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"Penelitian dilakukan pada reservoir batupasir di Lapangan "Deju" Formasi Talang Akar, Sub Cekungan Ciputat, Jawa Barat Utara. Struktur geologi yang berkembang di daerah penelitian adalah setengah graben dengan fasies pengendapan yang berkembang dari endapan fluvio-delta hingga endapan laut dangkal di puncak formasi Talang Akar. Karakterisasi waduk di lapangan sangat penting terutama dalam menentukan zona prospek waduk yang akan dikembangkan. Oleh karena itu, identifikasi sebaran litologi batuan reservoir dilakukan dengan menggunakan metode inversi seismik post stack dan sifat fisik reservoir menggunakan analisis petrofisika dapat memudahkan interpreter dalam mengkarakterisasi suatu reservoir. Metodologi penelitian meliputi pengolahan data seismik dan wireline logging, interpretasi horizon dan sesar, pembuatan peta struktur waktu, inversi seismik, dan analisis parameter petrofisika. Dengan metode inversi impedansi akustik seismik didapatkan bahwa trend sebaran reservoir batupasir hanya terkonsentrasi disekitar cekungan dengan range nilai impedansi akustik berkisar antara (8600 - 11000) (m / s) * (g / cc). Dalam perhitungan petrofisika diketahui bahwa sumur LL1 dan LL3 memiliki prospek hidrokarbon yang relatif baik, sedangkan sumur LL4 merupakan sumur prospek non hidrokarbon (dry hole).

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The research was conducted at a sandstone reservoir in the "Deju" Field of the Talang Akar Formation, Ciputat Sub Basin, North West Java. The geological structure that develops in the study area is a half graben with depositional facies that develops from fluvio-deltaic deposits to shallow marine deposits at the top of the Talang Akar formation. Reservoir characterization in the field is very important, especially in determining the zone of the reservoir prospect to be developed. Therefore, identification of reservoir rock lithology distribution is carried out using post stack seismic inversion method and reservoir physical properties using petrophysical analysis can facilitate interpreters in characterizing a reservoir. The research methodology includes seismic data processing and wireline logging, interpretation of horizons and faults, creation of time structure maps, seismic inversion, and analysis of petrophysical parameters. With the seismic acoustic impedance inversion method, it is found that the distribution trend of the sandstone reservoir is only concentrated around the basin with a range of acoustic impedance values ​​ranging from (8600 - 11000) (m / s) * (g / cc). In petrophysical calculations, it is known that LL1 and LL3 wells have relatively good hydrocarbon prospects, while LL4 wells are non-hydrocarbon prospects (dry hole)."

"Penelitian dilakukan pada lapangan 'Sandara' yang terletak kurang lebih 22 km di sebelah timur laut kota Cepu pada Cekungan Jawa Timur Utara. Tujuan penelitian ini adalah untuk mengidentifikasi perbedaan batupasir formasi Ngrayong pada horison L1 dan L5 serta mengetahui karakteristik reservoar batupasir tersebut dengan memanfaatkan data seismik 3D yang dianalisis dengan metode inversi seismik impedansi akustik berbasis model dan data log sumur SAN-01, SAN-02, SAN-04, dan SAN-07 yang di analisis petrofisika dengan metode determin. Hasil menjelaskan bahwa batu pasir pada area sekitar sumur SAN-01, SAN-02 dan SAN-04 yang terdapat di sebelah barat laut area penelitian merupakan reservoar dengan kandungan lempung bernilai antara 30 - 50%, saturasi air antara 60 - 70%, dengan porositasnya bernilai 15 - 20%, permeabilitasnya bernilai lebih dari 250 mD, dan nilai impedansi akustiknya kurang dari 7000 m/s*gr/cc. Sedangkan area yang berada disekitar sumur SAN-07 mengarah sebelah tenggara area penelitian mendeskripsikan reservoar dengan nilai kandungan lempung bernilai rendah yaitu 30%, namun nilai saturasi air bernilai cukup tinggi mendekati 90%, nilai porositasnya lebih rendah yaitu sebesar 10%, permeabilitasnya juga lebih rendah bernilai dari 163 mD dan nilai impedansi akustiknya lebih dari 8000 m/s*gr/cc. Berdasarkan hasil analisa petrofisika dan inversi impedansi akustik, rekomendasi titik bor selanjutnya dapat disarankan pada daerah yang dangkal (di area puncak antiklin), memiliki nilai impedansi di bawah 7000 m/s*g/cc dan berada di sekitar sumur SAN-01, SAN-02, SAN-04.

