Hasil Pencarian  ::  Simpan CSV :: Kembali

"[ABSTRAKFormasi Toolachee memiliki penyebaran yang sangat luas di Cekungan Cooper.Padahal ketebalan Formasi Toolachee tidaklah begitu tebal dengan rata-rataketebalan berkisar hingga 300 m. Proses sedimentasi Fm. Toolachee secararegional berupa fluvial (meandering) dengan urutan batuan berupa batupasir,batulempung, batulanau, dan batubara. Batupasir Fm. Toolachee memilikiporositas yang sedang hingga bagus, sehingga dapat bertindak sebagai reservoiryang terbukti mengalirkan gas pada Sumur Meranji-1. Dengan asumsi bahwapenyebaran Fm. Toolachee luas dan terendapkan di semua daerah penelitian,seharusnya ditemukan juga kandungan hidrokarbon pada dua sumur lainnya, yaituCooba-1 dan Pelican-5. Kenyataannya, Cooba-1 dan Pelican-5 tidak ditemukankehadiran hidrokarbon, sekalipun Fm. Toolachee masih terbentuk disana.Hipotesis yang diangkat adalah bahwa ada kontrol stratigrafi yang berpengaruhterhadap akumulasi hidrokarbon pada Fm. Toolachee. Dari hasil analisis sumurdan seismik yang dibantu dengan atribut seismik dan inversi seismik ditemukanadanya perubahan fasies pada zona reservoir di Meranji-1. Zona reservoir terlihattidak memiliki kemenerusan antara Meranji-1, Cooba-1 dan Pelican-5. Penelitianini menghasilkan penyebaran fasies secara lateral dan vertikal pada Fm.Toolachee. Oleh karena itu, sumur-sumur selanjutnya diharapkan mengikuti polapenyebaran fluvial dari batupasir zona target.

---

ABSTRACTToolachee Fm has widespread deposition which is formed widely in CooperBasin. Although, Toolachee Fm is thin bed formation with thickness averaging300-400m only. Sedimentation process in Toolachee Fm is controlled by fluvialsystem which is formed in meandering depositional environment with lithologyconsists of sandstone, shale, siltstone, and coal. Sandstone of Toolachee Fm hasmoderate to good porosity, therefor it can act as reservoir which is proven byflowing gas in Meranji-1 well. Based on assumption of widespread depositional ofToolachee Fm, hydrocarbon accumulation shall be found in two wells, Cooba-1and Pelican-5. In fact, Cooba-1 and Pelican-5 do not encounter significanthydrocarbon in Toolachee Fm. Hypotehsis were made that stratigraphy has animportant influence of hydrocarbon accumulation in Toolachee Fm. Study result,from integrated study well and seismic interpretation which is supported byseismic stratigraphy, attribute seismic and seismic inversion, show facies changein Toolachee resulting truncated sand body. This study produces a comprehensivefacies distribution both laterally and vertically. Therefor, next well should bedrilled along channel geometry, Toolachee Fm has widespread deposition which is formed widely in CooperBasin. Although, Toolachee Fm is thin bed formation with thickness averaging300-400m only. Sedimentation process in Toolachee Fm is controlled by fluvialsystem which is formed in meandering depositional environment with lithologyconsists of sandstone, shale, siltstone, and coal. Sandstone of Toolachee Fm hasmoderate to good porosity, therefor it can act as reservoir which is proven byflowing gas in Meranji-1 well. Based on assumption of widespread depositional ofToolachee Fm, hydrocarbon accumulation shall be found in two wells, Cooba-1and Pelican-5. In fact, Cooba-1 and Pelican-5 do not encounter significanthydrocarbon in Toolachee Fm. Hypotehsis were made that stratigraphy has animportant influence of hydrocarbon accumulation in Toolachee Fm. Study result,from integrated study well and seismic interpretation which is supported byseismic stratigraphy, attribute seismic and seismic inversion, show facies changein Toolachee resulting truncated sand body. This study produces a comprehensivefacies distribution both laterally and vertically. Therefor, next well should bedrilled along channel geometry]"

