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Abstrak :
Method in calculating thickness changes of sedimentary layers caused by compaction (decompaction) has been developed to reconstruct geohistory of the basin accurately. Decompaction method which is used in this research proposed by Angevine et al (1987) and several input from other researchers such as Van Hinte (1978) and Perrier and Quiblier (1974) are also applied. Thickness changes calculation of sedimentary layers caused by compaction (dccompaction) is based on the reduction of porosity with depth and assuming volume of grain to be constant. Parameters which are needed in this calculation include trend of porosity reduction, initial thickness, ages, depth and compaction factor of sedimentary layers. Porosity reduction during burial is unique and different for lithology types with different depositional environment or facies. Grouping of layers based on depositional environment or facies is necessary to produce an accurate porosity trend of the layers. Case study of Q-1 Well, which is drilled in Kampar Block, Central Surnatera Area produced seven groups with different depositional environment or facies. Each group has different porosity trend for each lithology type (shale and sandstone or limestone). Geohistory analysis can be constructed accurately if thickness changes caused by compaction are known. This analysis is used to potray vertical movement of a stratigraphic horison as an indicator of subsidence and uplift history in the basin since the horison was deposited.

Abstrak :
Analisis burial geohistory merupakan salah satu bahan kajian dalam analisis cekungan secara kuantitatif yang terintegrasi selain thermal history dan analisis hydrocarbon generation. Data dasar yang dihasilkan berupa parameter tektonik sedimentasi yang kemudian digambarkan dalam bentuk rekonstruksi sejarah pemendaman. Selain itu akibat pembebanan sedimen, maka terjadi perubahan porositas dan permeabilitas yang berpengaruh terhadap aliran fluida dalam batuan. Sehingga arah migrasi dan keberadaan hidrokarbon di daerah penelitian dapat ditafsirkan. Perubahan proses sedimentasi yang terjadi di daerah penelitian dapat dikaji dari data di setiap sumuran. Pada awal pengendapan Formasi Belumai sampai dengan akhir pengendapan Formasi Baong Tengah (10,1 juta tahun lalu) terbentuk endapan transgresif. Sistem pengendapan tersebut ditandai dengan kecepatan sedimentasi yang lebih lambat dibanding kecepatan penurunan dasar sedimen. Endapan regresif terjadi sejak awal pengendapan Formasi Baong Atas yang ditandai percepatan sedimentasi sangat besar (4-5 kali kecepatan sebelumnya). Proses tersebut terjadi karena berkaitan dengan aktivitas tektonik Miosen Tengah, sedangkan batuan sumber berasal dari Bukit Barisan yang telah terangkat sejak 12 juta tahun lalu. Periode selanjutnya terjadi perlambatan sedimentasi tetapi sedimen masih regresif dan berakhir pada 4,5-4,8 juta tahun lalu (akhir pengendapan Formasi Seurula bagian bawah). Proses pengendapan yang terjadi sejak 17,8 juta tahun lalu tersebut di atas mengalami perpindahan pusat sedimentasi (depocentre) yang dikendalikan oleh aktifnya patahan regional. Batuan dasar paling dalam (depocentre) bergeser dari timur ke barat (tengah daerah penelitian) bersamaan dengan pengendapan Formasi Baong Atas. Sehingga formasi tersebut mempunyai ketebalan awal maksimum di bagian tengah daerah penelitian (775 m) (Sumur SW-5). Batuan dasar paling dalam di SW-5 tersebut berlangsung terus sampai sekarang, sehingga berpengaruh terhadap keberadaan hidrokarbon di sumur tersebut. Posisi Formasi Belumai yang menumpang di atas batuan dasar paling dalam telah menyebabkan berkurangnya porositas dan permeabilitas batuan, sehingga tidak memungkinkan adanya migrasi hidrokarbon ke SW-5. Seandainya hidrokarbon dapat terbentuk di bagian bawah formasi tentunya telah bermigrasi ke selatan. Hal ini disebabkan aliran fluida akibat kompaksi sangat berhubungan dengan faktor ekspulsi dan sangat berpengaruh terhadap proses diagenesa serta migrasi hidrokarbon. Faktor ekstensi kerak ternyata paling besar dijumpai di Sumur SW-6 (1,054) sedangkan sumur yang lain berkisar antara 1,01-1,03. Faktor ekstensi kerak tersebut hanya berpengaruh terhadap awal pembentukan cekungan di daerah penelitian, yaitu dengan terbentuknya depocentre di SW-6. Periode berikutnya deformasi tektonik lebih berpengaruh terhadap perubahan bentuk arsitektonik cekungan. Hal ini terbukti Sumur SW-5 yang menempati cekungan paling dalam sejak 9,6 juta tahun lalu faktor ekstensi keraknya lebih kecil dibanding SW-6. ......Burial geohistory analysis is one of the integrative method in quantitative basin analysis as