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"[Inversi seismik deterministik telah dilakukan dengan menggunakan data PSTM di Lapangan Coki, Cekungan Kutai. Konsentrasi dari studi ini adalah zona Utama dengan kedalaman kurang lebih 3 km yang merupakan zona dengan akumulasi gas terbanyak. Tujuan utama dari penelitian ini adalah untuk mengidentifikasi ekstensidari batupasir di Zona Utama dengan menggunakan metode klasifikasi lithoseismic berdasarkan input dari hasil inversi seismik deterministik mengingat kontribusi seismik untuk pengembangan zona Utama sangat kecil sebelumnya dikarenakanresolusi yang terbatas. Studi kelayakan fisika batuan menunjukkan bahwa untuk Zona Utama, kandungan fluida gas dan air sudah tidak bisa dipisahkan lagi di crossplot P-Impedance vsPoisson’s Ratio.Sedangkan untuk pemisahan litologi batupasir dan batulempung secara umum masih bisa dipisahkan terutama untuk batupasir dengan kualitas bagus. Dengan menggunakan cube P-Impedance dan Poisson’s Ratio hasil seismik inversi sebagai input, klasifikasi lithoseismic dilakukan untuk memisahkanbatupasir dan batulempung. Hasil akhir dari proses ini adalah sand probability cube. Sand probability cube ini selanjutnya diinterpretasi dan digunakan untuk memprediksi ekstensi dari sand di zona Utama. Hasil interpretasi menemukan beberapa target baru di daerah dimana tidak ada kontrol dari sumur dan amplitudoseismic tidak menunjukkan karakteristik khusus. Berdasarkan hasil interpretasi ini optimalisasi trayektori dan desain beberapa sumur dilakukan.

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Deterministic seismic inversions were performed using PSTM (Pre-stack time migration) data in the Coki field, Kutai Basin. The study concentrated on the Peciko Main Zone (~3 km burial depth) which is the main gas producing interval of the field.

The main objectives of this project were to identify and map sand and possibly to define new targets for future development wells. Until 2012, seismic data had little contribution to well planning for this interval since their resolutions are poor and the seismic images only show the thick packages of stacked reservoirs. A rock physics feasibility study on P-impedancevs. Poisson’s Ratio crossplot showed that water and gas sands overlap each other significantly, meanwhile sand are discriminated from shale in particular for good quality sand. Lithoseismic classification is done using inverted P-impedance and Poisson’s Ratio to discriminate sand from shale. The final result is sand probability cube. Sand probability cube is then interpreted and used to define possible extension of sand limit for Main Zone.The final interpretation discovered several new targets where there is no well control and the seismic amplitudes didn’t show any distinctive characteristics. Then well trajectories are optimized using defined sand extension in

order to better target the reservoir.;Deterministic seismic inversions were performed using PSTM (Pre-stack time

migration) data in the Coki field, Kutai Basin. The study concentrated on the Peciko

Main Zone (~3 km burial depth) which is the main gas producing interval of the field.

The main objectives of this project were to identify and map sand and possibly to

define new targets for future development wells. Until 2012, seismic data had little

contribution to well planning for this interval since their resolutions are poor and the

seismic images only show the thick packages of stacked reservoirs.

A rock physics feasibility study on P-impedancevs. Poisson’s Ratio crossplot showed

that water and gas sands overlap each other significantly, meanwhile sand are

discriminated from shale in particular for good quality sand. Lithoseismic

classification is done using inverted P-impedance and Poisson’s Ratio to discriminate

sand from shale. The final result is sand probability cube.

Sand probability cube is then interpreted and used to define possible extension of

sand limit for Main Zone.The final interpretation discovered several new targets

where there is no well control and the seismic amplitudes didn’t show any distinctive

characteristics. Then well trajectories are optimized using defined sand extension in

order to better target the reservoir.;Deterministic seismic inversions were performed using PSTM (Pre-stack time

migration) data in the Coki field, Kutai Basin. The study concentrated on the Peciko

Main Zone (~3 km burial depth) which is the main gas producing interval of the field.

The main objectives of this project were to identify and map sand and possibly to

define new targets for future development wells. Until 2012, seismic data had little

contribution to well planning for this interval since their resolutions are poor and the

seismic images only show the thick packages of stacked reservoirs.

