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"[ABSTRAKFormasi Baong bagian bawah bertanggung jawab sebagai batuan indukyang mengisi reservoar batupasir pada lapangan minyak dan gas di bagiantenggara Cekungan Sumatera Utara. Penelitian ini mengungkapkan data dan faktadari laboratorium, pengeboran, wireline well log dan seismik melalui studi analisapetrofisika, geokimia, geomekanika dan geofisika Formasi Baong bagian bawah.Pemahaman tentang geokimia, mineralogi dan geomekanika serpih sangat pentinguntuk memahami bagaimana reservoir serpih memiliki potensi untuk cadangandan produksi ketika dilakukan stimulasi. Analisis laboratorium geokimiadigunakan untuk menentukan kekayaan, kematangan dan kerogen tipe. Penelitianini mengklasifikasikan serpih berdasarkan kekayaan organik, kematangan, jenis,kekuatan serpih, kerapuhan serpih dan kandungan clay. Formasi Baong bagianbawah yang menjadi target pada studi ini terletak pada kedalaman 1778-2428 m(TVD), memiliki material organik yang kaya dengan TOC berkisar antara 1,88-3,85% wt, tingkat kematangan 12% sudah matang dan 88% belum matang, sertamenghasilkan 20% kerogen tipe III dan 80% kerogen tipe II/III sehingga dapatdijadikan sebagai batuan induk yang berpotensi menghasilkan gas dangas/minyak. Rigiditas Formasi Baong bagian bawah sangat sangat brittle denganmemiliki rata ? rata kandungan mineral kuarsa 33,7% dan mineral brittle sepertikalsit 8,8%, dolomit 1,8% dan siderit 0,9%, serta brittle 80% dan less brittle 20%,sehingga dapat dilakukan hyhraulic fracturing dengan baik. Nilai impedansiserpih Formasi Baong bagian bawah berkisar antara 20203 ? 24615 ((ft/s)*(g/cc)).

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ABSTRACTThe Lower Baong Formation is responsible for source rock filled upsandstones reservoir in the oil and gas field in the southeastern part of NorthSumatra Basin. This study reveals the data and facts from the laboratory, drilling,wireline well logs and seismic through the analysis study of petrophysics,geochemistry, geomechanics and geophysics of Lower Baong Formation. Anunderstanding of shale geochemistry, mineralogy and geomechanics is veryimportant to understand how the shale reservoir has the potential to reserve andproduce when carried out stimulation. Geochemical laboratory analysis is used todetermine the richness, maturity and kerogen type. This study classify shale basedon organic richness, maturity, type, shale strengthness, shale brittleness and claycontent. The Lower Baong Formation being targeted in this study lies at a depthof 1778-2428 m (TVD), has a rich organic material with TOC ranging from 1.88to 3.85 wt%, the maturity level of 12% is mature and immature 88%, and generate20% kerogen type III and 80% kerogen type II / III so it can be used as a sourcerock potential to produce gas and gas / oil. Lower Baong Formation rigidity arevery brittle by having the averages 33.7% quartz mineral content and brittleminerals such as 8.8% calcite, 1.8% dolomite and siderite 0.9%, and brittle 80%and less brittle 20%, so it can be done hyhraulic fracturing very well. Sahle valuesof Lower Baong Formation bottom ranges from 20203-24615 ((ft/s)*(g / cc))., The Lower Baong Formation is responsible for source rock filled upsandstones reservoir in the oil and gas field in the southeastern part of NorthSumatra Basin. This study reveals the data and facts from the laboratory, drilling,wireline well logs and seismic through the analysis study of petrophysics,geochemistry, geomechanics and geophysics of Lower Baong Formation. Anunderstanding of shale geochemistry, mineralogy and geomechanics is veryimportant to understand how the shale reservoir has the potential to reserve andproduce when carried out stimulation. Geochemical laboratory analysis is used todetermine the richness, maturity and kerogen type. This study classify shale basedon organic richness, maturity, type, shale strengthness, shale brittleness and claycontent. The Lower Baong Formation being targeted in this study lies at a depthof 1778-2428 m (TVD), has a rich organic material with TOC ranging from 1.88to 3.85 wt%, the maturity level of 12% is mature and immature 88%, and generate20% kerogen type III and 80% kerogen type II / III so it can be used as a sourcerock potential to produce gas and gas / oil. Lower Baong Formation rigidity arevery brittle by having the averages 33.7% quartz mineral content and brittleminerals such as 8.8% calcite, 1.8% dolomite and siderite 0.9%, and brittle 80%and less brittle 20%, so it can be done hyhraulic fracturing very well. Sahle valuesof Lower Baong Formation bottom ranges from 20203-24615 ((ft/s)*(g / cc)).]"