"Cekungan Browse merupakan salah satu cekungan besar yang tergabung dalam Westralian Superbasin. Cekungan Browse tersusun atas beberapa formasi dengan lingkungan pengendapan berbeda. Penelitian ini akan berfokus pada lingkungan fluvial yang terdapat pada Formasi Plover, Formasi Jamieson, Formasi Woolaston, dan Formasi Johnson pada Cekungan Browse. Metode yang digunakan adalah seismik geomorfologi, yaitu menganalisis fitur geomorfologi pada data seismik yang sebelumnya diolah melalui spektral dekomposisi, sehingga terbentuk gambaran lingkungan pengendapan pada tiap formasi. Dilakukan pencarian endapan channel dan perhitungan geometri channel untuk mengetahui arsitektur serta evolusi yang terjadi pada channel daerah penelitian. Hasil dari penelitian memperlihatkan adanya deformasi pada Formasi Plover sehingga fitur seismik sulit dikenali. Ditemukan beberapa endapan channel pada Formasi Jamieson, Formasi Johnson, dan Formasi Woolaston dengan tipe sungai braided. Arsitektur channel terlihat jelas pada lapisan Formasi Woolaston.

---

Browse Basin is one of the large basins that are part of the Westralian Superbasin. Browse Basin is composed of several formations with different depositional environments. This research will focus on the fluvial environment in the Plover Formation, Jamieson Formation, Woollaston Formation, and Johnson Formation in  Browse Basin. The method used is seismic geomorphology, which analyzes geomorphological features in seismic data, processed through spectral decomposition which show a picture of the depositional environment that formed in each formation. Channel deposits analysis and calculation of channel geometry was done to determine the architecture and evolution that occurred in the channel in the study area. The results this study show that there is deformation in the Plover Formation that seismic features are difficult to identify. Several channel deposits were found in the Jamieson Formation, the Johnson Formation, and the Woolaston Formation with braided river types. The channel architecture is clearly visible in the Woolaston Formation layers."

"Proses prediksi litologi sekaligus kandungan fluidanya merupakan bagian terpenting dalam karakterisasi reservoar. Salah satu metode yang digunakan dalam proses ini adalah metode inversi seismik simultan. Pada Lapangan Poseidon, Cekungan Browse, Australia, parameter-parameter yang dihasilkan melalui inversi seismik simultan kurang dapat mengkarakterisasi reservoar dengan baik karena saling tumpang tindihnya nilai impedansi antara hydrocarbon sand, water sand, dan shale yang menyebabkan tingkat ambiguitas yang tinggi dalam interpretasi. Inversi Poisson Impedance memberikan solusi terhadap permasalahan tersebut dengan cara merotasi impedansi beberapa derajat yang didapatkan melalui koefisien c. Hasilnya menunjukkan bahwa PI memberikan hasil yang lebih baik dalam memisahkan zona reservoar tersaturasi hidrokarbon. Berdasarkan hasil crossplot LI-GR, crossplot ¼- effecitive porosity, dan crossplot FI-Sw dengan nilai c masing-masing 2.04, 2.28, dan 1.05 didapatkan nilai korelasi optimum masing-masing 0.74, 0.91, dan 0.82 menunjukkan bahwa litologi porous sand tersaturasi hidrokarbon berada berada pada nilai LI ≤2800(m/s)(g*cc), 𝜙𝐼 ≤-5500(m/s)(g*cc), dan FI ≤3750(m/s)(g*cc). Keberadaan nilai LI, ϕI, dan FI yang rendah ini berkorelasi baik dengan keberadaan hidrokarbon pada sumur. Masing-masing nilai c tersebut kemudian diaplikasikan pada data seismik. Hasilnya menunjukkan bahwa distribusi persebaran porous sand tersaturasi Hidrokarbon pada penampang inversi seismik terlihat pada arah timur laut-barat daya yang diperkirakan sebagai arah persebaran gas.

