon yang cukup berbeda dalam memisahkan pengaruh lithology dan fluida. Dengan menggunakan konsep matematika inversi AVO, inversi simultan menggunakan data partial angle stack yang kemudian diinversikan secara bersamaan menggunakan wavelet yang di extract dari setiap offset.Kemudian dengan mengkombinasikan parameter-parameter ini dengan teknik analisa rock physics yang dapat digunakan sebagai alat untuk memprediksi distribusi lithology, porositas dan saturasi.Kemudian parameter-parameter ini juga dapat ditransformasikan menjadi Lambda-Rho yang dapat digunakan sebagai indikator kandungan fluida di pori batuan. Akhirnya dengan menganalisa peta distribusi sifat batuan yang di overlay dengan peta struktur dan sumur produksi, kita dapat mengidentifikasi area potensial untuk strategi pengembangan lebih lanjut untuk mengoptimalkan pengurasan hidrokarbon pada area studi.

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The change of lateral rock properties such as porosity, density, fluid saturation etc are reflected in seismic impedance changing. It is known widely that seismic inversion allows us for correlation investigation in the impedance domain which often highlights uniquely the change of rock properties. However the analysis of the early P-wave fullstack seismic inversion data alone can lead to ambiguous conclusions in many exploration situations.

Answering this problem, performing simultaneous inversion will bring us to a less ambiguous interpretation of our inversion results in which we are able to estimate Density, P and S-impedance which have sufficiently different response to discriminate fluid and lithology effects. Utilizing the mathematical concept of AVO inversion, simultaneous inversion use partial angle stack data which can be inverted simultaneously using wavelet extracted from each offset.

Later, these parameters combined with rock physics technique analysis can be used as a tool to predict sand, porosity and saturation distribution. Also, they can be transformed to Lambda-Rho (λρ) that is used for pore fluid content indicator. Finally by analyzing the rock properties distribution map overlaid by structure map and producer well, we can identify the potential area for further development strategy to optimize the hydrocarbon recovery of the study area."

"Konsumsi dan kebutuhan minyak dan gas bumi di Indonesia semakin tahun semakin meningkat sayangnya produksi minyak dan gas di Indonesia belum bisa mengimbangi permintaan yang terus naik, sehingga diperlukan metode eksplorasi dan interpretasi yang lebih efektif sehingga produksi bisa ditingkatkan, salah satu nya dengan menggunakan Colored Inversion. Tujuan dari penelitian yang dilakukan pada kasus offshore sebuah lapangan di Kalimantan , Indonesia adalah mengkarakterisasi reservoir daerah tersebut berdasarkan metode Colored Inversion dan metode yang lebih konvensional yaitu Atribut Seismik. Metode Colored Inversion adalah salah satu metode inversi impendansi Akustik seismik 3D yang semua datanya berasal dari data seismik, sehingga mempersingkat waktu pemodelan. Dalam penelitian ini terdapat dua proses analisis reservoir, yang pertama berdasarkan atribut Envelope, Frekuensi, dan Fasa, kedua analisa berdasarkan hasil dari Colored Inversion. Kedua analisa ini kemudian di korelasikan sebagai pembuktian keakuratan identifikasi reservoir hidrokarbon dari proses Colored Inversion. Berdasarkan Hasil penelitian, Metode Colored Inversion sudah bisa memetakan parameter target yang diduga batuan reservoir serta memiliki korelasi yang cukup baik dengan analisi atribut seismik untuk mengkarakterisasikan reservoir hidrokarbon.

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The consumption and demand for oil and gas in Indonesia is increasing year by year. Unfortunately, oil and gas production in Indonesia has not been able to keep up with the ever-increasing demand, so more effective exploration and interpretation methods are needed so that production can be increased, one of which is by using Colored Inversion. The purpose of the research conducted on the offshore case of a field in Kalimantan, Indonesia is to characterize the reservoir area based on the Colored Inversion method and the more conventional method, namely Seismic Attributes. The Colored Inversion Method is one of the 3D seismic acoustic impedance inversion methods in which all the data comes from seismic data, thus shortening the modeling time. In this study, there are two reservoir analysis processes, the first is based on the Envelope, Frequency, and Phase attributes, the second analysis is based on the results of the Colored inversion. These two analyzes are then correlated to prove the accuracy of the identification of the hydrocarbon reservoir from the Colored inversion process. Based on the results of the study, the Colored Inversion Method was able to map the target parameters suspected to be reservoir rocks and had a fairly good correlation with seismic attribute analysis to characterize hydrocarbon reservoirs."

