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MEKANISME OVERPRESSURE PADA SUMUR SM-1, CEKUNGAN SUMATRA UTARA Anak Agung Sagung Mayun Yudhyasmara Prabandari; Muhammad Burhannudinnur; Junita Trivianty Musu; Ricky Andrian Tampubolon
Journal of Geoscience Engineering & Energy (JOGEE) VOLUME 2, NOMOR 1, FEBRUARI 2021
Publisher : Universitas trisakti

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1398.904 KB) | DOI: 10.25105/jogee.v2i1.8931

Abstract

Cekungan Sumatra Utara merupakan salah satu cekungan produktif di Indonesia yang diketahui memiliki kondisi overpressure berdasarkan beberapa peneliti terdahulu, seperti Aziz dan Bolt (1984) dan Hutasoit, dkk. (2013). Penelitian dilakukan untuk mengetahui zona overpressure pada sumur pengeboran SM-1 di Lapangan “AAS” dengan berdasarkan perhitungan besarnya nilai tekanan pori, mengetahui kedalaman top overpressure, dan mengetahui mekanisme penyebab overpressure berdasarkan log sonic, log densitas, dan log neutron. Nilai tekanan pori didapatkan berdasarkan perhitungan dengan metode Eaton menggunakan data log sonic. Diketahui top overpressure Sumur SM-1 pada kedalaman 1653 ft, dimana zona overpressure berada pada kedalaman 1653 – 2510 ft, 3195 – 3473 ft, dan 4205 – 4486 ft (Formasi Baong). Mekanisme penyebab overpressure pada Sumur SM-1 adalah mekanisme loading berupa disequilibrium compaction.
APPLICATION OF OLEANANE AND STERANE INDEX FOR BIOSTRATIGRAPHIC AGE DETERMINATION: EXAMPLES FROM KANGEAN OILS, NORTHEAST JAVA BASIN Himawan Sutanto; Junita Trivianty Musu
Scientific Contributions Oil and Gas Vol. 37 No. 1 (2014): SCOG
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/scog.37.1.207

Abstract

Northeast Java Basin is known as mature Cenozoic basin, yet this understanding override possibility ofsediment older than Cenozoic. This thoughthas brought current exploration strategy of this basin concerningwithin only Cenozoic sediments. Therefore, it is believed that the source rock in this basin was also derivedfrom Cenozoic sediments, especially the Ngimbang Formation, which was formed during Late Eoceneto Early Oligocene in the stage of Early Synrift. On the other hand, the occurrence of Alisporites sp haspointed Cretaceous sediments is a potential source rock. However, it is still debatable due to the presence ofAlisporites similis in Serawak Basin of Malaysia, which is present until Paleocene. Three crude oils from theKangean oil fi eldNortheast Java Basin, namely NEJB-748, NEJB-749 and NEJB-750have been investigatedusing gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS).Kangean oils areclassifi ed as mixed oil with organic matter originated from marine and terrestrial deposited under oxidizingand reducing conditions. Moreover, Kangean oils show very low oleanane and steraneindexthat may leadus to the conclusion that the oils were originated from Cretaceous source rock.
DETERMINATION OF SHALE GAS POTENTIAL OF NORTH SUMATRA BASIN: AN INTEGRATION OF GEOLOGY, GEOCHEMISTRY, PETROPHYSICS AND GEOPHYSICS ANALYSIS Junita Trivianty Musu; Bambang Widarsono; Andi Ruswandi; Himawan Sutanto; Humbang Purba
Scientific Contributions Oil and Gas Vol. 38 No. 3 (2015): SCOG
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/scog.38.3.245

Abstract

A detailed combined geological and geophysical study in North Sumatra basin has shown thatprospective formations for shale play containing gas sweet spots are found to be in shales from Bampo,Belumai, and Baong Formations. Bampo Formation exhibits low shale gas potential with very low tomedium in organic material contents, maturity index of immature to mature, and moderate brittleness. Rockswithin the formation tend to be reactive to highly reactive to water, with a moderate degree of swellingcapacity. Porosity varies within 5.8 - 7.4 % with permeability ranging from 0.37 to 3.2 mD. Sweet spots inthe formation found around Basilam-1 and Securai-1wells occupy about 21% of the formation. On the otherhand, Belumai Formation shows moderate to good shale gas potential, with low to high organic materialcontents, immature to mature levels of maturity, and moderately brittle to brittle. Sweet spot areas in theformation found around the two wells are about 29% of the formation. For Baong Formation, analysisreveals moderate to good shale gas potential, with low to medium contents of organic material, immatureto mature in maturity index, moderately brittle to brittle in brittleness, and tendency of being reactiveto highly reactive to water but with low degree of swelling capacity. Sweet spots in the formation foundaround the two wells occupies are roughly 11% of the total formation volume in the area. Basin modelingleading to gas resources estimation for Baong, Belumai and Bampo Formations has led to estimatedvolumes of 6,379 TCF, 16,994 TCF, and 25,024 TCF, respectively, with a total amount of 48,397 TCF.The resources figures are speculative in nature and do not incorporate any certainty and efficiency factors.
NMR T, CUT OFF: WHICH ONE IS TO BE USED FOR APPLICATION? Bambang Widarsono; Junita Trivianty Musu
Scientific Contributions Oil and Gas Vol. 30 No. 3 (2007): SCOG
Publisher : Testing Center for Oil and Gas LEMIGAS