A rock physics feasibility study on P-impedancevs. Poisson’s Ratio crossplot showed

that water and gas sands overlap each other significantly, meanwhile sand are

discriminated from shale in particular for good quality sand. Lithoseismic

classification is done using inverted P-impedance and Poisson’s Ratio to discriminate

sand from shale. The final result is sand probability cube.

Sand probability cube is then interpreted and used to define possible extension of

sand limit for Main Zone.The final interpretation discovered several new targets

where there is no well control and the seismic amplitudes didn’t show any distinctive

characteristics. Then well trajectories are optimized using defined sand extension in

order to better target the reservoir.;Deterministic seismic inversions were performed using PSTM (Pre-stack time

migration) data in the Coki field, Kutai Basin. The study concentrated on the Peciko

Main Zone (~3 km burial depth) which is the main gas producing interval of the field.

The main objectives of this project were to identify and map sand and possibly to

define new targets for future development wells. Until 2012, seismic data had little

contribution to well planning for this interval since their resolutions are poor and the

seismic images only show the thick packages of stacked reservoirs.

A rock physics feasibility study on P-impedancevs. Poisson’s Ratio crossplot showed

that water and gas sands overlap each other significantly, meanwhile sand are

discriminated from shale in particular for good quality sand. Lithoseismic

classification is done using inverted P-impedance and Poisson’s Ratio to discriminate

sand from shale. The final result is sand probability cube.

Sand probability cube is then interpreted and used to define possible extension of

sand limit for Main Zone.The final interpretation discovered several new targets

where there is no well control and the seismic amplitudes didn’t show any distinctive

characteristics. Then well trajectories are optimized using defined sand extension in

order to better target the reservoir., Deterministic seismic inversions were performed using PSTM (Pre-stack time

migration) data in the Coki field, Kutai Basin. The study concentrated on the Peciko

Main Zone (~3 km burial depth) which is the main gas producing interval of the field.

The main objectives of this project were to identify and map sand and possibly to

define new targets for future development wells. Until 2012, seismic data had little

contribution to well planning for this interval since their resolutions are poor and the

seismic images only show the thick packages of stacked reservoirs.

A rock physics feasibility study on P-impedancevs. Poisson’s Ratio crossplot showed

that water and gas sands overlap each other significantly, meanwhile sand are

discriminated from shale in particular for good quality sand. Lithoseismic

classification is done using inverted P-impedance and Poisson’s Ratio to discriminate

sand from shale. The final result is sand probability cube.

Sand probability cube is then interpreted and used to define possible extension of

sand limit for Main Zone.The final interpretation discovered several new targets

where there is no well control and the seismic amplitudes didn’t show any distinctive

characteristics. Then well trajectories are optimized using defined sand extension in

order to better target the reservoir.]"

"Studi pengembangan studi tentang reservoar hidrokarbon merupakan suatu kajian untuk mengetahui karakteristik reservoar, yang nantinya dapat digunakan untuk beberapa hal, salah satunya untuk memperhitungkan cadangan hidrokarbon dari suatu area penghasil migas. Berdasar pada informasi yang didapat, baik data geologi setempat, data survey seismik, data sumur pemboran, dan beberapa parameter lainnya yang kemudian dapat menjadi satu kesatuan untuk mengetahui karakteristik dari suatu reservoar. Pada studi telah dilakukan pemodelan litofasies yang di konstrain dengan hasil inversi impedansi akustik pada lapangan "X" Cekungan Kutai. Hasil analisis sensitivitas menunjukan batupasir memiliki nilai impedansi akustik 4500-6500 (m/s)*(g/cc). Pemodelan litofasies dilakukan dengan memasukan hasil inversi impedansi akustik didapatkan hasil persebaran batupasir pada arah barat-timur dari area penelitian.

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Development study of hydrocarbon reservoar is study to understand the characteristic of reservoar, that will be used for several purposes. One of the aspects is to calculate the hydrocarbon reserve from oil and gas field. By Integrations among information from geological data, seismic survey, wellbore data and other parameter we can get the characteristic from reservoar.

Lithofacies modeling constrained by seismic inversion has been done on "X" field, Kutai Basin. Sensitivity analysis shows that sandstone has acoustic impedance value 4500-6500 (m/s)*(g/cc). Lithofacies modeling constrained by seismic inversion shows sandstone distribution to the west-east."