---

The prediction process of lithology and fluid are the most important parts of reservoir characterization. One of the methods used in this process is the simultaneous seismic inversion method. In the Poseidon field, Browse Basin, Australia, the parameters generated through simultaneous seismic inversion are not able to characterize the reservoir accurately because of the overlapping impedance values between hydrocarbon sand and shale which causes a high level of ambiguity in the interpretation. The Poisson Impedance inversion provides a solution to this problem by rotating the impedance through the coefficient c. Based on the results of the LI-GR crossplot, the 𝜙I-effective porosity crossplot, and the FI-SW crossplot with c values of 2.04, 2.28, and 1.05 respectively, obtained the optimum correlations of 0.74, 0.91,and 0.82 respectively, indicating that hidrocarbon-saturated porous sand is at the value of LI ≤ 2800 (m/s)(g *cc), 𝜙I ≤ 5500 (m/s)(g*cc), and FI ≤ 4000 (m/s)(g*cc). The presence of low values of LI, 𝜙I, and FI correlates accurately with the presence of hydrocarbons in the well. The results show that the distribution of hydrocarbon saturated porous sand on the seismic inversion section is seen in the northeast-southwest direction which is estimated as the direction of gas distribution."

"Cekungan Sunda merupakan salah satu cekungan sedimen penghasil hidrokarbon terbesar di Indonesia. Reservoar utama berupa batupasir pada cekungan tersebut berada pada Formasi Talang Akar. Formasi ini terendapkan di daerah fluvio-deltaic atau fluvial sampai daerah transisi, sehingga karakter reservoar batupasir formasi ini cukup beragam. Untuk memaksimalkan hal ini dilakukan studi terkait lingkungan pengendapan dan zona potensi reservoar hidrokarbon melalui analisis log sumur, batuan inti, dan laporan biostratigrafi. Berdasarkan hasil analisis pola elektrofasies, daerah penelitian terdiri dari empat pola yaitu cylindrical, bell, symmetrical, dan serrated. Hasil asosiasi fasies daerah penelitian diinterpretasikan sebagai tidal sand bar, tidal point bar, intertidal flat, dan marsh/swamp yang berada pada lingkungan pengendapan tide-dominated estuary. Pada analisis petrofisika didapat nilai rata-rata parameter petrofisika kelima sumur yaitu Volume Shale (Vsh): 15.2% – 26.8%; Porositas Efektif (PHIE): 19.3% – 25.5%; Saturasi Air (Sw): 28% – 53.9%. Nilai ketebalan zona hidrokarbon (net pay) dihitung dengan parameter cut off yaitu Vsh ≤ 58%, porositas ≥ 8%, dan Sw ≤ 88%. Net pay atau total ketebalan zona hidrokarbon pada kelima sumur antara lain yaitu K-1 72.5 ft, K-2 182.5 ft, K-3 249.91 ft, K-4 59.3 ft, dan K-5 11.5 ft.

---

The Sunda Basin is one of the largest hydrocarbon-producing sedimentary basins in Indonesia. The main sandstone reservoir in the basin is the Talang Akar Formation. This formation was deposited in fluvio-deltaic or fluvial to transitional areas, so the character of the sandstone reservoir of this formation is quite diverse. To maximize this, a study was conducted related to the depositional environment and potential hydrocarbon reservoir zones through the analysis of well logs, cores, and biostratigraphic reports. Based on the results of the electrofacies pattern analysis, the research area consists of four patterns, namely cylindrical, bell, symmetrical, and serrated. The results of the facies association of the research area are interpreted as tidal sand bar, tidal point bar, intertidal flat, and marsh/swamp in a tide-dominated estuary depositional environment. In the petrophysical analysis, the average value of the petrophysical parameters of the five wells is obtained, namely Volume Shale (Vsh): 15.2% - 26.8%; Effective Porosity (PHIE): 19.3% - 25.5%; Water Saturation (Sw): 28% - 53.9%. The hydrocarbon zone thickness value (net pay) was calculated with cut off parameters of Vsh ≤58%, porosity ≥8%, and Sw ≤88%. Net pay or total hydrocarbon zone thickness in the five wells are K-1 72.5 ft, K-2 182.5 ft, K-3 249.91 ft, K-4 59.3 ft, and K-5 11.5 ft."