"Tujuan dari penelitian ini adalah untuk menentukan potensi shale oil di Formasi Anggota Banuwati Shale, Cekungan Asri, dengan melihat parameter Total Organic Carbon (TOC), Maturity, dan Brittleness Index. TOC dimodelkan dengan melakukan crossplot antara TOC measured dengan log gamma ray, log density, log neutron porosity, dan log P wave (multi linier regresi). Brittleness index dimodelkan dengan mengkombinasikan log Young’s modulus dan log Poisson’s ratio, serta dibandingkan dengan brittleness index yang dimodelkan dari beberapa data x ray diffraction. Maturity dijadikan sebagai salah satu parameter untuk menentukan kategori TOC, oil atau gas. Shale yang memiliki TOC > 1 wt.%, memiliki thickness > 50 ft, dan brittle merupakan zona potensi shale oil. Shale di Formasi Anggota Banuwati Shale didominasi oleh tipe kerogen I, lingkungan pengendapan lacustrine, dengan early mature di kedalaman 8132 ft (Delima-1). Berdasarkan inversi simultan, diketahui bahwa persebaran shale yang berpotensi menjadi shale oil berada di arah Timur Laut dari sumur Delima-1, pada depth > 9500 ft, dengan ketebalan 200 – 300 ft.

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The purpose of this research is to determine the potency of shale oil in Member Banuwati Shale Formations, Asri Basin, with use Total Organic Carbon (TOC), Maturity, and Brittleness Index parameter. TOC is modeled by multiple linear regresion method. This method is crossplot between TOC measured with gamma ray log, density log, neutron porosity log, and P wave log. Brittleness index is modeled by combining Young's modulus log and Poisson's ratio log, where this model called brittlenes index geomechanic model. After that this model compared with brittleness index model from mineralogy. Maturity is one of the parameters used to determine category of TOC, oil or gas. Shale which has TOC more than 1 wt.%, has a thickness more than 50 ft, and has brittle is potential to be shale oil. Shale in Member Banuwati Shale Formation is dominated by kerogen type I, lacustrine depositional environment, with early mature in depth 8132 ft (Delima-1). Based on simultaneous inversion, known that distribution of shale which is potentially into lying in the northeast of Delima-1 well, in depth > 9500 ft, with thickness 200 – 300 ft."

"Penelitian yang dilakukan di lapangan Abiyoso pada formasi gumai bertujuan untuk memperkirakan daerah yang berpotensi sebagai shale reservoir berdasarkan parameter impendansi akustik dan analisa log. Log gamma ray, neutron (NPHI) dan density (RHOB) secara efektif dapat mengidentifikasi kandungan material organik pada batu serpih. Terdapat hubungan antara Vp pada porositas rendah terhadap kematangan kerogen. Vp meningkat dengan meningkatnya tingkat kematangan kerogen. Hasil inversi menunjukkan bahwa pada daerah Top Horizon 3, 4 dan 5 kerogen telah matang, dengan nilai AI (21000 - 25000) (ft/s)*(g/cc).

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Research conducted in the filed Abiyoso at gumai formation aims to estimate the potential area as a shale reservoir based on parameters acoustic impedance and log analysis. Gamma ray log, neutron (NPHI) and density (RHOB) is efective to organic matter identification of shale. The maturity of kerogen can be related to Vp at low-porosity.Vp increas with increasing maturity. Inversion result show that kerogen is mature on the area of Top Horizon 3, 4 and 5 with AI value (21000 - 25000) (ft/s)*(g/cc)."

