Biomarker Molecular Indicators Predict Biodegraded Heavy Oil Physical Properties: A Case from Dongying Depression, Eastern China

Abstract:

To determine reliable molecular thermal maturity parameters for prediction of the physical properties of biodegraded oils, a suite of oils including 11 biodegraded oils from Caoqiao oilfield and 5 non-biodegraded oils from Wangjiagang oilfield in Dongying depression in Bohai-bay basin, eastern of China were analyzed. The oils were selected in a wide range of viscosity in order to investigate the relation between the parameters and oil properties. The data show the effects of biodegradation on some molecular thermal maturity parameters: C₂₉ sterane parameters C₂₉20S/(20S+20R) and C₂₉ββ/(ββ+αα) increased apparently under heavy biodegradation (rank 6~7); parameters C₃₁22S/(22S+22R), C₃₂22S/(22S+22R), C₂₉3-methyl/C₂₉ 4-methyl, (C₂₈+C₂₉Tricyclics)/Ts and (C₂₈+C₂₉Tricyclics)/ (C₂₈+C₂₉Tricyclics +Ts) showed effects from heavy biodegradation (rank 6~7), and terpanes parameters Ts/(Ts+Tm), C₂₉Ts/(C₂₉Ts+C₂₉Tm) and aromatic C₂₀/(C₂₈+C₂₀), (C₂₀+C₂₁)/(C₂₀+C₂₁+C₂₆+C₂₇+C₂₈) and D(_3-6)/(D_3-6+ C₂₉ 4-methylstigmastane 20R showed no effect from heavy biodegradation. Based on the comparison, the molecular maturity parameters C₂₆ to C₂₈ triaromatic parameters C₂₆S/ (C₂₆S+C₂₈S), C₂₇R/(C₂₇R+C₂₈R), C₂₈/(C₂₆+C₂₇+C₂₈) and tricyclic terpanes parameters C₁₉/(C₁₉+C₂₃) were recommended to predict the physical properties of biodegraded oil for these parameters showed no effects from biodegradation(rank 6~7) and better relations with oil physical properties compared to other parameters. Some quantificational equations between these molecular thermal maturity parameters and the physical properties of biodegraded oils were inferred, which may assist in predicting the viscosity and API gravity of reservoired oils before production.

• Periodical: Advanced Materials Research (Volumes 524-527)
• Pages: 2069-2073
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.524-527.2069
• Online since: May 2012
• Authors: Zhong Hong Chen
• Keywords: Biodegraded Oils, Biomarker, Molecular Maturity Parameters, Oil Viscosity

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