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The study has been held in 'Sandara' field which located approximately 22 km in the northeast of Cepu region, Northeast Java Basin. The purpose of this study are to identify differences in the sandstone formations of Ngrayong L1 and L5 horizon and to determine the characteristics of the sandstone reservoir by utilizing 3D seismic data that is analyzed with acoustic impedance seismic inversion method based on model and log data from SAN-01, SAN-02, SAN-03, and SAN-04 wells in petrophysical analysis by determin method. The results is the sandstone around SAN-01, SAN-02, and SAN-04 wells have composition of shale volume is between 30 - 50%, water saturation is between 60 - 70%, the porosity value is between 15 - 20%, the permeability is above 250 mD, and the acoustic impedance is bellow 7000 m/s*gr/cc. Meanwhile, the area around SAN-07 well or the area which is located in the southeast direction of the study area have composition of shale volume is around 30%, water saturation is almost 90%, the porosity value is near 10%, the permeability is at 163 mD, and the acoustic impedance is above 8000 m/s*gr/cc. Based on the petrophysical analysis and the acoustic impedance seismic inversion results, the recommendations of the next drilling point are suggested in the crest of the anticline area and have an impedance value below 7000 m/s*g/cc, and located near the SAN-01, SAN-02, SAN-04 wells."

"Telah dilakukan penelitian di lapangan "SG" pada Formasi Talang Akar Sub-Cekungan Jambi dengan studi inversi Acoustic Impedance (AI) dan Elastic Impedance (EI) untuk mengkarakterisasi reservoar. Struktur geologi yang berkembang disekitar daerah penelitian merupakan tinggian Sungai Gelam yang memiliki arah timurlaut (NE) - baratdaya (SW) dengan fasies fluvial pada Formasi Lower Talang Akar dan shallow marine pada Formasi Upper Talang Akar. Metode AI yang melibatkan kecepatan gelombang P (VP) dan densitas menjadi kurang sensitif untuk kehadiran fluida. Untuk itu dilakukan metode EI dengan melibatkan kecepatan gelombang P (VP), kecepatan gelombang S (VS), dan densitas sehingga lebih sensitif terhadap kehadiran fluida. Metode AI di lakukan pada data seismik post stack yang diinversi menghasilkan Volume AI untuk mengetahui lithology sedangkan metode EI dilakukan pada data seismik pre-stack dalam bentuk gather yang di mulai dengan super gather, kemudian merubah domain offset menjadi sudut (angle gather) dan menghasilkan data seismik near angle stack dan far angle stack yang selanjutnya diinversi menghasilkan volume EI near dan far untuk mengetahui sebaran fluida gas dengan pemilihan zona gas berdasarkan crossplot hasil inversi EI near dan far. Di dapatkan hasil pada penampang AI, zona sand berada pada nilai 20.500 ft/s*g/cc sampai dengan 29.000 ft/s*g/cc dan hasil crossplot inversi EI near dan far pada zona sand yang berpotensi mengandung gas didapatkan ketika nilai EI far lebih kecil dibandingkan nilai EI near. Sebaran reservoar yang berpotensi mengandung gas berada di sebelah barat daya sampai ke utara daerah penelitian ini.

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Acoustic Impedance (AI) and Elastic Impedance (EI) inversion study had been done on “SG” field on Talang Akar Formation, Sub-Basin Jambi for reservoir characterization. Geological structure that developed in this study area is a Sungai Gelam high which has North East (NE) – South West (SW) direction with fluvial facies in Lower Talang Akar Formation and also shallow marine facies in Upper Talang Akar Formation. AI method which involve P-wave velocity and density is insensitive to fluid. Thus, EI method which involve P-wave velocity, density and S-wave velocity implemented to made more sensitive to fluid presence. AI method had been done on seismic post stack data which inverted to AI volume to understand lithology of the field while EI method had been done on pre-stack seismic data gather which starts with super gather, then transform offset domain to angle domain and generate seismic near angle stack and far angle stack herein after inverted to generate EI volume near and far to perceive gas fluid distribution by gas zone selection based on crossplot inversion result of EI near and far. The result on AI section, sand zone is on 20,500 ft/s*g/cc up to 29,000 ft/s*g/cc and result of crossplot inversion EI near and far on sand zone, which potentially contain gas, obtained when EI far smaller than EI near. Reservoir distribution and potentially contain gas is on South-West to North of this area."