"Simultaneous inversion is one of the seismic method which can be used to characterize reservoirs that may also serve as a rock source. In this research, the characterization of shale reservoir is done on the field TAF, in North Sumatra basin with Lower Baong formation as the target formation. A P impedance parameter on the simultaneous inversion method is used to identify the existence of fluids while S Impedance parameter is used to identify the lithology of the target zone. The analysis of the simultaneous inversion is done using partial angle stack method, that which consists of the near angle stack 1 19, the mid angle stack 19 36 and the far angle stack 36 53. The result of the analysis of the gas chromatography of the well data states that there are 2 layers of lithologies on the Baong Formation that which have the indications of hydrocarbon with each layer having the thickness of less than 5 meters. The result of the simultaneous inversion is obtained, with the value of P impedance ranging from 4000 8000 m s gr cc, the value of S impedance ranging from 1500 3000 m s gr cc and the value of density ranging from 2.2 2.5 g cc. These three values are assumed to correlate with the layer that is dominated by shale. The value of P impedance ranging from 8000 12000 m s gr cc, the value of S impedance ranging from 3000 5700 m s gr cc and the density value ranging from 2.5 2.75 g cc are also obtained that which are situated on the bottom of the Lower Baong formation near the top Belumai and are assumed to correlate with the other lithology that which is dominated by sandstone and carbonate. However, the result of the inversion of P Impedance and the Lambda Rho transformation, as well as the crossplot analysis of AI vs SI and the crossplot of LMR, has no indication of hydrocarbon fluids."

"Aplikasi Inversi Seismik Post-Stack dan AVO dalam penyebaran Lapisan Hidrokarbon Gas Pada Lapangan Nauli Formasi Talang Akar Cekungan Sumatera Selatan Lapangan Nauli adalah salah satu lapangan marginal yang berada di wilayah Barat Indonesia dan telah terbukti menghasilkan hidrokarbon minyak dan gas. Lapangan ini berada pada Cekungan Sumatera Selatan dengan target reservoir batupasir pada Formasi Talang Akar. Tujuan dari penelitian ini adalah mengindentifikasi fluida hidrokarbon gas dari data log sumur dan mengintegrasikan dengan data seismik untuk mengetahui kemungkinan penyebarannya di seluruh lapangan. Karakteristik reservoir seperti porositas dan saturasi air dihitung pada masing-masing lapisan di tiap sumur. Metode seismik inversi dipilih untuk memperkirakan attribut P-impedance Zp , S-impedance Zs dan densitas r . Inversi Amplitude Versus Offset diterapkan dengan menggunakan attribut Lambda-Mu-Rho. Perubahan pada hasil inversi Lambda-Mu-Rho dapat memberikan informasi mengenai litologi dan kandungan fluida di dalam pori-pori reservoir. Hasil analisis dan pengolahan mendapatkan nilai porositas efektif pada Lapangan Nauli berkisar antara 10-20 p.u dengan saturasi air 20-70 dengan ketebalan Net pay berkisar antara 2-8 meter. Inversi post-stack menunjukkan adanya anomali impedansi pada skala waktu 1580 ndash; 1590 ms dengan nilai impedansi 22.000 ndash; 25.000 m/s g/cc. Hasil analisis petrofisika menunjukkan posisi ini pada lapisan-X yang merupakan salah satu lapisan pembawa gas gas bearing layer . Attribut inversi AVO Lambda-Mu-Rho LMR mengkonfirmasi adanya kehadiran gas pada anomali impedansi tersebut yang ditandai dengan nilai Lambda-Rho sebesar 11-20 Gpa g/cc relatif bernilai lebih kecil dari nilai Mu-Rho yaitu sebesar 28-32 Gpa g/cc.

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Title Application of Seismic Post Stack Inversion and AVO for Gas Reservoir Delineation in Nauli Field, Talang Akar Formation South Sumatera Basin. Nauli Fields is one of the marginal fields located in the western region of Indonesia and has been proven to produce oil and gas hydrocarbons. This field is located in the South Sumatra Basin with target reservoir is sandstone from Talang Akar Formation.

The purpose of this study is to integrate petrophysical interpretation and seismic data analysis.Reservoir characterization such as porosity and water saturation calculated for each layer within the wells.

Seismic inversion methods chosen to estimate the attributes of P impedance Zp , S impedance Zs dan densitas r . AVO inversion applied using Lambda Mu Rho attribute can provide information on lithology dan fluids content in the reservoirs.

