Distribution of naphthalenes in crude oils from the Java Sea: Source and maturation effects
- Insitute of Petroleum and Organic Geochemistry, Juelich (Germany)
- Carl von Ossietzky Univ., Oldenburg (Germany)
- Institute of Earth Sciences, Utrecht (Netherlands)
Amounts and distributions of C[sub 1]-C[sub 3] naphthalenes and cadalene were determined by capillary gas chromatography in sixty crude oil samples from the Java Sea, southeast Asia and in a sample of Talang Akar (Oligocene) resinite supposed to be a major contributor of hydrocarbons to oils in that area. Maturity of the oils was assessed by the Methylphenanthrene Index (MPI-1). Source effects discovered by scatterplots were scrutinized by Principal Component Analysis (PCA). Based on empirical relationships with C[sub 27]-C[sub 29] steranes (measured by gas chromatography-mass spectrometry), dimethylnaphthalenes in oils from the Ardjuna and Jatibarang (sub-)basins are mainly derived from terrestrial sources. Transition to a marine depositional environment in the Sunda basin, as indicated by a decrease in C[sub 29] sterane relative abundance from 70 to 30%, results in a decrease of total dimethylnaphthalene (DMN) concentrations from 20 to less than 3 mg/g oil. This is due, mainly, to a decrease in the concentration of the dominant 1,6-DMN. Thus, terrestrial Ardjuna or Jatibarang oils rich in 1,6-DMN (2-15 mg/g oil) are readily discriminated from marine Sunda oils (0.2-2 mg 1,6-DMN/g oil). Resinite of the Talang Akar type (1.4 mg 1,6-DMN/g total organic matter [TOM]) appears to be a significant contributor of 1,6-DMN to oils in the Ardjuna basin. Terrestrial affinities are inferred also for cadalene from concentration levels that are higher in terrestrial oils (1-3 mg/g oil) and Talang Akar resinite (6 mg/g TOM) than in the marine oils (0.1-1 mg/g oil). Ardjuna basin oils have the highest concentrations of cadalene, hence supporting resinite of the Talang Akar type as a possible source. However, 1,6-DMN and cadalene are likely to be derived from different terrestrial organic matter sources, because they load on different factors in PCA.
- OSTI ID:
- 6471151
- Journal Information:
- Geochimica et Cosmochimica Acta; (United States), Vol. 58:17; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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