川东北地区大中型气藏天然气特征及气源

doi:10.11743/ogg20110608

摘要/Abstract

摘要：

四川盆地东北部下三叠统飞仙关组、上二叠统长兴组内发现了丰富的天然气资源,展现了良好的潜力。结合川东北地区烃源岩特征,对比分析长兴-飞仙关组天然气组分、同位素待征与石炭系气藏的异同,从而确定其主力烃源岩层;对长兴-飞仙关组储层进行密集采样,分析其有机碳值,进而定量评价储层沥青的含量;同时根据物质守恒原理,计算出普光古油藏裂解生成的天然气总量。研究发现,龙潭组烃源岩是长兴-飞仙关组气藏的主力烃源岩,干酪根裂解气超过原油二次裂解气的贡献,是气藏的首要气源类型;普光气藏的古油藏裂解生成天然气总量为3 610×10⁸ m³,其贡献不能满足普光大型气藏的形成,进一步验证了关于长兴-飞仙组气藏首要气源为干酪根裂解气的结论。

关键词: 同位素, 储层沥青, 烃源岩, 天然气, 普光气藏, 川东北

Abstract:

Abundant natural gas resources have been discovered in the Lower Triassic Feixianguan Formation and Upper Permian Changxing Formation in northeast Sichuan Basin,revealing good potential for natural gas exploration.Based on an analysis of the characteristics of hydrocarbon source rocks in northeast Sichuan Basin,we identify the major hydrocarbon source rocks by the comparision of the natural gas composition and isotope features of the Changxing and Feixianguan formations with that of the Carboniferous reservoirs.The Changxing and Feixianguan formations were densely sampled to measure their organic carbon contents and to quantitatively calculate bitumen contents of the reservoirs.Meanwhile,the total gas volume from oil-cracking in Puguang ancient oil reservoirs were calculated based on the principle of conservation of matter.The study shows that the Longtan Formation source rocks are the major source rocks for Changxing and Feixianguan formation gas reservoirs.The kerogen-cracking contributed more gas than secondary cracking of crude oil,thus gas from kerogen-cracking is the primary gas source.The total gas generated from oil cracking is 361 BCM in the Puguang gas pool,which is not large enough for the forming of the huge Puguang gas pool.This further proves the conclusion that the major gas for the Changxing and Feixianguan formation gas reservoirs comes from kerogen-cracking gas.

Key words: isotope, reservoir bitumen, source rock, natural gas, Puguang gas pool, northeast Sichuan Basin

中图分类号:

TE122.1

王强,徐立恒,陈践发. 川东北地区大中型气藏天然气特征及气源[J]. 石油与天然气地质, 2011, 32(6): 867-872,881. doi: 10.11743/ogg20110608 Wang Qiang,Xu Liheng,Chen Jianfa. Characteristics and origin of natural gas in large- and medium-sized gas reservoirs in northeast Sichuan Basin[J]. Oil & Gas Geology, 2011, 32(6): 867-872,881. doi: 10.11743/ogg20110608

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