"Metode seismik merupakan suatu metode geofisika yang hingga saat ini merupakan metode dipercaya dapat memberikan gambaran bawah permukaan dari suatu lapangan. Seismik inversi adalah salah satu dari banyak metode yang digunakan untuk karakterisasi reservoar. Dengan menggunakan inversi seismik simultan mampu mendapatkan jawaban yang lebih pasti dengan cara menganalisa impedansi P, impedansi S dan densitas. Lapangan X, pada zona dangkal merupakan zona produksi yang cukup menjanjikan. Sehingga, pengembangan pada zona ini cukup gencar. Namun, beberapa kali prediksi reservoar meleset dikarenakan lapisan coal yang melimpah. Sebelum melakukan analisa inversi seismik simultan, perlu diketahui terlebih dahulu hubungan sifat fisik batuan (Zp, Zs, VpVs, lamda-rho dan mhu-rho) dengan properti batuannya (densitas dan porositas). Studi kelayakan dilakukan dengan cara melakukan cross plot parameter fisik batuan untuk dapat mendefinisikan litologi dan fluida yang ada. Selanjutnya well-seismic tie dilakukan untuk mendapatkan korelasi dan koherensi antara data dari log sumur dengan data seismik. Interpretasi horison, struktur dan pembuatan model frekuensi rendah dilakukan untuk memahami keadaan geologi dari daerah penelitian. Pada akhirnya, inversi seismik simultan dapat dilakukan dengan tepat. Hasil dari analisa inversi seismik simultan adalah kisaran nilai Zp, Zs dan Dn untuk mengkarakterisasi reservoar. Selain itu, analisa mengenai LMR (lamda-mhurho) juga dilakukan untuk mendapatkan hasil yang lebih baik. Sehingga, persebaran reservoar pada daerah penelitian dapat diketahui.

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Seismic is one of the methods in geophysics that until now still reliable for sub-surface imaging and interpretation of a field. Seismic inversion is one of the methods to characterize the reservoir. Using simultaneous seismic inversion, analyzing the P-impedance, S-impedance and density can be more convenient and certain.

X Field, especially in the shallow zone is a promising production zone. Hence, development in this zone is very incentive. Unfortunately, miss prediction sometimes happens due to coal layer that abundant. Relationship between rock physic (Zp, Zs, Vp/Vs, lamda-rho and mhu-rho) and rock property (density and porosity) must be understood prior to simultaneous seismic inversion analysis. Feasibility study was conducted by cross plotting among some parameters to define the lithology and fluids.

Well-seismic tie was conducted to have a good correlation and coherency between well-log data and seismic data. Horizon, structural interpretation and low frequency model were performed to have geological understanding of research area. The result of series steps previously then analyzed to have a good quality data. Eventually, the simultaneous seismic inversion can be performed in a proper way.

Result of the simultaneous seismic inversion analysis is a value of Zp, Zs and Dn for reservoir characterization. Moreover, LMR (lamda-mhu-rho) analysis can be performed to give more preferable result. Eventually, the distribution of gas-sand reservoir can be understood."

"Melalui metode inversi seismik yang digabungkan dengan simulasi geostatistik diperoleh suatu gambaran yang lebih rinci mengenai karakter reservoar pada lapangan "X", Cekungan Kutai dibandingkan dengan metode inversi seismik secara deterministik baik secara lataeral maupun vertikal. Proses inversi terlebih dahulu dilakukan kemudian dilanjutkan proses simulasi geostatistik untuk menghasilkan kemungkinan-kemungkinan terbaik model sebaran properti lapisan zona target disesuaikan dengan kondisi geologi lapangan dan mendekati batasanbatasan data yang dimiliki. Analisa variogram terhadap sebaran data lateral maupun horizontal memerlukan pengerjaan khusus terkait isotropik dan anisotropik. Untuk pendekatan geostatistik inversi pada lapangan "X" Cekungan Kutai diperoleh sebaran data impedansi akustik dengan resolusi vertikal yang lebih baik dibandingkan hasil dari inversi biasa, walaupun secara statistik tidak nampak perbedaan. Simulasi probabilitas sebaran batu pasir terhadap hasil geostatistik inversi diperoleh sebagai hasil terbaik dari beberapa kemungkinankemungkinan yang ada.