"Metode inversi EEI dapat mengkarakterisasi reservoar batuan, baik litologi maupun kandungan fluida pengisi pori. Metode EEI diharapkan dapat mengkarakterisasi reservoar di lokasi penelitian yang memiliki perselingan batuan pasir dan lempung dengan ketebalan kurang dari 60 ft. Parameter-parameter yang digunakan untuk melakukan inversi EEI pada penelitian ini adalah parameter yang memiliki koefisien korelasi yang tinggi antara log target dan log parameter pada sudut tertentu best chi angle . Parameter yang digunakan untuk melakukan inversi EEI pada penelitian ini adalah impedansi P AI , Vp/Vs, porositas total PHIT , dan volum lempung VCL.Hasil dari penelitian menunjukkan bahwa Formasi Lower Sihapas memiliki batuan pasir yang lebih dominan dibandingkan dengan Formasi Upper Sihapas. Pada batuan pasir di Formasi Lower Sihapas terdapat konten minyak yang ditandai dengan nilai volume lempung rendah, Vp/Vs rendah, dan saturasi air bernilai 25 - 60.

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EEI inversion method can characterize reservoir rock, either lithology and fluid content. EEI method hopefully can characterize reservoir in research area that have lithology of sand and shale which have less than 60 ft thickness. Parameters that are used in EEI inversion are parameters that have high value of correlation coefficient Parameters that are used in this research are P impedance, Vp Vs, total porosity PHIT , and volume of clay VCL.

The results show that lithology in Lower SIhapas Formation have more dominant sandstone than Upper Sihapas Formation. Sandstone in Lower Sihapas Formation have oil content which is identified by low value of VCL, low value of Vp Vs, and water saturation value range from 25 60."

"Daerah penelitian terletak di Sunda Basin yang merupakan bagian dari Cekungan Northwest Java yang terletak di offshore. Cekungan ini terbukti produktif, namun aktivitas eksplorasi saat ini di daerah penelitian ini jarang. Penelitian difokuskan pada reservoir hidrokarbon dari formasi karbonat di Lapangan 'X', yang dikenal sebagai Formasi Batu Raja Atas. Lapangan ini memiliki dua sumur untuk diteliti, yaitu Sumur GD1 dan GD2, keduanya merupakan sumur deviasional dan memiliki jarak yang berdekatan satu sama lain. Dalam menentukan reservoir hidrokarbon di daerah ini, analisis petrofisika dan metode inversi seismik telah dilakukan. Keduanya akan digunakan untuk menganalisis reservoir hidrokarbon sebagai hasil utama. Parameter analisis petrofisika terdiri dari permeabilitas, densitas, volume shale, porositas dan saturasi air. Selain itu, inversi seismik menerapkan metode impedansi akustik untuk menunjukkan kenampakan geologi di bawah permukaan, sehingga dapat mengidentifikasi karakterisasi reservoir. Nilai Impedansi Akustik menunjukkan bahwa zona minat di Batu Raja Atas atau diperpendek formasi UBR memiliki rentang interval dari 17.000 hingga 22.000 (ft/s)*(g/cc), sehingga kedua metode tersebut dapat membuktikan formasi ini memiliki karakterisasi yang baik sebagai target utama atau reservoir. Berdsarkan analisis petrofisika, hasil perhitungan parameter volume shale, saturasi air, dan porositas yang telah dianalisis menunjukkan bahwa area zone of interest memiliki reservoir hidrokarbon yang cukup baik. Hal tersebut dapat dilihat dari nilai rata-rata volumei shalei sebesari kurang dari sama dengan 40%, nilaii saturasii airi sebesari kurang dari sama dengan 0.43 v/v, dan nilaii porositasi sebesari 0.117-0.13 v/v.