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Abstract

Recent developments in petroleum industry have been -witnessing the surge of the use of nuclearmagnetic resonance (NMR) log. Despite some remaining problems the NMR technology appearsto gain more acceptance as petrophysical tool for evaluating reservoir quality. Comprehensiveformation evaluation requires determination of irreducible fluids, movable fluids, and permeabil-ity. Hoyvever, rock heterogeneity introduces complexity in any formation evaluation activities.This can also cause problem for NMR log interpretation. In the presence of clays the most com-monly used T, cut off values, a constant value throughout a formation, seem to eventually yieldinaccurate irreducible yvater saturation estimates, as yvell as other output such as permeability.This study focuses at finding a solution for finding the best way of choosing the most representa-tive T, cut off value to be used in NMR log interpretation. This is indeed a common pressingproblem for heterogeneous formation rocks such as in the case of Tirrawarra sandstones used inthis study. The main part of the study is devoted to comparison between the use of single aver-aged T,c value and establishment of empirical correlations enabling the provision of T,c for anylevel of heterogeneity (i.e. various levels of shaliness). The study hoyvever surprisingly shoyvsthat, in spite of the theoretical soundness of the empirical correlations established, simple aver-aging of T,c values yielded by a reliable method proves itself adequate. This conclusion thereforehelps considerably in reducing complexity in NMR log interpretation. Key yvords: T,e irreducible yvater saturation, ductile components, empirical correlation, aver-aged T2c
TO EXPLAIN THE NATURE OF CORE POROSITY USING RESULTS OF PETROGRAPHY ANALYSIS Junita Trivianty Musu
Scientific Contributions Oil and Gas Vol. 30 No. 3 (2007): SCOG
Publisher : Testing Center for Oil and Gas LEMIGAS

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Abstract

The Permian to Triassic Tirrawarra Sandstone succession in the Cooper Basin of Cen-tral Australia is characterized by its low permeability. Ambient core porosity averages8.96% and ambient permeability 0.9 rnD. Most samples studied have permeabilities lessthan 3mD. Despite its overall poor resen’oir characteristics, the Tirrawarra Sandstone isone of the rnajor oil and gas targets in Australia. A total of 17 core plugs from 6 wellswere studied petrographically using optical petrography, SEM and XRD. These resultswere integrated with core analysis data. Petrographic study revealed the diagenetic events, rnainly mechanical and Chemicalcompaction, cementation and alteration have modified the reservoir quality. Ductile com-ponents such as rock fragments, clay and matrix influence mechanical compaction, whichare the main cause of resen’oir quality reduction. Quartz cementation and clay distribu-tion also affected the porosity, but particularly permeability. Mechanical compaction aswell as quartz cementation have reduced and blocked pore-throats to isolate intergranu-lar pores. The alteration of feldspar to kaolin has changed intergranular porosity tomicroporosity. Illite occurs as either cement, alteration of rock fragments or kaolinite. Aliof these diagenetic events also affect fluid movement in the resen’oir This paper presents the evaluation of the determination of effectiveness of porosity inthe delivery of gas from sandstone resen’oir in the Cooper Basin using integrated petrog-raphy analysis and core measurements. Key words: core porosity, core permeability, petrography analysis, diagenesis.
Analisis Lingkungan Pengendapan Formasi Batugamping Dayang Distrik Batanta Utara, Kabupaten Raja Ampat, Provinsi Papua Barat Fajar Kurniawan Rohmala; David V. Mamengko; Wiratama Rana; Pribowo A. Kusumo; Junita Trivianty Musu
Lembaran Publikasi Minyak dan Gas Bumi Vol. 54 No. 3 (2020): LPMGB
Publisher : BBPMGB LEMIGAS

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Abstract

Secara geologi, Daerah Yensawai didominasi oleh batuan beku sebagai basement (batuan dasar) dan batuan sedimen (batugamping dan silisiklastik) di mana daerah tersebut menjadi bagian dari Auwewa Volcanic Group. Batugamping Dayang merupakan salah satu formasi yang memiliki karakteristik relatif sama dengan batugamping di kawasan Auwewa Volcanic Group dan memiliki kesamaan dengan Batugamping Maruni dan Batugamping Kais. Penelitian ini menggunakan beberapa pendekatan analisis diantaranya adalah analisis geokimia (X-Ray Fluorescene/XRF), analisis provenance dan analisis microfasies karbonat. Analisis tersebut dimaksud untuk menentukan menetukan jenis litologi, lingkungan pengendapan, komposisi kimia batuan, dan asal material pembentuk batuan. Hasil analisis geokimia menunjukkan bahwa Batugamping Dayang terendapkan pada kondisi laju penguapan air laut (evaporasi) dan paleo salinitas yang rendah, laju reduksi sulfat yang cepat dan memiliki aliran yang tenang serta berenergi rendah. Hasil analisis provenance menunjukkan bahwa sumber Batugamping Dayang berasal dari area dissected arc dan transisional arc. Analisis mikrofasies karbonat daerah penelitian menujukkan daerah penelitian merupakan penciri dari deep shelf. Hasil penelitian ini menunjukan bahwa batugamping Dayang diendapkan pada lingkungan yang berbeda dengan batugamping Kais maupun batugamping Maruni. Hubungan stratigrafi batugamping Dayang kemiripan dengan batugamping Sagewin pada Formasi Gunungapi Dore diendapkan pada lingkungan fore reef environment sebagai island arc.