Data processing and analysis shows that the effective porosity for Nauli Field is 10 20 porosity unit p.u with 20 70 water saturation. The thickness of net pay is 2 8 meters. Post stack inversion shows impedance anomaly around 1580 1590 ms with value 22.000 25.000 m s g cc.

Petrophysics analysis estimate this anomaly in layer x with gas fluid estimated. Lambda Mu Rho attribute confirm this fluid with lower Lambda Rho values around 11 20 Gpa g cc than Lambda Rho values around 28 32 Gpa g cc."

"Lapangan Eka terletak di Cekungan Sumatra Tengah, dengan reservoar berupa batuan sedimen tersier utama yang memproduksi hidrokarbon. Reservoar lapisan tipis ini berada Formasi Bekasap dan dibagi menjadi 3 zona reservoar utama Bekasap A, B, dan C. Karakterisasi reservoir dilakukan untuk mendelineasi distribusi reservoir dalam Formasi Bekasap dengan menggunakan inversi seismik, Inversi Deterministik DI , dan Inversi Geostatistik GI. GI adalah metode simulasi yang menggunakan data seismik, hasil DI, dan data log sumur. GI dapat memisahkan reservoir yang tebal menjadi beberapa lapisan tipis yang ketebalan sebenarnya di bawah ketebalan tuning. Analisis cross plot menunjukkan Impedansi Akustik AI tidak dapat membedakan litologi antara pasir dan serpih dalam Formasi Bekasap. Namun, AI cukup baik dalam memisahkan pasir dan serpih pada Bekasap A dan Bekasap B. Lithologi pasir memiliki nilai impedansi akustik yang berkisar antara 18213 - 25043 gr / cm3 ft / s. Pasir berpori reservoir memiliki parameter cutoff tambahan yang porositasnya total, berkisar antara 0.2649 - 0.4136. Hasil DI mencitrakan hasil blocky pada distribusi batu pasir. Keterbatasan inversi deterministik dalam resolusi vertikal membuatnya sulit untuk membedakan reservoar berlapis tipis dan mengasumsikan lapisan tersebut sebagai satuan tubuh pasir yang tebal. DI juga tidak bisa menyelesaikan masalah non-keunikan. Tujuan dari penelitian ini adalah untuk menggambarkan distribusi reservoir dengan resolusi lebih tinggi. GI diterapkan pada alur kerja inversi. Hasil GI dapat mencitrakan distribusi reservoar berlapis tipis yang DI tidak dapat selesaikan.

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Eka field is located in Central Sumatra Basin, the largest principal Indonesia tertiary sediment basin producing hydrocarbon. Having great potential to produce hydrocarbon, Bekasap Formation were divided into 3 reservoir zones Bekasap A, B, and C. Reservoir characterization was conducted to delineate the distribution of reservoir within Bekasap Formation by generating seismic inversions, Deterministic Inversion DI, and Geostatistic Inversion GI . GI is a simulation method honoring seismic data, DI result, and well log data. The GI can separate the blocky layers of the reservoir into several thin layers which thicknesses are below the tuning thickness.

Cross plot analysis showed the Acoustic Impedance AI cannot distinguish lithology between sand and shale in Bekasap Formation. However, AI is was quite good in separating sand and shale on Bekasap A and Bekasap B. The sand lithology has the value of acoustic impedance ranges from 18213 ndash 25043 gr cm3 ft s. The porous sand reservoir has additional parameter cut off which is porosity total, ranging from 0.2649 ndash 0.4136.

DI result shows the blocky event on sand distribution. The limitation of deterministic inversion in vertical resolution makes it hard to differentiate the thin bed layers of reservoir which assumes the layers as one thick body sand. DI cannot resolve the non uniqueness matter. The aim of this research is to delineate the distribution of the reservoir with higher resolution. GI is applied to the inversion workflow. GI results in high definition imaging that can highlight the distribution of the thin bed reservoirs which DI cannot."

