中上扬子区志留系龙马溪组页岩气勘探区优选

将中上扬子区志留系龙马溪组页岩与具有相似构造沉积背景的Fort Worth盆地Bar-nett页岩进行对比研究,揭示龙马溪组页岩与Barnett页岩的相似性和变形的差异性。结果表明,龙马溪组页岩与Barnett页岩具有相似的沉积背景、岩性组合和隆升演化模式,但龙马溪组页岩经历了多期构造变形的改造和叠加,不同构造单元的变形强度存在明显的差异,形成了不同的断裂组合及各种不同类型、不同规模的裂缝,构造变形很大程度上制约了中上扬子区龙马溪组页岩气的成藏和破坏。根据龙马溪组页岩现今的残存厚度,结合构造变形的强度,提出川南和川东鄂西页岩发育带均为有利的页岩气勘探潜力区带,但川南页岩发育带优于川东鄂西页岩发育带。两个有利勘探区带内变形相对较弱、远离断裂带和原生裂缝不甚发育区是页岩气富集成藏的有利区域,应为页岩气藏勘探的首选目标区。

Preferred targets of the shale gas from Silurian Longmaxi Formation in middle-upper Yangtze of China

This paper makes a comparison between the Silurian Longmaxi Formation shale and the Mississippian Barnett Shale and in the Fort Worth Basin with similar tectonic and depositional settings.The result reveals the similarity and deformation differences between the Longmaxi Formation shale and the Barnett Shale.The research shows that the Longmaxi Formation shale and the Barnett Shale have the similar depositional setting,lithologic association and uplifting evolution model,but the Longmaxi Formation shale experienced polyphase deformations reconstruction and superimposition and formed different tectonic units with obvious differences in tectonic deformation,different fault-complex patterns and different types and scales of fractures.The tectonic deformation plays a very important role in the hydrocarbon accumulation and breakage of the Longmaxi Formation shale gas in the middle-upper Yangtze area of China.According to the residual thickness of the Longmaxi Formation shale and combined with the intensity of the tectonic deformation,the preferred potential zones of shale gas are suggested.They are the shale development area of South Sichuan and East Sichuan-West Hubei,but that of the South Sichuan is better.These areas with weakly deformation and far away from faults and absence of fractures may be the best targets for the shale gas exploration in both preferred exploration zones.