Analisis Biomarka Hidrokarbon Alifatik pada Batu Bara JT-01 Formasi Ngrayong, Jatirogo, Tuban, Jawa Timur

Shalsabila, Hafizhah (2025) Analisis Biomarka Hidrokarbon Alifatik pada Batu Bara JT-01 Formasi Ngrayong, Jatirogo, Tuban, Jawa Timur. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Karakterisasi geokimia organik pada sampel batu bara JT–01 dari Formasi Ngrayong, Jatirogo, Tuban, Jawa Timur telah berhasil dilakukan melalui analisis biomarka fraksi hidrokarbon alifatik dengan menggunakan metode ekstraksi, fraksinasi, dan identifikasi biomarka, khususnya Kromatografi Gas-Spektrometri Massa (KG–SM). Analisis ini bertujuan untuk mengetahui sumber bahan organik, lingkungan pengendapan, dan tingkat kematangan termal batu bara JT–01 guna menentukan potensinya sebagai penghasil gas (gas-prone) atau minyak (oil-prone). Hasil identifikasi menunjukkan bahwa kelimpahan senyawa n-alkana yang signifikan mengindikasikan bahan organik berasal dari berbagai sumber. Beberapa parameter, seperti CPI (3,82), OEP-2 > OEP-1 (2,94 > 1,06), TAR (59,08), Paq (0,12), LHCPI (0,03), ACL (29,71), LMW/HMW (0,02), AlkTerr (0,68), dan wax index (0,05), serta keberadaan senyawa seskuiterpenoid bisiklik dan triterpenoid pentasiklik menunjukkan dominasi input bahan organik dari tanaman tingkat tinggi terestrial dan bakteri, lingkungan pengendapan oksidatif, dan kematangan termal rendah pada batu bara muda. Hasil analisis menunjukkan deret homolog n-alkana (n-C17 – n-C35) dengan kelimpahan tertinggi pada n-C31 mengindikasikan dominasi input bahan organik berasal dari tumbuhan tingkat tinggi terestrial dibandingkan dengan bakteri pada sampel JT–01. Nilai rasio Pr/Ph > 1 menunjukkan bahwa bahan organik batu bara berada dalam lingkungan pengendapan oksidatif. Identifikasi senyawa neohop-13(18)-ena, hop-17(21)-ena, 17β(H),21β(H)-30-norhopana, dan 17β(H),21β(H)-homohopana menunjukkan tingkat kematangan termal rendah dan biodegradasi yang tinggi. Plot parameter Pr/n-C17 dan Ph/n-C18 pada diagram Hunt menunjukkan bahwa batu bara JT–01 tergolong batu bara humat dengan kerogen transisi Tipe II menuju III. Kerogen Tipe III mengindikasikan adanya potensi batuan sumber untuk bertransisi ke zona gas basah (wet gas) dan kering (dry gas). Oleh karena itu, sampel batu bara JT–01 dari Formasi Ngrayong, Jatirogo, Tuban, Jawa Timur ini berpotensi signifikan menghasilkan gas (gas-prone).
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The organic geochemical characterisation of the JT–01 coal from the Ngrayong Formation, Jatirogo, Tuban, East Java, has been successfully conducted through analysis of biomarker aliphatic hydrocarbon fractions using extraction, fractionation, and biomarker identification methods, particularly Gas Chromatography-Mass Spectrometry (GC–MS). This analysis aims to determine the source of organic matter, depositional environment, and thermal maturity level of the JT–01 coal to assess its potential as a gas-prone or oil-prone resource. The results showed a significant abundance of n-alkane compounds, indicating that the organic material originated from multiple sources. Several parameters were assessed, such as the Carbon Preference Index (CPI) determined to be 3,82, and the OEP-2 value exceeded OEP-1 (2,94 > 1,06), with TAR at 59,08, Paq at 0,12, LHCPI at 0,03, ACL at 29,71, LMW/HMW at 0,02, AlkTerr at 0,68, and a wax index of 0,05. Furthermore, the presence of bicyclic sesquiterpenoids and pentacyclic triterpenoids indicated that the input of organic matter was predominantly from high-level terrestrial plants and bacteria, which is consistent with an oxidative depositional environment and young coal conditions characterised by low thermal maturity. The analysis revealed a homologous series of n-alkanes ranging from n-C17 to n-C35, with the highest abundance detected in n-C31. This analysis suggests a predominance of high-level terrestrial plant input compared to bacterial input in the JT–01 samples. A Pr/Ph ratio greater than 1 indicates that the organic matter is buried in an oxic environment. The identification of compounds such as neohop-13(18)-ene, hop-17(21)-ene, 17β(H),21β(H)-30-norhopane, and 17β(H),21β(H)-homohopane points to low thermal maturity accompanied by a high biodegradation rate. When plotted on the Hunt diagram, the Pr/n-C17 and Ph/n-C18 classify the JT–01 coal sample as a humic, with a kerogen type transitioning from Type II to III. Type III kerogen suggests the potential for source rocks to transition from wet and dry gas zones. In conclusion, the Coal of JT–01 from the Ngrayong Formation in Jatirogo, Tuban, East Java, exhibits great potential for gas production (gas-prone).

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Biomarka, Formasi Ngrayong, Geokimia Organik, Hidrokarbon Alifatik, KG–SM, Aliphatic Hydrocarbon, Biomarkers, GC–MS, Ngrayong Formation, Organic Geochemistry
Subjects:	Q Science > QD Chemistry > QD251.2 Chemistry, Organic. Biochemistry
Divisions:	Faculty of Science and Data Analytics (SCIENTICS) > Chemistry > 47201-(S1) Undergraduate Thesis
Depositing User:	Hafizhah Shalsabila
Date Deposited:	09 Jul 2025 07:52
Last Modified:	09 Jul 2025 07:52
URI:	http://repository.its.ac.id/id/eprint/119434

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