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The study area is located in Sunda Basin which is part of Northwest Java Basin that lies on offshore. The basin is proven to be prolific, however, the current exploration activity in this study area is sparse. The study is focused on the hydrocarbon reservoir of the carbonate formation, which is known as Upper Batu Raja Formation. This research has two wells to be researched, which are Well GD1 and GD2, both of them are deviational wells and have close distance with each other. To specifically determine the hydrocarbon reservoir in this area, a petrophysical analysis and seismic inversion method have been carried out. Both of them will be used to analyze the hydrocarbon reservoir as the main result. The parameters of petrophysical analysis consist of permeability, density, shale volume, porosity and water saturation. Aside from that, the seismic inversion applies acoustic impedance method to show the geological appearance in the subsurface, therefore it can identify the reservoir characterization. The Acoustic Impedance value shows that the zone of interest in Upper Batu Raja or as shorten as UBR formation has interval range from 17000 to 22000 (ft/s)*(g/cc), hence, these methods promptly prove this formation has good characterization as the main target or reservoir. According to petrophysical analysis, the results of shale volume, water saturation, and porosity which have been analyzed show that zone of interest has a good hydrocarbon reservoir. It has been proved from the average calculation of shale volume more or less 40%, water saturation more or less 0.43 v/v, and porosity in range 0.117-0.13 v/v."

"Penelitian ini menggunakan inversi simultan untuk karakterisasi reservoir batupasir dengan target upper dan lower Sihapas di Cekungan Sumatera Tengah. Inversi Simultan dilakukan pada data angle gather dari 3D seismik pre-stack time migration dan data sumur sebagai kontrol data. Data seismik terdiri atas 280 inline dan 760 crossline. Agar kualitas data meningkat, data seismik diubah menjadi domain sudut, dilakukan proses conditioning data untuk mereduksi noise dan meningkatkan signal to noise ratio S/N. Dari angle gather kemudian dibagi menjadi tiga domain yang berbeda yaitu near angle 5-15 , mid angle 14-24 , dan far angle 23-34. Analisa pra-inversi dilakukan untuk melihat korelasi antara hasil inversi dengan kontrol data sumur untuk mendapatkan error yang kecil. Hasil inversi simultan adalah impedansi-p, impedansi-s, densitas, dan rasio Vp/Vs untuk melihat sebaran litologi batupasir di zona target. Pada model impedansi-p didapatkan nilai pasir sebesar 23.000-34.000 ft/s g/cc, impedansi-s sebesar 13.000-21.000 ft/s g/cc, rasio Vp/Vs sebesar 1.5-1.8, dan densitas kurang baik dalam menggambarkan sebaran pasir karena tidak mampu memisahkan antara shale dan batupasir. Sebaran batupasir banyak ditemukan di daerah target Lower Sihapas.

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In this research we used simultaneous inversion for characterization sandstones reservoir with target upper and lower Sihapas in Sumatera Tengah basin. Simultaneous inversion is performed by angle gather from 3D seismic data pre stack time migration and one well data as a control. Seismic data has 280 inline and 760 crossline. For improving data quality, seismic data is changed to angle domain, doing the conditioning data process to decrease noise and improves signal to noise ratio S N. From angle gather divided into difference three domain there are near angle 5 15 , mid angle 14 24 , and far angle 23 34. Pre Inversion analysis is done to get the small error. Simultaneous inversion's result are p impedance, s impedance, density, and Vp Vs ratio to see the distribution sandstone lithology in the target zone. In p impedance's model is gotten the value of sandstone is 23000 34000 ft s g cc, s impedance is 13000 21000 ft s g cc, Vp Vs ratio is 1.5 1.8 and density is not good for distributing of sandstone because can not separates between sandstone and shale. A lot of distribution of sandstone is found in targer area Lower Sihapas."