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

---

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

"[Lapangan “X” merupakan lapangan gas terbesar di delta mahakam dengan luas area permukaan yang mancapai 1350km2 dan total akumulasi gas terproduksi mencapai 8 tcf sejak tahun 1990 hingga saat ini. Penurunan produksi yang cukup tajam melatarbelakangipengembangan gas di zona dangkal (shallow gas). Sedimen pada zona dangkal ini tersusun oleh endapan deltaik berumur Miosen Atas – Pliosen dengan batupasir sebagai batuan reservoar utama. Keberadaan fluida gas pada batupasir akan berdampak pada penurunan kecepatan gelombangP dan densitas batuan sehingga memberikan kontras impendansi akustik yang kuat terhadaplapisan shale. Kontras impedansi akustik ini terlihat sebagai anomali amplitudo (brightspot)pada seismik. Adanya kenaikan nilai amplitudo seiring dengan bertambah besarnya sudutdatang menjadi hal yang menarik dalam interpretasi shallow gas ini.Tujuan dari penelitian ini adalah untuk mendeteksi keberadaan shallow gas di lapangan “X”menggunakan atribut AVO Sismofacies dengan 2 sumur yang dijadikan referensi untukpemodelan synthetic AVO. Penulis menggunakan 2 sumur lainnya sebagai kalibrasi terhadapanomali AVO dari Sismofacies cube yang dihasilkan.Metode AVO sismofacies ini tidak menggunakan parameter intercept (A) dan gradient (B)untuk kalkulasi AVO melainkan menggunakan dua data substack yaitu Near dan Far stack.Crossplot antara Near dan Far pada zona water bearing sand dan shale diambil untukmendapatkan background trend sehingga anomali yang berada diluar trend tersebut dapatdiinterpretasikan sebagai gas sand.Hasil dari analisis AVO Sismofacies ini cukup baik dan menunjukkan kesesuaian denganinterpretasi gas di beberapa sumur dan efek Coal berkurang jika dibandingkan Far stack.Meskipun demikian interpretasi AVO ini sebaiknya diintergrasikan dengan analisis dariatribut seismik lainnya untuk memperkuat interpretasi;Field “X” is a giant gas field in mahakam delta which cover 1350km2 of the area with totalcummulative gas production has reached 8 tcf since 1990 to recently. A significantdecreasing of gas production has led to produce gas accumulation in shallow zone as aneffort to fight againts this decline. Shallow zone is a deltaic sediments which depositedduring Upper Miocen to Pliocene with dominant reservoir is sandstone.The presence of gas in sandstone has an impact on decreasing of velocity P as well as densitywhich giving a contrast of acoustic impedance to the overlaying shale. Contrast ofimpedance can be observes in seismic as an amplitude anomaly or so called a brightspot. Anincrease of amplitude along the offset become more interesting in shallow gas interpretation.The aim of this study is to detect shallow gas accumulation di field “X” by using AVOSismofacies attribute with 2 wells as references to model respons of AVO. The result ofAVO sismofacies will be a cube and the interpreation will be calibrated with 2 existing wellscontaining proven gas bearing sands.AVO Sismofacies method will introduce Near and Far substack to be used in the calculationinstead of using common AVO paramter intecepth (A) and gradient (B). A crossplot betweensubstacks will create a background trend from water bearing zone and shale hence anyoutliers can, then,be interpreted as gas anomaly.AVO Sismofacies result is encouraging and some of AVO anomaly has been well calibratedwith existing wells. Coal effect which led to misintepretaion in shallow gas sand isdiminished compared to Far stack. Despite of this result, this anomaly interpretation need tobe intergrated with anothers seismic attribute to gain the level of confidence for shallow gasinterpretation., Field “X” is a giant gas field in mahakam delta which cover 1350km2 of the area with totalcummulative gas production has reached 8 tcf since 1990 to recently. A significantdecreasing of gas production has led to produce gas accumulation in shallow zone as aneffort to fight againts this decline. Shallow zone is a deltaic sediments which depositedduring Upper Miocen to Pliocene with dominant reservoir is sandstone.The presence of gas in sandstone has an impact on decreasing of velocity P as well as densitywhich giving a contrast of acoustic impedance to the overlaying shale. Contrast ofimpedance can be observes in seismic as an amplitude anomaly or so called a brightspot. Anincrease of amplitude along the offset become more interesting in shallow gas interpretation.The aim of this study is to detect shallow gas accumulation di field “X” by using AVOSismofacies attribute with 2 wells as references to model respons of AVO. The result ofAVO sismofacies will be a cube and the interpreation will be calibrated with 2 existing wellscontaining proven gas bearing sands.AVO Sismofacies method will introduce Near and Far substack to be used in the calculationinstead of using common AVO paramter intecepth (A) and gradient (B). A crossplot betweensubstacks will create a background trend from water bearing zone and shale hence anyoutliers can, then,be interpreted as gas anomaly.AVO Sismofacies result is encouraging and some of AVO anomaly has been well calibratedwith existing wells. Coal effect which led to misintepretaion in shallow gas sand isdiminished compared to Far stack. Despite of this result, this anomaly interpretation need tobe intergrated with anothers seismic attribute to gain the level of confidence for shallow gasinterpretation.]"