"[ABSTRAKLapangan XXX merupakan lapangan minyak di cekungan Natuna Baratdengan reservoir utama berupa reservoir batu pasir. Ketebalan reservoir padalapangan ini sangat bervariasi sehingga hasil inversi hanya dapat memetakanketebalan reservoir yang mendekati ketebalan tuning.Berdasarkan uji sensitifitas, parameter AI di setiap sumur tidak dapatmembedakan hidrokarbon, sehingga parameter akustik saja tidak dapat diaplikasikandalam karakterisasi reservoir lapangan ini. Namun ketika parameter densitas terpisahdengan parameter kecepatan P, sebaran hidrokarbon dapat dibedakan dengan baik.Kecepatan S tidak tersedia di semua sumur padahal data ini sangat diperlukanuntuk melakukan pengolahan data dengan metode inversi simultan. Oleh karena ituakan dilakukan beberapa estimasi untuk mendapatkan data kecepatan S antara laindengan metode castagna, metode gassmann, metode parsial, metode Xu-White danmetode Lee. Data kecepatan S yang dipakai adalah kecepatan S terbaik yangdiperoleh dari metode Xu White dikarenakan hasil log poisson’s rationya palingmendekati tren kurva saturasi air. Selain itu aspek rasio batuan yangmempertimbangkan nilai porositas dan volume clay, serta kontrol kualitas Vp modeldari metode Xu-White memiliki rasio error minimum jika dibandingkan dengan nilaiVp dari data log.Metode inversi simultan dengan data pre-stack atau partial stackmemungkinkan dilakukannya prediksi parameter Impedansi P, Impedansi S, dandensitas dari data seismik. Selain itu meode inversi simultan dapat dipergunakanmulti wavelet dalam pengolahan datanya. Hasil penampang inversi yang diperolehmenunjukkan bahwa inverse densitas dapat menjelaskan letak sebaran batuanreservoir dan fluida berdasarkan cut off sensitifitas yakni nilai dibawah 2,26 gr/cc.

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ABSTRACTfield is an oil field in West Natuna Basin with sandstone reservoir asprimary target. There was varying reservoir thickness, so the inversion method thatcould only be applied to map reservoir thickness, which close to tuning thickness.Based on sensitivity analysis, Acoustic Impedance parameters couldn’tindicate hydrocarbon appearance for each well, so Acoustic Impedance cannot beapplied for reservoir characterization in this field. Density versus AcousticImpedance could map hydrocarbon appearance.Shear velocity weren’t available where those data was needed for runningsimultaneous inversion method. Predicting velocity shear would be carried out byusing several method such as Castagna, Gassmann, Parsial, Xu-White, and Lee. Thebest estimated velocity shear would be used for inversion, The best estimated shearvelocity from Xu-White method because Xu-White’s poisson ratio log presentssimilar trend with water saturation log (Sw). Moreover, Xu-White’s ratio aspect isalso considering porosity and clay volume value. Based on quality control result, Vpmodel of Xu-White had minimum error ratio compared to Vp from log.Simultaneous inversion with pre-stack and parsial stack data what can be usedfor predicting P-Impedance, S-Impedance, and density from seismic data. Otherwise,this method is also used not only for single wavelet but also multi wavelet. Theinversion result from this study can mapping out the hydrocarbon appearance forreservoir target based on cut off value from sensitivity test of less than 2,26 gr/cc.;X field is an oil field in West Natuna Basin with sandstone reservoir asprimary target. There was varying reservoir thickness, so the inversion method thatcould only be applied to map reservoir thickness, which close to tuning thickness.Based on sensitivity analysis, Acoustic Impedance parameters couldn’tindicate hydrocarbon appearance for each well, so Acoustic Impedance cannot beapplied for reservoir characterization in this field. Density versus AcousticImpedance could map hydrocarbon appearance.Shear velocity weren’t available where those data was needed for runningsimultaneous inversion method. Predicting velocity shear would be carried out byusing several method such as Castagna, Gassmann, Parsial, Xu-White, and Lee. Thebest estimated velocity shear would be used for inversion, The best estimated shearvelocity from Xu-White method because Xu-White’s poisson ratio log presentssimilar trend with water saturation log (Sw). Moreover, Xu-White’s ratio aspect isalso considering porosity and clay volume value. Based on quality control result, Vpmodel of Xu-White had minimum error ratio compared to Vp from log.Simultaneous inversion with pre-stack and parsial stack data what can be usedfor predicting P-Impedance, S-Impedance, and density from seismic data. Otherwise,this method is also used not only for single wavelet but also multi wavelet. Theinversion result from this study can mapping out the hydrocarbon appearance forreservoir target based on cut off value from sensitivity test of less than 2,26 gr/cc., X field is an oil field in West Natuna Basin with sandstone reservoir asprimary target. There was varying reservoir thickness, so the inversion method thatcould only be applied to map reservoir thickness, which close to tuning thickness.Based on sensitivity analysis, Acoustic Impedance parameters couldn’tindicate hydrocarbon appearance for each well, so Acoustic Impedance cannot beapplied for reservoir characterization in this field. Density versus AcousticImpedance could map hydrocarbon appearance.Shear velocity weren’t available where those data was needed for runningsimultaneous inversion method. Predicting velocity shear would be carried out byusing several method such as Castagna, Gassmann, Parsial, Xu-White, and Lee. Thebest estimated velocity shear would be used for inversion, The best estimated shearvelocity from Xu-White method because Xu-White’s poisson ratio log presentssimilar trend with water saturation log (Sw). Moreover, Xu-White’s ratio aspect isalso considering porosity and clay volume value. Based on quality control result, Vpmodel of Xu-White had minimum error ratio compared to Vp from log.Simultaneous inversion with pre-stack and parsial stack data what can be usedfor predicting P-Impedance, S-Impedance, and density from seismic data. Otherwise,this method is also used not only for single wavelet but also multi wavelet. Theinversion result from this study can mapping out the hydrocarbon appearance forreservoir target based on cut off value from sensitivity test of less than 2,26 gr/cc.]"

