Karakteristik Geokimia Organik Minyak Kondensat Alba, Cekungan Rio Muni, Equatorial Guinea

Samual, Theala Devia Aristya Amanda (2025) Karakteristik Geokimia Organik Minyak Kondensat Alba, Cekungan Rio Muni, Equatorial Guinea. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Sampel minyak kondensat dari Lapangan Alba di Cekungan Rio Muni, Equatorial Guinea, yang diperoleh melalui PT. Trans-Pacific Petrochemical Indotama (TPPI) di Tuban, Jawa Timur, telah dianalisis untuk tujuan karakterisasi geokimia organik. Penelitian geokimia organik terhadap sampel minyak kondensat ini, telah dilakukan untuk mengkaji sumber bahan organik, lingkungan pengendapan purba, dan tingkat kematangan termal melalui analisis biomarka. Sampel dianalisis menggunakan metode fraksinasi dan gabungan Kromatografi Gas–Spektrometri Massa (KG-SM). Identifikasi fraksi hidrokarbon alifatik menunjukkan distribusi n-alkana (n-C11 hingga n-C24) dengan kelimpahan dominan pada rantai pendek n-C12, serta nilai rasio ∑C21⁻/∑C22⁺ sebesar 5,84. Hal ini mengindikasikan kontribusi utama dari bahan organik laut, seperti alga dan bakteri laut. Parameter lain seperti CPI = 0,74 dan OEP = 0,94 juga menunjukkan indikasi sumber bahan organik marin. Rasio Pr/n-C17 = 0,83 dan Ph/n-C18 = 0,60, serta rasio Pr/Ph sebesar 2,59 mengindikasikan lingkungan pengendapan purba yang bersifat sub-oksik pada tahap diagenesis. Selain itu, pola distribusi isomer metildibenzofuran (MDBF) memperkuat interpretasi bahwa kondensat berasal dari lingkungan pengendapan laut. Fraksi hidrokarbon aromatik menunjukkan keberadaan senyawa-senyawa stabil secara termal seperti isokadalena, 2-MN, 2,6-DMN, dan 1,3,6-TMN. Nilai rasio MNR = 1,83, DMR = 0,995, dan TMR = 0,112 menunjukkan dominasi senyawa β-substituen, yang menjadi penanda kematangan lanjut. Indeks metilfenantrena (MPI-1) sebesar 0,68 dan MPI-3 sebesar 1,31 mengindikasikan bahwa sampel berada pada puncak jendela minyak atau awal transisi menuju zona gas. Hasil analisis biomarka ini secara keseluruhan menunjukkan bahwa minyak kondensat Alba terbentuk dari bahan organik marin yang diendapkan dalam lingkungan sub-oksik dan telah mengalami kematangan termal yang tinggi.
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Condensate oil samples from the Alba Field in the Rio Muni Basin, Equatorial Guinea, obtained through PT. Trans-Pacific Petrochemical Indotama (TPPI) in Tuban, East Java, were analyzed to characterize their organic geochemical properties. This study presents an organic geochemical investigation conducted to evaluate the origin of organic matter, depositional environment, and thermal maturity based on biomarker analysis. The samples were analyzed using fractionation techniques and Gas Chromatography-Mass Spectrometry (GC-MS). The aliphatic hydrocarbon fraction revealed the distribution of n-alkanes ranging from n-C11 to n-C24 with dominant abundances at short-chain n-C12. The ∑C21⁻/∑C22⁺ ratio = 5,84 indicates a primary contribution from marine organic matter such as algae and marine bacteria. Other parameters including CPI = 0.74 and OEP = 0,94 also suggest a marine origin. The ratios of Pr/n-C17 = 0,83 and Ph/n-C18 = 0,60, along with Pr/Ph = 2,59, indicate a suboxic depositional environment during early diagenesis. The distribution pattern of methyl dibenzofuran (MDBF) isomers further supports a marine setting. The aromatic hydrocarbon fraction showed the presence of thermally stable compounds such as isocadalene, 2-MN, 2,6-DMN, and 1,3,6-TMN. The values of MNR = 1,83, DMR = 0,995, and TMR = 0,112 reflect the dominance of β-substituted aromatic compounds, indicating high thermal maturity. Methylphenanthrene indices MPI-1 = 0,68 and MPI-3 = 1,31 suggest that the sample lies at the peak of the oil window or is transitioning into the early gas generation zone. These biomarker characteristics indicate that the Alba condensate originated from marine organic matter deposited under suboxic conditions and has reached an advanced stage of thermal maturity.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Alba condensate, Rio Muni Basin, organic geochemistry, biomarkers, GC–MS; Kondensat Alba, Cekungan Rio Muni, geokimia organik, biomarka, KG-SM
Subjects:	Q Science Q Science > QD Chemistry Q Science > QD Chemistry > QD251.2 Chemistry, Organic. Biochemistry
Divisions:	Faculty of Science and Data Analytics (SCIENTICS) > Chemistry > 47201-(S1) Undergraduate Thesis
Depositing User:	Theala Devia Aristya Amanda Samual
Date Deposited:	07 Aug 2025 01:11
Last Modified:	07 Aug 2025 01:11
URI:	http://repository.its.ac.id/id/eprint/127858

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