"Formasi Talang Akar yang saat ini merupakan reservoir utama penghasil hidrokarbon yaitu sebanyak 75% akumulasi hidrokarbon dari Cekungan Sumatra Selatan dihasilkan oleh Formasi Talang Akar. Untuk memaksimalkan serta menemukan zona reservoir baru yang dapat dijadikan zona potensi akumulasi hidrokarbon, maka penelitian ini dilakukan yaitu dengan menentukan atau mengidentifikasi zona potensi reservoir hidrokarbon pada Formasi Talang Akar. Penelitian ini dilakukan dengan menggunakan beberapa data yaitu data log, Routine Core Analysis (RCA), data XRD, data mudlog, dan data biostratigrafi dengan pengolahan data yang dilakukan yaitu secara kualitatif dan secara kuantitatif. Berdasarkan pengolahan data secara kualitatif dapat diamati litologi dari seluruh sumur yaitu berupa batupasir dengan selingan serpih dan terdapat beberapa endapan tipis batubara. Penentuan litologi ini dapat dilihat dari pembacaan log dan dengan validasi data mudlog. Berdasarkan analisis kuantitatif atau petrofisika, hasil perhitungan parameter petrofisika pada sumur penelitian didapatkan rata-rata pada zona hidrokarbon dengan Volume Shale (Vshale): 0,195 s.d. 0,298 V/V, Porositas Efektif (PHIE): 19% s.d. 34%, Saturasi Air (Sw): 0,371 s.d. 0,616 V/V. Nilai cut off yang digunakan untuk menentukan ketebalan zona hidrokarbon (net pay) yaitu Vshale ≤ 0.4 V/V, PHIE ≥ 12%, dan Sw ≤ 0.7 V/V. Ketebalan zona hidrokarbon dari masing-masing sumur yaitu X1: 18,5 ft, X2: 13 ft, X3: 4,7 ft, X4: 63 ft, dan X5: 1,7 ft.