"[ABSTRAKLapangan XXX merupakan lapangan minyak di cekungan Natuna Baratdengan reservoir utama berupa reservoir batu pasir. Ketebalan reservoir padalapangan ini sangat bervariasi sehingga hasil inversi hanya dapat memetakanketebalan reservoir yang mendekati ketebalan tuning.Berdasarkan uji sensitifitas, parameter AI di setiap sumur tidak dapatmembedakan hidrokarbon, sehingga parameter akustik saja tidak dapat diaplikasikandalam karakterisasi reservoir lapangan ini. Namun ketika parameter densitas terpisahdengan parameter kecepatan P, sebaran hidrokarbon dapat dibedakan dengan baik.Kecepatan S tidak tersedia di semua sumur padahal data ini sangat diperlukanuntuk melakukan pengolahan data dengan metode inversi simultan. Oleh karena ituakan dilakukan beberapa estimasi untuk mendapatkan data kecepatan S antara laindengan metode castagna, metode gassmann, metode parsial, metode Xu-White danmetode Lee. Data kecepatan S yang dipakai adalah kecepatan S terbaik yangdiperoleh dari metode Xu White dikarenakan hasil log poisson?s rationya palingmendekati tren kurva saturasi air. Selain itu aspek rasio batuan yangmempertimbangkan nilai porositas dan volume clay, serta kontrol kualitas Vp modeldari metode Xu-White memiliki rasio error minimum jika dibandingkan dengan nilaiVp dari data log.Metode inversi simultan dengan data pre-stack atau partial stackmemungkinkan dilakukannya prediksi parameter Impedansi P, Impedansi S, dandensitas dari data seismik. Selain itu meode inversi simultan dapat dipergunakanmulti wavelet dalam pengolahan datanya. Hasil penampang inversi yang diperolehmenunjukkan bahwa inverse densitas dapat menjelaskan letak sebaran batuanreservoir dan fluida berdasarkan cut off sensitifitas yakni nilai dibawah 2,26 gr/cc.