same as thermal history and hydrocarbon generation analysis. The resulted data is sedimentation tectonic parameter which is displayed as burial geohistory reconstruction. Because of sedimentary loading, there was a change in porosity and permeability which were influence the fluidity flow in the rock. Therefore the migration pathway and hydrocarbon occurrence in the study area can be predicted. The sedimentary process changes in the study area can be assessed from the data in the well transgressive sediment was formed since the early time of Belumai Formation deposition until the end of Middle Baong Sedimentation (10.1 Million Years Ago). This depositional system was characterized by slower sedimentation rate than rate of base sedimentation subsidence. Regressive deposition took place in the early sedimentation of Upper Baong Formation characterized by huge sedimentary acceleration (4-5 times from previous rate). This process correlated with Middle Miocene tectonic activity. The source rocks came from the uplifted Barisan Mountain since 12 MYA. In the next period, reducing of sedimentation rate occurred and finished at 4.5 - 4.8 MYA (in the end of Lower Seurula Formation deposition), but the sediment was still in regressive phase. Centre of sedimentation (depocentre) of mentioned above sedimentation process began since 17.8 MYA, was moved from the original position. The movement was controlled by activation of regional fault. The deepest basement (depocentre) moved from East to West (middle part of study area), at the same time as deposition of the Upper Baong Formation. Therefore, this formation has early maximum thickness (775 m) in the middle part of the study area (SW-5 Well). The basement in SW-5 well is still the deepest in the study area until present-day. It influence the hydrocarbon occurrence in this well. The Belumai Formation which is immediately overlies the deepest basement has porosity and permeability decrease that made it was not possible for oil to migrated to SW-5 well. if the hydrocarbon could be generated by the lowest part of the Belumai Formation, it would migrated to the South. In this case because the fluidity flows as a result of compaction is very correlate with expulsion factor and strongly influence to diagenetic process and hydrocarbon migration. The highest value of crustal extension (1.054) is occurred in SW-6 Well,whilst in others wells are in range of 1.01 to 1.03. The crustal extension just influenced the early forming sedimentary basin in the study area. It influenced the depocentre in SW-6. In the next period, architectural form of sedimentary basin was more influenced by tectonic deformation. It is proved by the position of SW-5 (it's crustal extension value lower than SW-6) which occurred in the deepest part of the basin since 9,6 MYA.

Abstrak :
Metode litologi seismik bertumpu pada amplitudo gelombang-gelombang seismik yang dipantulkan oleh bidang batas antar lapisan. Litologi seismik menghasilkan penampang pseudosonic log, pseudo velocity atau impedansi akustik yang merepresentasikan litologi lebih baik dari pada seismik struktur. Amplitudo dari sinyal seismik terpantul tergantung pada variasi impedansi akustik yang merupakan hasil kali kecepatan dan densitas. Sehingga perubahan pada salah satu parameter tersebut, kecepatan atau densitas batuan akan berkontribusi pada variasi respon seismik dari reservoar. Litologi dan ketebalan reservoar serta sejumlah sifat petrofisika batuan seperti porositas dan saturasi fluida dipengaruhi kedua parameter tersebut. Oleh karena itu untuk mengestimasi sifat-sifat petrofisika batuan dengan menggunakan data seismik harus mengkuantisasi kontribusi masing-masing parameter petrofisika pada pengukuran akustik. Metoda ini digunakan untuk mengestimasi parameter petrofisika reservoar migas dari data seismik sehingga disebut sebagai 'Seismically guided reservoir characterization di luar sumur pengeboran. Geostatistik merupakan framework yang mengkombinasikan sample yang terdistribusi secara spatial, berdasarkan atas data log sumur dan data seismik. Yang berguna untuk estimasi yang akurat dari reservoar properties dari ketidakpastian dari model reservoar. Dalam geostatistik mapping teknik ini berdasarkan atas Kriging, Regresi Linear dan Cokriging untuk memberikan kontribusi berdasarkan informasi petrofisika batuan yang diperoleh dari log sumur dan arah spatial dari seismik attribute. Secara garis besar teknik geostatistik untuk mengkombinasikan informasi petrofisika dan data seismik. Dengan geostatistik pada situasi dengan minimal kontrol data, dapat memprediksi karakteristik reservoar dengan lebih baik dibandingkan dengan mapping standard.