---

The Talang Akar Formation is currently the main hydrocarbon-producing reservoir, 75% of the hydrocarbon accumulation of the South Sumatra Basin is produced by the Talang Akar Formation. To maximize and find new reservoir zones that can be used as potential hydrocarbon accumulation zones, this research was conducted by determining or identifying potential hydrocarbon reservoir zones in the Talang Akar Formation. This research was conducted using several data, namely log data, Routine Core Analysis (RCA), XRD data, mudlog data, and biostratigraphic data with data processing carried out qualitatively and quantitatively. Based on qualitative data processing, it can be observed that the lithology of all wells is sandstone with shale interludes and there are several thin deposits of coal. This lithology determination can be seen from log readings and by validating mudlog data. Based on quantitative or petrophysical analysis, the results of the calculation of petrophysical parameters in the research wells obtained an average in the hydrocarbon zone with Volume Shale (Vshale): 0.195 to 0.298 V/V, Effective Porosity (PHIE): 19% to 34%, Water Saturation (Sw): 0.371 to 0.616 V/V. The cut off values used to determine the thickness of the hydrocarbon zone (net pay) are Vshale ≤ 0.4 V/V, PHIE ≥ 12%, and Sw ≤ 0.7 V/V. The hydrocarbon zone thickness of each well is X1: 18.5 ft, X2: 13 ft, X3: 4.7 ft, X4: 63 ft, and X5: 1.7 ft."

"Lapangan SF adalah salah satu lapangan yang berada di Sub-Cekungan Jambi. Lapangan ini terbukti menghasilkan minyak dan gas di dalam reservoar batupasir Formasi Air Benakat dan Formasi Gumai. Lapangan ini ditinggalkan selama 20 tahun dikarenakan tekanan reservoar yang rendah, jumlah gas yang tinggi, masalah distribusi fluida resevoar serta masalah mekanikal lainnya. Hal inilah yang menjadi faktor bahwa lapangan ini perlu langkah interpretasi bawah permukaan lebih lanjut untuk mendapatkan reservoar baru yang prospektif dan dapat mengoptimalisasi produksi. Studi ini dilakukan pemodelan penyebaran fasies, parameter petrofisika dan perhitungan cadangan hidrokarbon untuk mengetahui arah perkembangan reservoar yang baik pada lapangan ini. Dari hasil penelitian menunjukkan adanya endapan sedimen sand tidal bar yang memiliki karakter reservoar yang baik dengan porositas rata-rata sebesar 21-24 %. Endapan sand tidal bar terakumulasi di bagian barat daya lapangan. Selain itu, dari hasil perhitungan cadangan diprediksi lapangan ini masih menyimpan 18 MMSTB minyak dan 2 BCF gas.

---

SF field is located in Jambi Sub-Basin. This field proven to produce oil and gas in sand reservoir of Air Benakat Formation and Gumai Formation. Twenty years this field was suspended due to low reservoir pressure, high gas oil ratio, reservoir fluid distribution and mechanical problems. Therefore, this field needs more interpretation to get new reservoir and can optimalization the production. This study will focus only in P Interval, Gumai Formation that indicates potential for further drilling to develop.

The aim of this study is to delineate fasies and petrophysics distribution, and also to calculate reserves for indicating good reservoir direction in this field. The result of this study indicates there is sediment of sand tidal bar and this facies accumulates in the south-west of SF field. Sand tidal bar has a porosity value from 21%-24%. In addition, from the volume calculation of hydrocarbon this field is predicted still have 18 MMSTB of oil and 2 BCF of gas."

"Lapangan “SJ” merupakan salah satu lapangan produksi migas yang terletak di Cekungan Sumatera Tengah yang saat ini dikelola oleh PT. Pertamina Hulu Rokan. Lapangan ini mulai diproduksi sejak tahun 1975 dengan jumlah total pengeboran hingga saat ini sebanyak 57 sumur. Pada lapangan ini terdapat potensi reservoir gas di Formasi Petani dan belum dilakukan perhitungan cadangannya. Penelitian ini bertujuan untuk melakukan perhitungan nilai cadangan gas (OGIP) pada Lapangan “SJ”, Formasi Petani, Cekungan Sumatera Tengah dengan menggunakan metode perhitungan 2D volumetric. Hasil penelitian menunjukkan bahwa potensi reservoir pada Formasi Petani dibagi menjadi 3 unit yaitu U PTUA, PTUA, dan PTA. Ketiga reservoir memiliki rentang nilai porositas efektif sebesar 19-25% dan saturasi air sebesar 62-72%. Hasil perhitungan cadangan gas (OGIP) dengan metode 2D volumetric pada Formasi Petani adalah sebesar 378 MMSCF untuk U PTUA, 251 MMSCF untuk PTUA, dan 401 MMSCF untuk PTA.