"[ABSTRAKIdentifikasi keberadaan hidrokarbon di bawah permukaan bumi merupakansalah satu tujuan utama dalam eksplorasi lapangan minyak bumi dalam usahamengidentifikasi keberadaan hidrokarbon. Impedansi-poisson yang merupakansalah satu metoda yang digunakan untuk mendiskriminasi sifat fisis batuanterhadap fluida dengan cara mengamati sensitivitas dari rasio poisson telahditerapkan lebih lanjut untuk menghasilkan suatu metoda turunan yang lebih baik.Pendekatan sifat fisika batuan antara impedansi-poisson dengan log sumuran yangmerepresentasikan properti batuan menghasilkan suatu metoda turunan yangdinamakan impedansi-litologi. Sedangkan pendekatan sifat fisis fluida yangterkandung didalam batuan terhadap impedansi-poisson menghasilkan diskriminasikandungan fluida didalam batuan yang kemudian dinamakan impedansi-fluida.Metoda TCCA – Target Coeffisien Corellation Analysis – yang digunakanuntuk mencari koefisien korelasi tertinggi dari sifat fisis batuan terhadapimpedansi-poisson telah digunakan dalam penelitian ini untuk menghasilkan logsumuran impedansi-litologi dan impedansi-fluida yang kemudian di propagasidengan neural network. Hasil propagasi impedansi-litologi digunakan sebagaiinput untuk kalkulasi atribut koherensi yang diperkuat dengan hasil propagasiimpedansi-fluida untuk menghasilkan prediksi sebaran batuan reservoar.Dari hasil penelitian pada horison FS33 terlihat pola channel yangterbentuk dan tervalidasi dengan data sumur. Demikian juga pada sayatan horisonFS37, pola channel batuan reservoar terlihat dengan jelas dan tervalidasi terhadapdua sumur yang dilalui. Sedangkan pada sayatan horison FS42 selainteridentifikasi pola channel reservoar yang terbentuk, teridentifikasi juga batuankarbonat yang divalidasi dengan data sumur dan data batuan inti