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ABSTRACTX field is an oil field in West Natuna Basin with sandstone reservoir asprimary target. There was varying reservoir thickness, so the inversion method thatcould only be applied to map reservoir thickness, which close to tuning thickness.Based on sensitivity analysis, Acoustic Impedance parameters couldn?tindicate hydrocarbon appearance for each well, so Acoustic Impedance cannot beapplied for reservoir characterization in this field. Density versus AcousticImpedance could map hydrocarbon appearance.Shear velocity weren?t available where those data was needed for runningsimultaneous inversion method. Predicting velocity shear would be carried out byusing several method such as Castagna, Gassmann, Parsial, Xu-White, and Lee. Thebest estimated velocity shear would be used for inversion, The best estimated shearvelocity from Xu-White method because Xu-White?s poisson ratio log presentssimilar trend with water saturation log (Sw). Moreover, Xu-White?s ratio aspect isalso considering porosity and clay volume value. Based on quality control result, Vpmodel of Xu-White had minimum error ratio compared to Vp from log.Simultaneous inversion with pre-stack and parsial stack data what can be usedfor predicting P-Impedance, S-Impedance, and density from seismic data. Otherwise,this method is also used not only for single wavelet but also multi wavelet. Theinversion result from this study can mapping out the hydrocarbon appearance forreservoir target based on cut off value from sensitivity test of less than 2,26 gr/cc.;X field is an oil field in West Natuna Basin with sandstone reservoir asprimary target. There was varying reservoir thickness, so the inversion method thatcould only be applied to map reservoir thickness, which close to tuning thickness.Based on sensitivity analysis, Acoustic Impedance parameters couldn?tindicate hydrocarbon appearance for each well, so Acoustic Impedance cannot beapplied for reservoir characterization in this field. Density versus AcousticImpedance could map hydrocarbon appearance.Shear velocity weren?t available where those data was needed for runningsimultaneous inversion method. Predicting velocity shear would be carried out byusing several method such as Castagna, Gassmann, Parsial, Xu-White, and Lee. Thebest estimated velocity shear would be used for inversion, The best estimated shearvelocity from Xu-White method because Xu-White?s poisson ratio log presentssimilar trend with water saturation log (Sw). Moreover, Xu-White?s ratio aspect isalso considering porosity and clay volume value. Based on quality control result, Vpmodel of Xu-White had minimum error ratio compared to Vp from log.Simultaneous inversion with pre-stack and parsial stack data what can be usedfor predicting P-Impedance, S-Impedance, and density from seismic data. Otherwise,this method is also used not only for single wavelet but also multi wavelet. Theinversion result from this study can mapping out the hydrocarbon appearance forreservoir target based on cut off value from sensitivity test of less than 2,26 gr/cc., X field is an oil field in West Natuna Basin with sandstone reservoir asprimary target. There was varying reservoir thickness, so the inversion method thatcould only be applied to map reservoir thickness, which close to tuning thickness.Based on sensitivity analysis, Acoustic Impedance parameters couldn’tindicate hydrocarbon appearance for each well, so Acoustic Impedance cannot beapplied for reservoir characterization in this field. Density versus AcousticImpedance could map hydrocarbon appearance.Shear velocity weren’t available where those data was needed for runningsimultaneous inversion method. Predicting velocity shear would be carried out byusing several method such as Castagna, Gassmann, Parsial, Xu-White, and Lee. Thebest estimated velocity shear would be used for inversion, The best estimated shearvelocity from Xu-White method because Xu-White’s poisson ratio log presentssimilar trend with water saturation log (Sw). Moreover, Xu-White’s ratio aspect isalso considering porosity and clay volume value. Based on quality control result, Vpmodel of Xu-White had minimum error ratio compared to Vp from log.Simultaneous inversion with pre-stack and parsial stack data what can be usedfor predicting P-Impedance, S-Impedance, and density from seismic data. Otherwise,this method is also used not only for single wavelet but also multi wavelet. Theinversion result from this study can mapping out the hydrocarbon appearance forreservoir target based on cut off value from sensitivity test of less than 2,26 gr/cc.]"