---

The "SJ" Field is one of the oil and gas production fields located in the Central Sumatra Basin, currently managed by PT. Pertamina Hulu Rokan. The field has started production in 1975 with a total of 57 drilled wells. Within the field, there are potential gas reservoirs in the Petani Formation that have not yet been evaluated for the reserve values. The research aims to calculate the gas reserve value (OGIP) in the "SJ" Field, Petani Formation, Central Sumatra Basin using a 2D volumetric method. The research findings indicate that the reservoir potential within the Petani Formation is divided into three units: U PTUA, PTUA, and PTA. All three reservoirs have an effective porosity ranging from 19% to 25% and water saturation ranging from 62% to 72%. The gas reserve calculation (OGIP) using the 2D volumetric method for the Petani Formation is estimated to be 378 MMSCF for U PTUA, 251 MMSCF for PTUA, and 401 MMSCF for PTA."

"Lapangan G yang berlokasi pada Cekungan Sumatera Selatan, merupakan salah satu lapangan reservoar hidrokarbon. Untuk mengetahui karakter dari reservoar Lapangan G, dalam penelitian ini, dilakukan pendekatan petrofisika serta penggunaan multi atribut seismik dengan metode Probabilistic Neural Network yang berfokus pada Formasi Gumai. Atribut seismik yang digunakan adalah atribut sesaat, yaitu amplitudo sesaat, fase sesaat, dan frekuensi sesaat serta parameter nilai petrofisika yang dicari adalah nilai porositas, saturasi air, dan volume shale. Anomali seismik Lapangan berupa dim spot diantara kedua patahan utama yang berorientasi NorthWest-SouthEast dan patahan berorientasi NorthEast-SouthWest, diperkirakan sebagai tempat akumulasi hidrokarbon. Output utama penelitian ini adalah hasil lumping untuk melihat zona suatu sumur yang memiliki prospek hidrokarbon dan hasil volume seismik prediksi dari ketiga nilai parameter petrofisika serta output sampingan dari interpretasi penampang seismik. Baik hasil lumping dan volume seismik prediksi, menampilkan bahwa Formasi Gumai memiliki prospek hidrokarbon yang juga ditampilkan pada data sumur, didapatkan bahwa Zona 5 pada Sumur G1 dan Zona 4 pada Sumur G3 memiliki prospek cadangan hidrokarbon dengan nilai volume shale sebesari 0.500, nilaii saturasii airi sebesari 0.406, dan nilai porositas sebesar 0.131.

---

Field G, which is located in the South Sumatera Basin, isi onei ofi thei hydrocarboni reservoir fields. To determine thei character ofi thei G Field reservoir, in this study, a petrophysical approach was used and the use of multiple seismic attributes using the Probabilistic Neural Network method which focused on the Gumai Formation. Seismic attributes used are instantaneous attributes, namely instantaneous amplitude, instantaneous phase, and instantaneous frequency and the parameters of the petrophysical value sought are the value of porosity, water saturation, and shale volume. Seismic anomaly in the field in the form of a dim spot between the two main faults oriented NorthWest-SouthEast and fault oriented NorthEast- SouthWest, is estimated as a place of accumulation of hydrocarbons. The main output of this research is the lumping results to see the zone of a well that has hydrocarbon prospects and the predicted seismic volume results from the three petrophysical parameter values as well as the side output from the interpretation of the seismic cross-section. Both the lumping results and the predicted seismic volume, showing that the Gumai Formation has a hydrocarbon prospect which is also shown in the well data, it is found that Zone 5 in Well G1 and Zone 4 in Well G3 have prospects for hydrocarbon reserves with a shale volume value of 0.500, a water saturation value of 0.406, and a porosity value of 0.131."