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ABSTRACTHydrocarbon identification in subsurface is one of main goals in petroleumexploration so that the litho-fluid content discriminations are a part of hydrocarbonidentifications which have been widely applied today. Poisson-impedance which isone of the new methods that are used to discriminate rocks by examining thesensitivity of physical rock properties of poisson-ratio has been further developedto produce derivatives method. Physical properties approaches between poissonratioand a well-log which represents rock properties can be used to get highestcorrelation to produce a new derivative well-log named lithology-impedance. As afluid-rock properties approach between poisson-ratio and a well-log representslitho-fluid content properties produces a new derivative well-log named fluidimpedance.TCCA method –Target Coeffisien Corellation Analyst– is used to find thehighest correlation coefficient of the physical properties of rock fluid on thepoisson ratio has been used in this study to generate two new derivatives well-logwhich would be propagated by means of neural-networks. The result of lithologyimpedancepropagation is further proceed with seismic coherence attribute as areflection of geology and stratigraphy forms which are then combined with fluidimpedancepropagation result to emphasize reservoir prediction distributionlaterally.The study results of FS33 slicing discovers sand channels pattern andvalidated by well-log. Similarly with horizon slicing of FS37, patterns of sandchannels reservoir are clearly visible and validated against two well-logs thatpassed. While on horizon slicing of FS42 besides discovering sand channels,carbonate rocks is also identified which is validated by well-log and core sampleanalyst.;Hydrocarbon identification in subsurface is one of main goals in petroleumexploration so that the litho-fluid content discriminations are a part of hydrocarbonidentifications which have been widely applied today. Poisson-impedance which isone of the new methods that are used to discriminate rocks by examining thesensitivity of physical rock properties of poisson-ratio has been further developedto produce derivatives method. Physical properties approaches between poissonratioand a well-log which represents rock properties can be used to get highestcorrelation to produce a new derivative well-log named lithology-impedance. As afluid-rock properties approach between poisson-ratio and a well-log representslitho-fluid content properties produces a new derivative well-log named fluidimpedance.TCCA method –Target Coeffisien Corellation Analyst– is used to find thehighest correlation coefficient of the physical properties of rock fluid on thepoisson ratio has been used in this study to generate two new derivatives well-logwhich would be propagated by means of neural-networks. The result of lithologyimpedancepropagation is further proceed with seismic coherence attribute as areflection of geology and stratigraphy forms which are then combined with fluidimpedancepropagation result to emphasize reservoir prediction distributionlaterally.The study results of FS33 slicing discovers sand channels pattern andvalidated by well-log. Similarly with horizon slicing of FS37, patterns of sandchannels reservoir are clearly visible and validated against two well-logs thatpassed. While on horizon slicing of FS42 besides discovering sand channels,carbonate rocks is also identified which is validated by well-log and core sampleanalyst.;Hydrocarbon identification in subsurface is one of main goals in petroleumexploration so that the litho-fluid content discriminations are a part of hydrocarbonidentifications which have been widely applied today. Poisson-impedance which isone of the new methods that are used to discriminate rocks by examining thesensitivity of physical rock properties of poisson-ratio has been further developedto produce derivatives method. Physical properties approaches between poissonratioand a well-log which represents rock properties can be used to get highestcorrelation to produce a new derivative well-log named lithology-impedance. As afluid-rock properties approach between poisson-ratio and a well-log representslitho-fluid content properties produces a new derivative well-log named fluidimpedance.TCCA method –Target Coeffisien Corellation Analyst– is used to find thehighest correlation coefficient of the physical properties of rock fluid on thepoisson ratio has been used in this study to generate two new derivatives well-logwhich would be propagated by means of neural-networks. The result of lithologyimpedancepropagation is further proceed with seismic coherence attribute as areflection of geology and stratigraphy forms which are then combined with fluidimpedancepropagation result to emphasize reservoir prediction distributionlaterally.The study results of FS33 slicing discovers sand channels pattern andvalidated by well-log. Similarly with horizon slicing of FS37, patterns of sandchannels reservoir are clearly visible and validated against two well-logs thatpassed. While on horizon slicing of FS42 besides discovering sand channels,carbonate rocks is also identified which is validated by well-log and core sampleanalyst., Hydrocarbon identification in subsurface is one of main goals in petroleumexploration so that the litho-fluid content discriminations are a part of hydrocarbonidentifications which have been widely applied today. Poisson-impedance which isone of the new methods that are used to discriminate rocks by examining thesensitivity of physical rock properties of poisson-ratio has been further developedto produce derivatives method. Physical properties approaches between poissonratioand a well-log which represents rock properties can be used to get highestcorrelation to produce a new derivative well-log named lithology-impedance. As afluid-rock properties approach between poisson-ratio and a well-log representslitho-fluid content properties produces a new derivative well-log named fluidimpedance.TCCA method –Target Coeffisien Corellation Analyst– is used to find thehighest correlation coefficient of the physical properties of rock fluid on thepoisson ratio has been used in this study to generate two new derivatives well-logwhich would be propagated by means of neural-networks. The result of lithologyimpedancepropagation is further proceed with seismic coherence attribute as areflection of geology and stratigraphy forms which are then combined with fluidimpedancepropagation result to emphasize reservoir prediction distributionlaterally.The study results of FS33 slicing discovers sand channels pattern andvalidated by well-log. Similarly with horizon slicing of FS37, patterns of sandchannels reservoir are clearly visible and validated against two well-logs thatpassed. While on horizon slicing of FS42 besides discovering sand channels,carbonate rocks is also identified which is validated by well-log and core sampleanalyst.]"

"ABSTRAKImpedansi akustik dan seismik inversi seismik multi-atribut adalah sejumlah metode seismik yang dapat digunakan untuk memetakan distribusi reservoar batu pasir. Dengan menggunakan metode ini, kita dapat memisahkan batupasir dan sumur serpih di Formasi Talang Akar yang ditemukan di Lapangan "Essen", Sub-Basin Ciputat. Kedua metode ini akan dibandingkan satu sama lain untuk mendapatkan hasil yang lebih valid dalam pemetaan reservoar batu pasir. Metode seismik inversi impedansi akustik yang digunakan dalam penelitian ini adalah metode berbasis model. Sedangkan metode multi-atribut yang digunakan adalah jaringan saraf dalam memetakan volume sinar gamma, volume serpih, dan porositas. Hasil inversi tidak dapat menggambarkan distribusi batupasir cukup baik karena rentangnya terlalu besar dan ada tumpang tindih pada nilai impedansi akustik batupasir dengan rentang (8000-12000) (m / s) * (g / cc). Hasil multi-atribut gamma ray, volume serpih dan porositas, telah terbukti secara konsisten menunjukkan distribusi batupasir yang memiliki kecenderungan dalam distribusi zona reservoar NW-SE (North West-South East). Dari hasil analisis yang dilakukan ada beberapa area potensial yang berpotensi menjadi area pengembangan selanjutnya, yaitu distribusi batupasir di bagian utara dengan porositas efektif tinggi, dan seal yang baik. Di selatan dengan volume besar batupasir, serta distribusi terbentuk pada saluran yang mengelilingi patahan.