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Seismic inversion methods was combined with geostatistical simulation to obtain a more detailed picture of the characteristic of the reservoir on the field "X", Kutai Basin compared with the seismic inversion methods deterministically both lateral and vertically. Inversion process first made and then continued with geostatistical simulation process to produce the best possibilities layer property distribution models tailored to the target zone of the geological conditions of the field and approached the limits of data held.

Variogram analysis of the lateral and horizontal distribution of the data requires special processing adjustment associated to isotropic and anisotropic. For geostatistical inversion approach on the field "X" Kutai Basin acoustic impedance data obtained distribution with better vertical resolution than the result of the usual inversion, although the difference was not statistically visible. Simulating the probability distribution of sandstone on the results of geostatistical inversion was obtained as the best result of several possibilities exist."

"Lapangan ALIA yang berada di Delta Mahakam, Cekungan Kutai, Kalimantan Timur terdiri lebih dari 550 akumulasi reservoar yang secara struktur saling menumpuk dan terkompartemenkan. Lapangan ini sudah menghasilkan minyak kurang lebih selama 40 tahun. Terdapat lebih dari 400 sumur yang sudah di bor pada lapangan ini. Selama ini eksplorasi mengandalkan data sumur dan baru pada tahun 2011 dilakukan survey seismik 3D. Berdasarkan hasil survey seismik 3D tersebut, tesis ini memanfaatkan data seismik untuk karaktrerisasi reservoar lebih detail dengan menggunakan metode AVO dan Inversi Simultan. Metode AVO dan Inversi Simultan digunakan untuk mengetahui pola dan anomali hidrokarbon dari penampang seismik. Metode ini akan menghasilkan beberapa sifat fisika properti reservoar seperti Impedansi gelombang P, Impedansi Gelombang S, densitas Dn, dan Lamda-rho. Hasil analisa pada lapangan ALIA menunjukan bahwa pada zona reservoar target yaitu Top R0-35 memiliki anomali pada Attribute AVO Intercept/A (-), Gradient/B (-), Product/A*B (+). Selain zona reservoar target, Zona reservoar lain juga memiliki pola anomali yang sama yaitu pada Top Horizon R0-1. Hasil analisa Inversi simultan juga menunjukan bahwa zona reservoar tersebut memiliki anomali hidrokarbon dengan nilai Impedansi P (Zp) antara 2000 - 4000 ms-1gcc-1, nilai Impedansi S (Zs) berkisar antara 900 - 2050 ms-1gcc-1, dan Densitas (Dn) berkisar antara 1.7-2.11 gcc. Lambda Rho juga memiliki anomali yang sama dengan nilai berkisar antara 8.8-14.6 Gpa*g/cc.

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ALIA field is located in Kutai basin, Mahakam Delta East Kalimantan, comprises of over 550 unconnected accumulations/reservoirs in structurally stacked and compartementalized deltaic sands. It has produced oil and gas for 40 years and more than 400 wells have been drilled in the field. Exploration and Development of this field was rely on well data and 3D seismic survey just conducted on 2011. Based on 3D seismic result, this thesis utilize seismic data for reservoar characterization by using AVO analyses and Simultaneous Inversion to get more detail of results.

Simultaneous inversion and AVO analyses is novel method in reservoir characterization. The method will produce several physical properties of reservoir such as P-wave Impedance, S-wave Impedance, density, Vp/Vs ratio, Lamda-rho and mu-rho. These physical properties could be used to estimate the type and content of reservoir lithology. Simultaneous AVO inversion needs P-wave sonic log, S-wave sonic log and density as input.