"[Saat ini, jumlah kandungan minyak dan gas konvensional yang tersedia semakin terbatas sedangkan cadangan semakin rendah. Oleh karena itu diperlukan eksplorasi akan sumber daya baru, salah satu solusinya adalah dengan memperluas eksplorasi hidrokarbon dengan cara konvensional maupun unconvensional, dan untuk mengurangi tingginya kegagalan dalam tahapan eksplorasi ini maka diperlukan pembelajaran petroleum system terutama source rock. Source rock yang memiliki potensi tinggi harus mempunyai kandungan kerogen yang cukup untuk dapat mengenerateminyak maupun gas ke perangkap-perangkap hidrokarbon disekitarnya.Dalam penelitian ini memaparkan aplikasi metode Passey dan untuk memetakan source rock dengan kandungan TOC yang berbeda-beda di setiap kedalaman dan responnya pada seismik inversi, kemudian dihitung potensinya sehingga didapat peta penyebaran source rock dan total hidrokarbon yang sudah tergenerate ke perangkap-perangkap struktur maupun yang masih tersisa di dalam source rock itu sendiri.Penelitian ini pun mengintegrasikan data geokimia, analisa petrofisika, dan teknik seismik inversi dalam mengkarakterisasi zona yang berpotensi. Tahapan awal eksplorasi dalam penentuan sweetspot adalah dengan menggunakan metode passey untuk menghasilkan data log pseudo TOC. Kedua, melakukan analisa petrofisika untuk mendapatkan parameter fisis yang sensitif pada formasi target.Ketiga adalah dengan mengaplikasikan seismik inversi Impedansi akustik (AI) untuk mengetahui persebaran batuserpih yang mengandung potensi gas berdasarkan nilai TOC dan parameter fisis yang sensitif pada formasi target.Keempat melakukan penghitungan sumber daya yang sudah tergenerate dan yang masih tersisa dalam tubuh shale sebagai source rock;Currently, the amount of available conventional gas and oil content are more limited while the amount of reserves has been decreased. Therefore we need an exploration of new resources, one solution is to expand the exploration of hydrocarbons by means of conventional or unconvensional, and to reduce the high failure in the exploration phase of the learning required for this petroleum system primarily source rock. Source rock that has high potential must have a sufficient content of kerogen to oil or gas can be generate to the hydrocarbon traps nearby. In this research exposes Passey Method and application method to map the source rock TOC content varies with each depth and seismic inversion, the response was then calculated its potential so obtained a map of the spread of source rock and hydrocarbon that already total generated to structures trap as well as those still remaining in the source rock itself. In this study integrates geochemical data, analysis of petrophysic, and seismic inversion technique to characterize potential zones. Early stages of exploration in the determination of sweetspot is using Passey Method to generate pseudo TOC. Second, petrophysical analysis to obtain physical parameters that are sensitive to the target formation. Third is by applying accustic impedance seismic inversion to determine the distribution of shale rock that contain gas potential based on the value of TOC and physical parameters that are sensitive to the target formation. Fourth do calculating resources have generated and remaining in a shale as source rock;Currently, the amount of available conventional gas and oil content are more limited while the amount of reserves has been decreased. Therefore we need an exploration of new resources, one solution is to expand the exploration of hydrocarbons by means of conventional or unconvensional, and to reduce the high failure in the exploration phase of the learning required for this petroleum system primarily source rock. Source rock that has high potential must have a sufficient content of kerogen to oil or gas can be generate to the hydrocarbon traps nearby. In this research exposes Passey Method and application method to map the source rock TOC content varies with each depth and seismic inversion, the response was then calculated its potential so obtained a map of the spread of source rock and hydrocarbon that already total generated to structures trap as well as those still remaining in the source rock itself. In this study integrates geochemical data, analysis of petrophysic, and seismic inversion technique to characterize potential zones. Early stages of exploration in the determination of sweetspot is using Passey Method to generate pseudo TOC. Second, petrophysical analysis to obtain physical parameters that are sensitive to the target formation. Third is by applying accustic impedance seismic inversion to determine the distribution of shale rock that contain gas potential based on the value of TOC and physical parameters that are sensitive to the target formation. Fourth do calculating resources have generated and remaining in a shale as source rock, Currently, the amount of available conventional gas and oil content are more limited while the amount of reserves has been decreased. Therefore we need an exploration of new resources, one solution is to expand the exploration of hydrocarbons by means of conventional or unconvensional, and to reduce the high failure in the exploration phase of the learning required for this petroleum system primarily source rock. Source rock that has high potential must have a sufficient content of kerogen to oil or gas can be generate to the hydrocarbon traps nearby. In this research exposes Passey Method and application method to map the source rock TOC content varies with each depth and seismic inversion, the response was then calculated its potential so obtained a map of the spread of source rock and hydrocarbon that already total generated to structures trap as well as those still remaining in the source rock itself. In this study integrates geochemical data, analysis of petrophysic, and seismic inversion technique to characterize potential zones. Early stages of exploration in the determination of sweetspot is using Passey Method to generate pseudo TOC. Second, petrophysical analysis to obtain physical parameters that are sensitive to the target formation. Third is by applying accustic impedance seismic inversion to determine the distribution of shale rock that contain gas potential based on the value of TOC and physical parameters that are sensitive to the target formation. Fourth do calculating resources have generated and remaining in a shale as source rock]"