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ABSTRACTAcoustic impedance and seismic multi-attribute seismic inversion are a number of seismic methods that can be used to map the distribution of sandstone reservoirs. Using this method, we can separate sandstones and shale wells in the Talang Akar Formation found in the "Essen" Field, Ciputat Sub-Basin. These two methods will be compared with each other to get more valid results in sandstone reservoir mapping. The acoustic impedance inversion seismic method used in this study is a model based method. Whereas the multi-attribute method used is a neural network in mapping the volume of gamma rays, shale volume, and porosity. The inversion results cannot describe the sandstone distribution well enough because the range is too large and there is an overlap in the acoustic impedance value of the sandstone with a range (8000-12000) (m / s) * (g / cc). The results of the multi-attribute gamma ray, shale volume and porosity, have been shown to consistently show the distribution of sandstones that have a tendency in the distribution of the NW-SE (North West-South East) reservoir zone. From the results of the analysis conducted there are several potential areas that have the potential to become further development areas, namely sandstone distribution in the north with high effective porosity, and good seals. In the south with a large volume of sandstones, and distribution is formed in the channel that surrounds the fault."

"Lapangan ‘R’ merupakan lapangan eksplorasi yang berada pada Cekungan Jawa Timur Bagian Utara. Data yang digunakan pada studi ini meliputi data seismik darat 2D post stack danpre stack serta data log sumur. Pada data post stack terlihat adanya bright spot sebagai indikator keberadaan hidrokarbon (direct hidrokarbon indicator). Anomali DHI yang muncul pada data post stack memperlihatkan adanya energy atau nilai amplitudo yang membesar disbanding amplitudo sekitarnya. Anomali ini menjadi acuan untuk menganalisa anomali amplitudo terhadapoffset yang dikenal dengan anomali AVO. Fokus studi pada formasi Ngrayong dimana berdasarkan geologi regional merupakan reservoar utama dengan bukti outcrop yang memiliki porositas dan permeabilitas sangat baik. Analisa AVO dilakukan untuk menjawab penyebab anomali amplitudo apakah dikarenakan perbedaan litologi atau adanya fluida yang mengisi rongga batuan. Rekonstruksi penjalaran gelombang dilakukan dengan mengamati setiap CDP dari berbagai sudut dan offset yang berbeda-beda. AVO inversi melibatkan parameter gelombang S yang sensitive terhadap keberadaan fluida. Pada inversi AVO parameter fisis batuan lain seperti poisson ratio, Mu-rho (μρ), lambda-rho (λρ) dapat dihitung sebagai pendekatan keberadaan zona fluida. Hasil analisa sumur mengidentifikasi adanya reservoar batupasir terisi gas di formasi Ngrayong pada twt sekitar 717-721 ms untuk R-1, 270 ms - 275 ms pada sumur C-1 dan 968.2 ms - 970 ms pada K-1. Sebaran lateral reservoar berdasarkan hasil analisa integrasi AVO,dapat diamati melalui sebaran geometri reservoar pada lintasan 09TJP-07 yang membentang dari CDP 2507-2486 dan pada 09TJP-17 dari CDP 3606 - 3574. Hasil inversi P-impedance yang rendah pada twt yang sesuai degan hasil analisa sumur. Hasil Analisa dan Inversi AVO reservoar pada 09TJP-17 dan 09TJP-07 dapat terdeliniasi dengan nilai positif pada bagian atas dan bawah reservoar dan nilai LMR yang kontras pada reservoar terisi gas. Hasil AVO menyimpulkan gas yang mengisi reservoar adalah kelas II dan III yakni memiliki kontras impedansi yang kecil dengan sekitanya dan impedansi bernilai rendah.

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This study area located in North Earth Java Basin and it is still explorated. In this study, both seismic data post stack and prestack was provided. There was Direct Hidrocarbon Indicator (DHI) on seismic post stack. This DHI represent there are laterally strong energy or strong amplitude on that spot .DHI anomalies that arise post-stack data showed energy or amplitude value of the enlarged compared to the surrounding amplitude. This anomaly which identifies the anomaly amplitude against an offset known as AVO anomaly. Focus study on Ngrayong formation whereas base on geological regional whereas this formation have good porosity and permeability on outcrop.

