ASPAL BUTON: ANALISIS DAN KAJIAN GEOKIMIA HIDROKARBON

  • S.M. Tobing S.M. Tobing Pusat Sumber Daya Geologi

Abstract

Dua (2) conto aspal dari Formasi Sampolakosa, satu (1) conto batu serpih dari Formasi Winto, dan satu (1) conto  minyak rembesan  (oil seeps) dari Formasi Tondo dianalisis untuk studi hidrokarbon. Semua conto berasal dari P. Buton,Sulewesi Tenggara.

Hasil  kajian memberikan gambaran mengenai potensi hidrokarbon,kematangan termal,  kualitas bahan organik dan karakter lingkungan pengendapan darimana hidrokarbon bersumber.

Hasil   analisis    laboratorium  menunjukkan bahwa secara umum bahwa batu serpih Formasi Winto berpotensi sangat bagus   sebagai  batuan sumber hidrokarbon. Kandungan hidrogen di dalam bahan organik cukup tinggi yang mencerminkan kualitasnya sebagai kerogen Tipe II yang berasal dari organisme akuatik atau algal. Pada kondisi sekarang batu serpih lebih menunjukkan karakternya sebagai batu serpih minyak atau 'oil  shale'.  Diperlukan kematangan termal yang lebihtinggi dari kondisi sekarang untuk menguraikan kerogen Tipe II menjadi minyak dalam jumlah yang optimal.

KaJian   data   biomarker jelas menunjukkan tingkat kematangan termal relatif masih rendah pada batu serpih Fm. Winto. Minyak  rembesan  maupun aspal dihasilkan oleh batuan sumber dengan tingkat kematangan termal tinggi dan mengalamidegradasi  baik termal maupun biologis. Algal akuatik merupakan sumber bahan organik baik untuk rembesan minyak dan  aspal  maupun batu serpih Fm.  Winto.  Rembesan minyak diperkirakan  berasal dari batuan sumber yang diendapkan dalam lingkungan danau, sedangkan aspal berasal dari lingkungan marin karbonat. Batu serpih Fm.  Winto diperkirakan berasal  dari lingkungan pengendapan laut dangkal.

Tidak   dijumpai korelasi positif antara minyak rembesan,  aspal dan batu serpih Fm. Winto. Aspal berasal dari batuansumber  dengan lingkungan pengendapan marin karbonat.

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Published
2008-08-05
Section
Buletin Sumber Daya Geologi