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Seismic Lithology method was introduced in the 1970's was based on amplitude of the seismic waves reflected by the subsurface interfaces. Seismic lithology generates pseudo sonic log, pseudo velocity log or acoustic impedance time section which represents the lithology better than the seismic structure. By using this method it is possible to estimate the petrophysical properties of the reservoir rocks from seismic data. Furthermore it is possible to estimate the reservoir parameters from seismic data. This approach enables to implement a new method which referred to as seismically guided reservoir characterization in the zones outside the borehole. The amplitudes of reflected seismics signals depend primarily on variations in acoustic impedance. Changes in either rock velocity or density will contribute to variations in the seismic response of the reservoir. A number of petrophysical properties, such as porosity, fluid saturation affect both rock velocity and density. To estimate reservoir properties using seismic data it is necessary to quantify the respective contribution of each petrophysical parameter to the acoustic measurements. A series of laboratory P wave and S wave measurement has been conducted on limestone core samples from Baturaja limestone reservoir. By using the laboratory acoustic measurement data to support seismic derived porosity and fluid saturation determination in the reservoir. Several parameters have been derived from transit time data such as P and S wave velocities, Poisson ratio. To provide relationship between fluid saturation, porosity, P wave velocity and Poisson ratio, and modify acoustic impedance, crossplots between the parameters have been generated using a combination of laboratory acoustic measurement on core samples and mathematic modelling. A geostatistical technique integrating well and seismic data has been studied for mapping porosity in hydrocarbon reservoirs. The most important feature of the cokriging method is that it uses spatial correlation functions to model the lateral variability of seismic and porosity measurements in the reservoir interval. Cokriging was tested on a numerically simulated reservoir model and compared first with kriging, then with a conventional least squares procedure relying only on local correlation between porosity and acoustic impedance. As compared to kriging, the seismically assisted geostatistical method detects subtle porosity lateral variations that cannot be mapped from sparse well data alone. As compared to the standard least squares approach, cokriging provides not only more accurate porosity estimates that are consistent with the well data. Using seismically derived acoustic impedances, cokrigging also was applied to estimate the distribution of porosity in limestone reservoir.

Abstrak :
Tesis ini membahas karakterisasi oil shale Formasi Gumai dari data Sumur NBL-1, Lapangan Abiyoso, Sub Cekungan Jambi, Cekungan Sumatera Selatan dengan pemodelan oil yield dan elastisitas batuan. Karakterisasi batuan dilakukan dengan menganalisis sampel pengeboran inti (core) dari shale pada kedalaman 4266 - 4280 feet dan kedalaman 4283 - 4295 feet di laboratorium (petrografi, XRD, oil yield / Fischer Standard retort), %TOC, analisis, pyrolisis, kerogen type). Pemodelan oil yield dilakukan dengan membuat korelasi regresi linear antara data log (bulk density, log neutron, log sonik) dan data oil yield - % TOC dari sampel tersebut, sedangkan model elastisitas batuan dilakukan dengan pendekatan: kualitas medium (Q), rasio poisson, dan modulus Young. Analisis kualitas medium (Q) dilakukan dengan metode spectral magnitudo decay, sedangkan analisis modulus Young dan rasio Poisson diturunkan rumus dari Mavko, dkk. (2009). Hasil penelitian diperoleh karakteristik bahwa kedua lapisan tersebut dalam kategori oil shale dengan tipe Tasmanite, kerogen tipe II, dan jenis liptinite dalam kondisi belum matang, diendapakan pada lingkungan pengendapan laut dangkal dengan energi rendah (kedalaman 4266 - 4280 feet) dan laut dangkal relatif reduktif (kedalaman 4283 - 4295 feet) yang berbatasan dengan lingkungan darat. Model oil yield dari log bulk density pada kedalaman lapisan 4266 - 4280 feet: OYlog = -4,93x(log ρb) + 19,46 dan pada kedalaman lapisan oil shale 4283 - 4295 feet: OYlog= -6,03 x(log ρb) + 23,58. Model oil yield log neutron hanya berhasil dilakukan pada kedalaman 4283 - 4295 feet: OYlog = 7,93x(log ФNPHI)+ 4,30, sedangkan model oil yield log neutron tidak berhasil pada lapisan oil shale yang pertama. Model kualitas batuan (Q) dihasilkan 120 - 129, modulus Young, dan rasio Poisson tidak berhubungan dengan variasi oil yield. Potensi oil shale yang dihasilkan dari kedua lapisan tersebut berkisar 7 galon/ton dan tidak berpotensi sebagai reservoar shale. Potensi oil shale Formasi Gumai di daerah penelitian lebih kecil daripada oil shale yang telah diproduksikan di Formasi Green River, Amerika Serikat yang mencapai 20 - 30 galon per ton. ......The thesis learned oil shale characterization on Gumai Formation, Well NBL-1, Abiyoso Field, Jambi Sub Basin, South Sumatera Basin using oil yield and elasticity modeling. Characterization of the shale uses core and log data on the depth 4266 - 4280 feet and 4283 - 4295 feet. Methods that was used core description, geochemical, log correlation, and calculation of bore hole seismic. Result of the research got that the shale have been deposited at low energy shallow marine till land margin. The kerogen type is type II, liptinite, and immature. Model of oil yield of bulk density log on the depth 4266 - 4280 feet; OYlog = -4,93x(log ρb) + 19,46 and 4283 - 4295 feet: OYlog = 7,93x(log NPHI)+ 4,30. Sonic log model did not succeed on each shale layer, but neutron log just succeeded on the depth 4283 - 4295 feet. Elasticity model such attenuation (Q), modulus Young (E), Poisson ratio (σ) did not succeed. The oil shale potency is 7 - 9 gallon/ton on the depth 4266 - 4280 feet, while on the depth 4283 - 4295 feet is 8 - 9 gallon/ton. Generally, the oil shale have not been enough yet as shale reservoir, because micro crack for permeability was not. Potency of the oil shale is less than Green River Formation's oil shale in United Stated of America which have been produced till 20 ? 30 gal/ton.