AVO analysis used to know the causes of the anomaly amplitude is due to differences in lithological or fluid that fills the pore of rocks. Reconstruction of wave propagation is observed every CDP from different angle and offsets. AVO inversion involving S wave parameters that are sensitive to the presence of fluid. With AVO inversion, rock physical parameters such as Poisson ratio, Mu-rho (μρ), lambda-rho (λρ) can be calculated as the approach of fluidzone.

Results of well analysis identified the presence of reservoir filled with gas in Ngrayong Formations at around 717-721 ms for R-1, 270 ms - 275 ms in the well C-1 and 968.2 ms - 970 ms in K-1. Lateral reservoir distribution is based on the results of the integration analysis of AVO and Inversion methods, the distribution of reservoir geometry inline 09TJP-07 find at CDP 2507 to 2486 and in 09TJP-17 from CDP 3606 - 3574.

The results of inversion P-impedance, low impedance values in accordance with the results of the analysis wells. From AVO methods reservoir on 09TJP-17 and 09TJP-07 can deliniated with positive values at the top and base of the reservoir and contrast LMR on the reservoir gas. Gradient of this target concluded that reservoar fills by gas class II and III which has a low contrast impedance with the surrounding area and have low impedance value."

"Inversi Extended Elastic Impedance (EEI) merupakan teknik inversi seismik yang secara optimal dapat memprediksi karakter dan keberadaan reservoar hidrokarbon dengan perluasan sudat datang gelombang dari -90° hingga 90°. Pada penelitian Lapangan ?Q? Sub-Cekungan Jambi, inversi EEI mampu mengkarakterisasi reservoar batupasir dan memprediksi keberadaan gas maupun minyak melalui parameter Vp/Vs ratio, lambda-rho dan mu-rho. Dalam inversi EEI dilakukan korelasi untuk mencari nilai korelasi maksimum pada sudut chi (χ) tertentu dari setiap parameter dengan melakukan korelasi antara log EEI dengan log target. Nilai sudut chi (χ) optimum atau best-chi agle ini kemudian digunakan untuk membuat volume scaled reflectivity yang dipakai dalam pembuatan model awal dan juga inversi. Proses inversi dilakukan dengan menggunakan inversi post-stack model based yang baik digunakan pada reservoar lapisan tipis. Hasil inversi selanjutnya digunakan untuk mengetahui penyebaran reservoar dimana hasilnya menunjukkan adanya kemungkinan resevoar yang mengandung gas dan minyak. Pada penelitian, nilai Vp/Vs ratio berkisar antara 16-18, nilai mu-rho berkisar antara 25-35 (GPa*(g/cc)) dan lambda-rho untuk gas berkisar antara 20-22 (GPa*(g/cc)) dan lambda-rho untuk minyak berkisar 25-27 (GPa*(g/cc)).

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Extended Elastic Impedance (EEI) inversion method is a seismic inversion technique that optimally can predict the character and the presence of hydrocarbon reservoir with the expansion of the angle?s coming wave from -90 ° to 90 °. In the field of research 'Q' Sub-Basin Jambi, EEI is able to characterize sandstones reservoir and predict the existence of gas or oil through the parameter of Vp / Vs ratio, lambda-rho and mu-rho. EEI is performed in correlation to seek the maximum correlation value at an optimum chi (χ) angle of each parameter specified by the correlation between the targets? logs with the EEI?s logs. Optimum chi (χ) angle or a best-chi angle is then used to create a scaled volume reflectivity that is used in making the initial model and also in inversion process. Inversion is done using post-stack inversion based model which is best used on thin reservoir layer. Inversion results are then used to determine the spread of the reservoir where the results indicate the possibility resevoar containing gas and oil. In the study, the value of Vp / Vs ratio ranged between 16-18, the mu-rho values ​​ranged between 25-35 (GPa * (g / cc)), the lambda-rho values for gas ranged between 20-22 (GPa * (g / cc)) and for oil ranged between 25-27 (GPa * (g / cc)).

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