Analyses result from ALIA field at reservoar target zone, at Top R0-35 having the anomaly AVO Intercep/ A (-), Gradient B (-) and Product A*B (+). Another reservoar zone also having the same anomaly at Top Horizon R0-1. Simultaneous Inversion result also showed hydrocarbon anomaly with Impedance P (Zp) value around 2000 - 4000 ms-1gcc-1, Impedance S (Zs) around 900 - 2050 ms-1gcc-1, and Density (Dn) around 1.7-2.11 gcc. Lambda Rho showed hydrocarbon anomaly with value around 8.8-14.6 Gpa*g/cc"

"Skripsi ini membahas tentang metode vertical seismic profiling (VSP) dan aplikasinya dalam karakterisasi reservoar. VSP merupakan pengukuran seismik yang dilakukan dengan menempatkan receiver di lubang bor. Karakter reservoar yang akan diteliti yaitu batu pasir pada lapangan Sejati, yang merupakan salah satu lapangan minyak dan gas VICO Indonesia yang terletak di Cekungan Kutai, Kalimantan Timur. Data yang tersedia dalam penelitian ini yaitu data VSP (near & far offset) dan well log dari satu sumur eksplorasi. Karakterisasi reservoar berdasarkan metode inversi data VSP. Langkah-langkah pengerjaan yaitu crossplot, correlation, picking horizon, initial model, inversion analysis (QC), dan final inversion. Dari hasil inversi memperlihatkan adanya sebaran impedansi rendah pada zona target. Karena besarnya tuning thickness maka perlu dilakukan studi lebih lanjut untuk memastikan apakah impedansi rendah tersebut mengindikasikan lapisan sand atau bukan.

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This study are about vertical seismic profiling (VSP) and it?s application for reservoir characterization. VSP is an seismic measurement which is put some receivers in borehole. The character of reservoir will be studied is sandstone in Sejati field, which is one of VICO?s oil and gas fields at Kutai Basin, East Kalimantan. The data avalaible of this study are VSP (near & far offset) and well log from one exploration well. Reservoir characterization based on VSP inversion method. The sequence step of this study are crossplot, correlation, picking horizon, initial model, inversion analysis (QC), and final inversion. The inversion result show low impedance at target zone. Because tuning thickness is very high, so it is needed detailed study for identifying sand distribution at target zone."

"Penelitian ini akan membahas mengenai pemodelan penyebaran fasies sedimen laut dalam di salah satu lapangan yang mengandung gas di Cekungan Kutai. Fasies pengendapan di lapangan Y dibagi menjadi 5 yakni Channel Axis, Channel Margin, Levee Overbank, Mass Transport dan Mud. Fasies pengendapan tersebut dibedakan satu dengan yang lain dalam penelitian ini melalui perbedaan cut-off vshale dan pola log GR. Korelasi antar sumur menggunakan ketentuan stratigrafi sikuen dibantu dengan data plot gradien tekanan dan data seismik. Interpretasi data seismik 3D pada interval pemodelan yaitu interval A bertujuan untuk membentuk kerangka pemodelan penyebaran fasies. Pemodelan penyebaran fasies pada penelitian kali ini menggunakan metode Multi Point Statistic Simulation (MPS). Modul pemodelan MPS dalam software Petrel menyediakan sarana untuk menyertakan berbagai macam input data geologi dan geofisika dalam pemodelan fasies. Data input tersebut antara lain training image, seismik vshale dan data peta medan azimuth. Penelitian ini juga mencoba membandingkan proses pemodelan fasies menggunakan metode MPS dengan salah satu metode stochastic lainnya yakni SIS (Sequential Indicator Simulation).

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This study describes about fasies distribution modeling of deepwater deposit in one of gas field at Kutai Basin.The deepwater depositional fasies in Y field can be divided into 5 fasies such as Channel Axis, Channel Margin, Levee Overbank, Mass Transport and Mud. Vshale cut-off and GR log pattern are used for dividing one depositional fasies to other depositional facies. Sequence stratigraphy concept is applied on well to well correlation supported with other data like pressure gradien plot and seismic section. 3D seismic horizon interpretation at A interval aim to build model framework for fasies distribution.

This research utilizes Multi Point Statistic Simulation (MPS) method to distribute the fasies. The MPS modeling modul in Petrel provides some options to use geology and geophysics data as modeling input. Thoose input data are training image, vshale seismic cube and azimuth field map. The study also tried to compare the facies modeling process using the MPS method with one of the other stochastic methods namely SIS ( Sequential Indicator Simulation )."