"ABSTRAKEksplorasi dan produksi minyak dan gas bumi migas di Indonesia sampai sekarang masih terfokus pada migas konvensional dibandingkan migas nonkonvensional seperti hidrokarbon serpih. Hidrokarbon serpih adalah salah satu sumber energi migas yang terdapat di batuan induk memiliki material organik yang kaya dan telah mencapai kematangan, pada kondisi dan tipe tertentu dapat berfungsi sebagai reservoar minyak dan gas. Formasi Talang Akar adalah batuan induk dari Cekungan Jawa Barat Utara, berpotensi sebagai sistem petroleum nonkonvensional. Pada penelitian ini diintegrasikan analisis geokimia batuan induk, sifat fisika batuan dan interpretasi seismik yang menjadi dasar untuk melihat hubungan kekayaan dan kematangan material organik serta pesebarannya sebagai potensi hidrokarbon serpih di Cekungan Jawa Barat Utara. Hasil analisis geokimia batuan induk pada Formasi Talang Akar didapat tingkat kekayaan materi organik berkisar antara 0.57 ndash;1.81 wt fair-good , jendela awal kematangan pada kedalaman 3200 m dan tipe kerogen II/III menghasilkan minyak dan gas. Analisis sifat fisik batuan meliputi perhitungan Vshale, porositas, saturasi dan perhitungan TOC secara kontinu menggunakan Metode Passey untuk mengetahui nilai TOC pada setiap kedalaman pada Formasi Talang Akar. Hasil analisis selanjutnya adalah melakukan interpretasi seismik dengan metode inversi impedansi akustik model based untuk melihat persebaran batuan serpih dengan nilai 32000 ndash;54000 ft/s g/cc, arah penyebaran batuan serpih sebagai potensi hidrokarbon serpih berada di barat dan barat laut daerah penelitian. Kata Kunci:. Eksplorasi dan Produksi Migas, Hidrokarbon Serpih, Material Organik, Formasi Talang Akar, Geokimia Batuan Induk, Sifat Fisika Batuan, Inversi Seismik Impedansi Akustik

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ABSTRACTShale Hydrocarbon Analysis Based on Geochemical and Seismic Data in Northwest Java BasinAbstract Hydrocarbon exploration and production in Indonesia until now still focused on conventional energy rather than unconventional energy, which is shale hydrocarbon. Shale hydrocarbon is one of energy which contained in source rock that has high organic richness and been reached, in specific condition could be reservoir rock. Talang Akar Formation is source rock of Northwest Java Sedimentary Basin. This research was conducted on the integration of the three methods including organic geochemical analysis, seismic interpretation and petrophysics which became the basis for the wealth of organic material see the relationship and maturity of organic material also the distribution on the potential of shale hydrocarbon in the region. The analysis of Organic Geochemistry in Talang Akar Formation obtained the level of wealth of organic matter ranged from 0.57 ndash 1.81 wt fair good , the initial maturity of the window at a depth of 3200 m and category II III kerogen type produces oil and gas. The analysis of petrophysics which include calculation of TOC based on Passey Method continuously, the results of the analysis of this petrophysics validated with the value of the laboratory analysis. The next step is doing seismic interpretation with acoustic impedance inversion method to see the spread of the shale rocks with a value 32000 ndash 54000 ft s g cc, the direction of spread of shale rocks as shale hydrocarbon potential in the West and Northwest areas of research area. Keyword Hydrocarbon exploration, unconventional energy, geochemical, shale hydrocarbon, Organic Geochemistry, Talang Akar Formation, Acoustic Impedance Seismic Inversion."

