The controls on the composition of biodegraded oils in the Liuhua11-1 Oilfield, Pearl River Mouth Basin, South China Sea  

作　　者：Jiang Kaixi He Wenxiang Xiang Nian Peng Li Han Changchun Guo Qingzheng 

机构地区：[1]CNOOC Energy Technology & Services Unconventional Oil & Gas Technology Research Institute [2]School of Earth Environment and Water Resources, Yangtze University [3]CNOOC Central Laboratory [4]Research Institute of Shaanxi Yangchang Petroleum (Group)Co. Ltd.

出　　处：《Chinese Journal Of Geochemistry》2015年第3期320-329,共10页中国地球化学学报

基　　金：funded by the Major National Science and Technology Project of China (Grant No. 2011ZX05033004-003)

摘　　要：(1) The geochemical characteristics of extracted oils in three oil columns from the Liuhua11-1 Oilfield in the Pearl River Mouth Basin of South China Sea were analyzed in detail. The results show that the oil of Liuhua 11-1 Oilfield is generated from a single source rock, and belongs to maturate oil and their maturities have little difference.(2) The characteristics of saturated hydrocarbon gas chromatography,bulk composition, concentrations of biomarkers and gas chromatography–mass spectrometry of saturated hydrocarbon indicate that all samples studied were biodegraded, and the maximal level of biodegradation is less than PM level 6.(3) Bulk composition and the degree of biodegradation presented excellent gradient variations in the oil columns, and the highest degradation rates occurred at or near the oil–water contact(OWC). The key biomarkers of steranes and terpanes and maturity parameters of saturated hydrocarbon were not affected by degradation, which means that they are stable in slight to moderately biodegraded oils. Across the oilfield, the degree of biodegradation of LH11-1-3 was higher than that of LH11-1-1A and LH 11-1-4 in general.(4) We infer that the strong hydrodynamic conditions(tectonic control) and high reservoir temperatures(50–65 °C) are the primary controllers of the degree of oil biodegradation in the Liuhua 11-1 Oilfield and the late hydrocarbon accumulation may also have an important effect. The bulk composition and degree of biodegradation with excellent gradient variations in the oil columns were obviously controlled by the vertical distance from its in situ place to OWC. The highest supply of nutrient at the OWC results in high abundance of microorganisms and the highest degradation rate. And the lateral variation in level of biodegradation across the oil reservoir may be mainly control by the salinity of bottom water, the supply of nutrient and the energy of the bottom water.（1） The geochemical characteristics of extracted oils in three oil columns from the Liuhua11-1 Oilfield in the Pearl River Mouth Basin of South China Sea were analyzed in detail. The results show that the oil of Liuhua 11-1 Oilfield is generated from a single source rock, and belongs to maturate oil and their maturities have little difference. （2） The characteristics of saturated hydrocarbon gas chromatography, bulk composition, concentrations of biomarkers and gas chromatography-mass spectrometry of saturated hydrocarbon indicate that all samples studied were biodegraded, and the maximal level of biodegradation is less than PM level 6. （3） Bulk composition and the degree of biodegradation presented excellent gradient variations in the oil columns, and the highest degradation rates occurred at or near the oil-water contact （OWC）. The key biomarkers of steranes and terpanes and maturity parameters of saturated hydrocarbon were not affected by degradation, which means that they are stable in slight to moderately biodegraded oils. Across the oilfield, the degree of biodegradation of LH 11-1-3 was higher than that of LH11-1-1A and LH 11-1-4 in general. （4） We infer that the strong hydrodynamic conditions （tectonic control） and high reservoir temperatures （50-65 ℃） are the primary controllers of the degree of oil biodegradation in the Liuhua 11-1 Oilfield and the late hydrocarbon accumulation may also have an important effect. The bulk composition and degree of biodegradation with excellent gradient variations in the oil columns were obviously controlled by the vertical distance from its in situ place to OWC. The highest supply of nutrient at the OWC results in high abundance of microorganisms and the highest degradation rate. And the lateral variation in level of biodegradation across the oil reservoir may be mainly control by the salinity of bottom water, the supply of nutrient and the energy of the bottom water.

关 键 词：流花11-1油田 生物降解油 主控制器 珠江流域 南中国海 组成 气相色谱-质谱法 生物标志物 

分 类 号：P618.13[天文地球—矿床学]