"ABSTRACTThe study establishes the thickness and distribution of the ?X? sandstonereservoir in the ASA Field that is located at the southern margin of West NatunaBasin, southwestern South China Sea. The field is located on top of the ?D?horst, which is bordered by the east-northeast (ENE) -west-southwest (WSW)trending basement ridge on the south. By application of discrete Fouriertransform (DFT) on high-resolution 3D seismic data over a short windowcovering the geologic zone of interest, the amplitude spectra of an ?X?sandstone prone channel can help delineate temporal bed thickness variabilityand sandstone distribution.Spectral decomposition is just valid for analysis covered one waveletseismic that will decrease the noise, so that all of frequency range until Nyquistfrequency can be used for analysis. Noise appearance can be used todetermine geological boundaries such as channels and sand bars, but it cannotbe used for the thickness estimation. The maximum value of the first peakfrequency will determine the thinnest layer observable within analysis window.The average tuning thickness ranges is from 30 to 40 feet. The thinnestdetectable layer is about 12 feet that are found at the finite area, this is equalwith 1/12λ, where λ is seismic wavelet wavelength. The tuning thickness of thesandstone reservoir detected by spectral decomposition analysis is thinner thanconventional tuning calculation which is about 35 feet on ¼λ.The paleo-stream flow is interpreted to be from northwest to southeastacross the study area based on spectral decomposition analysis. Faulting wasnot active during ?X? sandstone deposition as evidenced by lack of downthrownthickening and continuity of interpreted sand bars across faulted area.Based on this study, more advance study is recommended to be done tounderstand the optimum window length for spectral decomposition analysisespecially using more than one seismic wavelet to determine sand distributionand its thickness. More advanced method of spectral decomposition analysis isnecessary to detect, within one seismic wavelet, variation in bulk rock propertiesfrom which inferences regarding depositional environment and lithology can bemade."

"Penelitian mengenai identifikasi reservoar karbonat telah dilaksanakan pada lapangan Uli, Formasi Baturaja, Cekungan Jawa Barat Utara. Formasi Baturaja tersusun atas litologi batu karbonat sisipan batulempung dan lapangan Uli merupakan karbonat tight namun terbukti menghasilkan hidrokarbon. Data yang digunakan pada penelitian ini terdiri dari data seismik 2D multi vintage dan data sumur. Penggunaan data seismik multivintage menyebabkan perbedaan fasa, amplitudo dan waktu, oleh sebab itu sebelum masuk ke tahap inversi perlu dilakukan tahap pre-conditioning data, untuk menyeimbangkan perbedaan tersebut. Pada studi ini, inversi seismik yang digunakan adalah CSSI Constrained Sparse Spike Inversion . CSSI merupakan salah satu jenis inversi post-stack yang menggabungkan inversi model based dan inversi sparse spike. Sifat batuan karbonat yang menjadi fokus pada penelitian ini adalah tingkat keheterogenitas yang terlihat dari porositasnya. Porositas karbonat tidak tergantung pada diagenesis batuan tersebut, oleh sebab itu porositas batuan karbonat termasuk porositas sekunder. Namun ada beberapa faktor yang mempengaruhi terbentuknya porositas sekunder tersebut. Hasil cross plot menunjukkan nilai impedansi akustik yang tinggi, densitas yang tinggi, porositas yang rendah, dan nilai Vp yang sangat tinggi. Tujuan dari penelitian ini adalah untuk mengetahui karakter reservoar karbonat, dalam hal ini porositas batuan karbonat yang mempengaruhi zona target yang berupa reservoar tight dapat menghasilkan hidrokarbon. Litologi karbonat dengan densitas tinggi, dapat menjadi reservoar yang baik, hal ini disebabkan oleh tipe porositas zona target yaitu porositas fracture yang dapat meningkatkan permeabilitas sehingga dapat menjadi jalur migrasi bagi hidrokarbon.

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Carbonate reservoirs identification research has been done on Uli field, Baturaja formation, North West Java Basin. Baturaja formation consists of limestones with occasional lempung claystones interbeds and Uli field is tight carbonate but was proven to produce hydrocarbon. The data was used in this study consists of seismic data 2D multi vintage and a well data. Multi vintage data causes difference of phase, amplitude and time, because of that, before inversion, we must do pre conditioning data to balancing the differences.

In this research, inversion seismic method is CSSI Constrained Sparse Spike Inversion . CSSI inversion is the one type of model based inversion to make an initial model and applied sparse spike inversion to get acoustic impedance value. Carbonate rock properties was focused in this research is the level of its heterogeneity. The heterogeneity is seen by their porosity. Carbonate porosity not depend from the diagenesis therefore the carbonate porosity is the secondary porosity. But, there are several factors that influence the secondary porosity of carbonate.

The cross plot result showed high P Impedance, high density, low porosity and very high Vp values. The aim of this research is to know the character of carbonate reservoir, in this case porosity of carbonate which influence that target zone in form tight reservoir can produce hydrocarbon. Carbonate tight in this research can be a good reservoar caused by porosity type is fracture porosity, that can be increase permeability, so the fracture can be a way for hydrocarbon migration."