东海陆架盆地西湖凹陷孔雀亭区油气来源及运移方向

Source and migration direction of oil and gas in Kongqueting area, Xihu Sag, East China Sea Shelf Basin

  • 摘要: 孔雀亭区是西湖凹陷油气勘探重点区带,油气来源及运移方向不清限制了勘探的进一步拓展。基于油气特征及分布研究,通过开展烃源岩及原油生物标志化合物特征对比分析、天然气成熟度计算,综合厘定了油气来源;结合油气运移效应分析明确了原油及天然气运移方向。结果表明,孔雀亭区原油主要来自平湖组下段和宝石组烃源岩,平湖组中段及上段少量贡献,原油自斜坡内生油次洼向高部位运移,是原油优势运聚方向;天然气具有斜坡带本地烃源岩及西次凹双重来源,以西次凹贡献为主,天然气自斜坡低带向高带侧向运移,并沿断层与斜坡带烃源岩自生天然气混合呈现垂向运移特征,斜坡低部位是天然气勘探有利区带。

     

    Abstract: Kongqueting is a key exploration area in the Xihu sag of the East China Sea Shelf Basin. The ambiguity in source and migration direction of oil and gas has brought difficulties in efficient oil and gas exploration. This time, the source of oil and gas is jointly determined by the study of oil and gas characteristics and distribution patterns, the correlation of the biomarkers between source rocks and crude oil, and the calculation of the maturity of natural gas. In combination with the migration effect of oil and gas, the migration direction of crude oil and natural gas are discussed. The results suggest that the crude oil in Kongqueting area mainly comes from the source rocks of the Lower Pinghu Formation and Baoshi Formation, with a little from the Middle Pinghu Formation. Crude oil migrates mainly from the secondary depressions to the higher part of the slope for oil accumulation. In terms of natural gas, there are dual sources, one local source and one the source from the Western Subsag. The natural gas generated from the Western Subsag migrates from low zone to high zone along the slope, and mixed with natural gas generated by local source rock of the slope zone on the way, suggesting a pattern of vertical migration. Therefore, the low part of the slope is a potential area for natural gas exploration.

     

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