"Cekungan Sumatera Selatan merupakan salah satu cekungan utama penghasil minyak dan gas bumi di Indonesia. Lapangan “X” pada Cekungan Sumatera Selatan merupakan salah satu lapangan yang memiliki reservoar hidrokarbon. Penelitian ini berfokus pada zona target Lower Talang Akar Formation (LTAF) pada Sumur G-46, G-47, dan G-49. Pada penelitian ini, penentuan sebaran litologi batupasir dilakukan menggunakan metode seismik inversi post-stack model based serta properti petrofisika. Inversi seismik model based dilakukan untuk menghasilkan nilai impedansi akustik. Properti petrofisika pada penelitian ini meliputi volume shale, porositas, dan saturasi air. Reservoar pada daerah penelitian ini memiliki litologi shaly sand sehingga digunakan metode pengukuran saturasi air persamaan Indonesian dan porositas menggunakan parameter neutrondensity. Berdasarkan hasil analisis petrofisika, zona reservoar LTAF memiliki prospek hidrokarbon dari reservoar yang baik dengan nilai porositas efektif berkisar 18%-25%, nilai saturasi air berkisar 23%-42%. Analisis petrofisika diakhiri dengan analisis lumping, di mana menghasilkan net reservoir dan net pay. Berdasarkan hasil analisis sensitivitas – analisis yang ditunjukkan untuk memisahkan litologi sand dan shale, nilai impedansi akustik tidak dapat memisahkan litologi sand dan shale karena sand bersifat tight. Inversi seismik model based menghasilkan rentang nilai impedansi akustik berkisar 7000 ((m/s)*(g/cc)) – 10500 ((m/s)*(g/cc)). Berdasarkan hasil inversi, nilai impedansi akustik tidak dapat memisahkan litologi sand dan shale karena ketebalan lapisan reservoar sand yang sangat tipis berkisar 10-20 ft.

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The South Sumatra Basin is one of the main oil and gas producing basins in Indonesia. Field "X" in the South Sumatra Basin is one of the fields that has a hydrocarbon reservoir. This research focuses on the Lower Talang Akar Formation (LTAF) target zone in Wells G-46, G-47, and G-49. In this study, determining the distribution of sandstone lithology was carried out using the post-stack model based seismic inversion method and its petrophysical properties. Model based seismic inversion is performed to produce acoustic impedance values. Petrophysical properties in this study include shale volume, porosity, and water saturation. The reservoir in this study area has a shaly sand lithology so that the Indonesian equation of water saturation and porosity measurement methods are used using the neutron-density parameter. Based on the results of petrophysical analysis, the LTAF reservoir zone has good prospects for hydrocarbons from the reservoir with effective porosity values ranging from 18% -25%, water saturation values ranging from 23% -42%. The petrophysical analysis ends with a lumping analysis, which produces a net reservoir and net pay. Based on the results of the sensitivity analysis - the analysis shown to separate sand and shale lithology, the acoustic impedance value cannot separate sand and shale lithology because sand is tight. Model based seismic inversion produces a range of acoustic impedance values ranging from 7000 ((m/s)*(g/cc)) – 10500 ((m/s)*(g/cc)). Based on the inversion results, the acoustic impedance value cannot separate the lithology of sand and shale because the thickness of the reservoir sand layer is very thin, ranging from 10-20 ft."

"Lapangan Delta di Mahakam cekungan lower Kutai yang sekarang dioperasikan oleh Chevron Indonesia Company telah berproduksi sejak tahun 1975. Produksi dari lapangan ini mencapai puncak produksi sebesar 31 MBO pada tahun 1991, kontribusi terbesar dari produksi tersebut berasal dari zona low resistivity. Berdasarkan data log, zona yang menghasilkan hidrokarbon biasanya terdapat pada zona yang menunjukkan nilai resistivitas yang tinggi, tetapi pada lapangan Delta yang menjadi area penelitian ini sebagian besar produksi didominasi dari zona yang mempunyai nilai resistivitas yang rendah. Berdasarkan hasil analisa menunjukkan bahwa nilai tersebut dipengaruhi oleh beberapa faktor, diantaranya keberadaan mineral pyrite (Fes2), dominasi persentase volume clay dan ketebalan pay zone, dan nilai salinitas yang lebih tinggi dibandingkan dengan zona hidrokarbon yang mempunyai nilai resistivitas yang lebih tinggi pada lapangan ini. Persentase nilai pyrite yang terdapat pada zona low resisivity ini hanya sebesar 1.2% - 3% dari volume batuan, tetapi nilai tersebut sudah bisa menurunkan nilai resistivitas sebesar 65% lebih rendah dibandingkan dengan zona hidrokarbon yang mempunyai nilai resistivitas yang tinggi pada formasi Deltaic dan Formasi Yakin. Persentase volume clay dan ketebalan juga mempengaruhi, dominasi mineral illite pada shale dan ketebalan kurang dari 5ft akan mempengaruhi penurunan nilai resistivity sebesar 10% dibandingkan high resistivity pay zone pada formasi Deltaic dan formasi Yakin. Dari analisa laboratorium pada air formasi menunjukkan bahwa pada zona low resistivity mempunyai nilai salinitas lebih tinggi 2000ppm diandingkan formasi Deltaic dan Formasi Yakin.

