Minyak bumi dari sumur minyak tradisional di daerah Babat, Kabupaten Musi Banyuasin, Sumatera Selatan merupakan hasil penambangan minyak secara manual dengan kedalaman reservoir dangkal antara 60-150 meter. Antiklin tertutup berperan sebagai perangkap minyak bumi, sementara batuan sumber penghasil hidrokarbon yang menyuplai minyak bumi ke dalam reservoir tidak diketahui secara pasti karena tidak adanya data log maupun geokimia. Hasil analisis 6 buah sampel minyak bumi dengan metode GC-MS menunjukkan bahwa komposisi minyak bumi terdiri atas 64.8-90.7% alifatik, 3.9-21.6% aromatik, 0-6.9% alkohol dan 1.1-10.8% keton/esther. Rasio Pr/C17 (0.89) dan Ph/C18 (0.29-0.31) menunjukkan asal material organik berasal dari tanaman asal darat yang sedikit bercampur dengan alga. Rasio Pr/Ph antara 3.3-3.4 dan Pr/C17 0.89 menunjukkan bahwa batuan sumber diendapkan pada lingkungan anoxic to suboxic lacustrine or marine. Batuan induk potensial yang berkembang di Cekungan Sumatera Selatan diantaranya berasal dari Formasi Lemat/Lahat, Formasi Talang Akar, dan Formasi Gumai. Berdasarkan hasil analisis, dapat disimpulkan bahwa minyak bumi dari daerah Babat berkorelasi dengan Formasi Lemat/Lahat sebagai batuan induk penghasil hidrokarbon karena formasi tersebut diendapkan pada lingkungan lacustrine.

Crude oils from a conventional well in Babat, Musi Banyuasin Regency, South Sumatra have been manually brought to the surface from a shallow reservoir (60 to 150 meters depth). A closed anticline acts as the hydrocarbon trap while the source rock supplying hydrocarbons to the reservoir is uncertain, due to the absence of well log and geochemical data. The results of 6 samples analysed with GC-MS show that the crude oil composition consists of 64.8-90.7% aliphatics, 3.9-21.6% aromatics, 0-6.9% alcohol and 1.1-10.8% ketone/esther. The ratio of Pr/C17 (0.89) and Ph/C18 (0.29-0.31) shows that the oils were derived from terrestrial higher plants and partially mixed with algae. The Pr/Ph ratio between 3.3-3.4 and the Pr/C17 ratio of 0.89 indicates that the unknown source rock may have been deposited in an anoxic to suboxic lacustrine or marine environment. The potential source rocks that could have yielded these hydrocarbons in the South Sumatra Basin are possibly the Lemat/Lahat Formation, the TalangAkar Formation or the Gumai Formation. Based on the analytical results, it is hypothesized that the crude oil from the Babat Area may best fit having the Lemat/Lahat Formation as the source because that formation was deposited in a lacustrine environment.

Kata Kunci : isoprenoid, organik, pristan, phytan, minyak bumi