"ABSTRAKPenelitian ini memberikan perspektif baru mengenai mekanisme pembentukan Cekungan Sumatera Utara, karena penelitian sebelumnya masih melihat Sesar Malaka sebagai sesar yang berperan dalam pembentukannya. Data yang digunakan dalam penelitian ini adalah peta gaya berat, peta konfi gurasi batuan dasar, data seismik dan data sumuran. Cekungan Sumatera Utara dapat dibagi menjadi dua (2) sub-cekungan yaitu: Sub-Cekungan Bagian Utara dan Sub-Cekungan Bagian Selatan. Sub-Cekungan Bagian Utara, dalam, diendapkan batuan sedimen serpih Paleogentebal, mengalami percepatan gravitasi rendah serta nilai alir bahang kecil seperti di Rendahan Arun. Sebaliknya, di Sub-Cekungan Bagian Selatan, dangkal, batuan serpih Paleogen relatif tipis tetapi mengalami percepatan gravitasi tinggi serta nilai alir bahangnya tinggi, sehingga berpotensi sebagai batuan induk gas serpih. Sub-Cekungan Bagian Selatan (Dalaman Tamiang) mengalami tektonik intensif. Penelitian mengenai proses sedimentasi, tektonik, dan analisis geokimia dapat menentukan konsep eksplorasi potensi gas serpih di Cekungan Sumatera Utara."

"Penelitian ini melakukan identifikasi lapisan shale gas menggunakan Inversi Impedansi Akustik dan Dekomposisi Spektral. Penelitian dilakukan di Lapangan "AP", Cekungan Barito dan formasi target yaitu Formasi Tanjung. Nilai Total Organic Carbon (TOC) ditentukan dengan menggunakan Passey's Number dan data geokimia. Selanjutnya, zona shale gas ditentukan dengan mengorelasikan Log Gamma-ray dengan Log Densitas, Sonic, NPHI, dan Resistivitas pada dua sumur. Hasil korelasi menunjukkan terdapat zona shale gas pada masing-masing sumur, yaitu dikedalaman 7130-7370 ft (Sumur A-1) dan 3100-3280 ft (Sumur P-1). Zona shale gas Sumur A-1 dan Sumur P-1 memiliki TOC rata-rata 5.4 wt% dan 2.8 wt%. Hasil tersebut didukung oleh hasil inversi impedansi akustik (AI) yang menujukkan nilai impedansi rendah untuk zona shale gas antara 5000-8000 m/s*g/cc (Line A-1), dan 7200-8900 m/s*g/cc (Line P-1). Selain itu, hasil tersebut juga didukung oleh hasil dekomposisi spektral yang menunjukkan anomali Continuous Wavelet Transform (CWT) tinggi pada frekuensi 18 Hz (untuk Line A-1) dan 20 Hz (untuk Line P-1). Analisis terintegrasi antara data seismik, hasil inversi AI dan CWT menunjukkan terdapat daerah potensial shale gas pada punggungan antilkin di Line A-1 dan Line P-1.

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This study identify shale gas layer using acoustic impedance (AI) and spectral decomposition. The object of this study is Field ‘AP’, Barito Basin, and the formation target is Tanjung Formation. Total Organic Carbon (TOC) values was determined using Passey’s Number and geochemical data. Furthermore, shale gas zone was determined by correlating Gamma-ray log with Density, Sonic, NPHI and Resistivity log in two wells.

Correlation result showed there are a shale gas zone in each well, which is at 7130-7370 ft (Well A-1) and 3100-3280 ft (Well P-1). Shale gas zone Well A-1 and P-1 has average TOC of 5.4 wt% and 2.8 wt%. These results are supported by calculation of AI inversion, which showed a low impedance values for shale gas zone between 5000-8000 m/s*gr/cc (Line A-1) and 7200-8900 m/s*gr/cc (Line P-1).

Besides, spectral decomposition also showed high CWT anomaly at 18 Hz (Line A-1) and 20 Hz (Line P-1). Integrated analysis of seismic data, AI, and CWT indicates there are potentials area of shale gas on the anticline ridge on Line A-1 and Line P-1."