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塔里木盆地塔中4油田位于塔中构造较高部位,具有显著不同于周边原油的特征.采用高分辨率质谱、色谱-质谱等对原油成因进行了调查.GC/MS分析表明,塔中4油田石炭系原油中链烷烃(指示未降解-轻度降解)极其发育,同时检测到丰富的降解三环萜烷及25-降藿烷系列(指示强烈生物降解),反映该区油气具有多期充注特征.高分辨率质谱分析显示,塔中4油田原油中硫化物分布正常,低等效双键数(DBE)硫化物不太发育,天然气组成与碳同位素也未显示异常,反映石炭系原油可能未受TSR作用影响.观察到塔中4油田原油中硫化物组成与分布特征多数与下奥陶统原油相近,指示两者可能有一定成因联系.混源模拟实验显示,下奥陶统原油混入可导致塔中4油田原油出现高芳香硫特征.地质地球化学综合研究认为,塔中4油田原油中芳香硫异常与深源油气混合有关,与TSR作用关系不明显.
The Tazhong 4 oilfield in the Tarim Basin is located in a higher part of the Tazhong structure and has characteristics that are significantly different from those of the surrounding crude oil.The genesis of the crude oil was investigated by high resolution mass spectrometry and mass spectrometry.GC / MS analysis showed that the Tazhong 4 oilfield The paraffins (indicating undegraded to mildly degraded) in the Carboniferous crude oil are extremely well developed, while the rich series of degraded tricyclic terpanes and 25-norhopane series (indicating strong biodegradation) were detected at the same time, indicating that oil and gas in this area have multi-phase charge Note that high-resolution mass spectrometry analysis showed that the distribution of sulfide in the crude oils of Tazhong 4 oilfield is normal, the low equivalent double bond number (DBE) sulfides are not well developed, and the composition and carbon isotope of natural gas are not abnormal, reflecting that the Carboniferous crude oil May not be affected by the TSR effect.It is observed that most of the sulfide compositions and distributions in the crude oil from Tazhong 4 oilfield are similar to that of the Lower Ordovician oil, indicating that there may be some genetic relationship between the two.Since mixed source simulations show that the Lower Ordovician crude oil Mixing can lead to high aromatic sulfur content in the crude oil of Tazhong 4 oilfield.Geological and geochemical comprehensive studies suggest that the anomalous sulfur anomalies in the crude oil of Tazhong 4 are related to the mixing of deep-sea oil and gas, but not to TSR.