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Sepinggan Field in Lower Kutai Basin which is in Mahakam Block and operated by Chevron Pacific Indonesia has been produced since 1975. Hydrocarbon pay zone generally has high resistivity. Nevertheless, Sepinggan Field production is primarily from low resistivity zone which is the most contributors even for its peak production at 31 MBO in 1991. Analysis result shows that the low resistivity value of the zone is influenced by some factors. These factors are pyrite content (FeS2), clay volume percentage domination and pay zone thickness, and more saline than high resistivity pay zone salinity. Pyrite volume percentage in this low resistivity zone ranges from 1.2 to 3 %.

This value can reduce 65 % from the normal resistivity value of hydrocarbon zones from Deltaic and Yakin Formation in this field. Illite domination in clay mineral content and less than 5 ft thickness also can reduce 10 % from the normal resistivity value of Deltaic and Yakin. Formation pay zones Laboratory analysis of formation water shows that salinity of low resistivity zone has 2000 ppm higher than Deltaic and Yakin water formation salinities."

"ABSTRAKRepresentasi valid heterogenitas geologi merupakan masukan penting bagi model kuantitatif yang digunakan dalam mengelola kegiatan bawah permukaan. Dalam tubuh sedimen, distribusi fasies merupakan faktor penting heterogenitas geologi. Tiga pemodelan berbasis grid telah digunakan untuk membangun model numerik untuk distribusi fasies Formasi Missisauga, lapangan Penobscot yaitu Sequential Indicator Simulation, Truncated Gaussian Simulation dan Multi-point Geostatistics. Pemodelan berbasis variogram (Sequential Indicator Simulation, Truncated Gaussian Simulation), menghasilkan model yang memperhitungkan nilai-nilai data sumur dan korelasi spasial antar sumur tapi terlalu terbatas untuk menangkap geometri sebenarnya dari fasies disebabkan oleh fakta bahwa variogram hanya memodelkan kontinuitas spasial antara dua lokasi pada satu waktu. Multi-point Geostatistics, suatu pemodelan yang bebas variogram, menawarkan representasi yang lebih baik untuk heterogenitas geologi karena memungkinkan menangkap struktur dari training image dengan meminjam pola multi-point dari training image, untuk kemudian ‘ditanamkan’ pada data well-log, data seismik dan data produksi. Training-image yang digunakan dalam Multi-point Geostatistics tidak dapat dipilih secara sembarang karena tidak semua singkapan dapat dijadikan model training-image. Pengetahuan geologi yang komprehensif adalah kunci dari pemodelan Multi-point Geostatistics.

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ABSTRACTValid representation of facies distribution is an important input for quantitative models used in managing subsurface activities. Three grid-based algorithms have been employed to build models for sand distribution of Missisauga Formation, Penobscot Field for the test. Variogram-based techniques (Sequential Indicator Simulation and Truncated Gaussian Simulation) generate models that honor well data values and spatial correlation between the wells but they are limited to capture actual facies geometries due to the fact that variogram only models spatial continuity between two locations at a time. Multiple-point geostatistics, a variogram-free technique, offers better representation of geological heterogeneity since it allows capturing structure from so-called ‘training images’ by borrowing multiple-point patterns from the training image, then anchors them to subsurface well-log, seismic and production data. Nevertheless, the training image used in multiple-point geostatistics cannot be chosen arbitrarily, and that not all outcrops might be suitable for training image models. Comprehensive knowledge of geological heterogeneity is the key of a successful multiple-point facies modeling."