四川盆地东部海相二叠系油苗的发现及其地质意义

作    者:刘岩,钟宁宁,邵瑞奇,田永晶,朱雷,马永强
单    位:中国石油大学(北京)油气资源与探测国家重点实验室
基金项目:
摘    要:
在四川盆地东部古生界地层发现大量天然气资源,鲜有原油发现。重庆天府 磨心坡煤矿下二叠统茅口组石灰岩上部地层裂隙发现沿层间裂隙随水渗出的黄绿色液态轻质油苗。研究表明院油苗碳数分布较窄,为C4~C26,具有明显的姥鲛烷优势,Pr/Ph值为1.64,δ13C 值为-26.2‰;油苗所反映的成熟度较高,折算Ro约为1.6%,一维盆地模拟验证二叠系的热演化程度可达与之相当的热演化程度。综合研究认为油苗与二叠系煤系地层关系密切。油苗的发现表明,在四川盆地古生界整体高过成熟的大背景下,某些成熟度相对较低,保存条件适宜的区域仍有发现一些中小型油藏的可能,这对四川乃至南方古生界油气勘探具有一定的启示意义。
关键词:四川盆地东部;海相地层;二叠系;油苗;成熟度;碳同位素

Light Oil Show Discovered in Permian Marine Limestone in the East Part of Sichuan Basin and Its Geological Significance

Author's Name: Liu Yan,Zhong Ningning,Shao Ruiqi,Tian Yongjing,zhu Lei, Ma Yongqiang
Institution: State Key Laboratory of Petroleum Resource and Prospecting,China University of Petroleum, Changping, Beijing
Abstract:
There is abundant natural gas but less oil accumulation in Palaeozoic and Triassic marine reservoirs in the east part of Sichuan Basin. Recently,some yellow greenish light crude oil show was discovered in fissures of marine Lower Permian Maokou limestone at Moxinpo Coal Mine in Chongqing. The oil has been analyzed by a series of geological and organic geochemistry methods. The distribution of n-alkane in aliphatic fraction of the oil ranges from n-C4 ton-C26 with obvious pristane preference (Pr/Ph=1.64). Relatively high Ro (about 1.6%) of the calculated oil maturity is consistent with the measured vitrinite reflectance of the Permian coal at Moxinpo. The δ13C is -26.2‰, which is similar to those from Permian Longtan shale and coal. It is considered that the oil in limestone fissures is mostly derived from the marine Permian coal measure strata, including some contributions of continental organic matter. The accumulation of the hydrocarbon needs to be further studied. The discovery of the oil show hints possible industrial hydrocarbon accumulation in some relative low mature reservoirs among high mature areas of Sichuan Basin.
Keywords: Oil show; Permian; Marine formation; Maturity; Carbon isotope; Sichuan Basin
投稿时间: 2009-05-08  
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