四川盆地西部二叠系多期台缘带油气勘探潜力

doi:10.13745/j.esf.sf.2022.8.22

摘要/Abstract

摘要：

四川盆地西部二叠纪时期位于稳定克拉通边缘,受到海西运动、东吴运动和峨眉地裂运动的共同作用,发生构造-沉积分异。本文采用构造控盆、盆地控相、相控成藏要素组合的研究思路,在川西地区开展新一轮研究工作,揭示了二叠纪构造-沉积分异对油气成藏的控制作用,明确川西地区海相碳酸盐岩油气勘探潜力。盆地二叠纪以拉张伸展背景为主,总体呈现“南部隆升、西部裂陷、北部拉张”的沉积格局。二叠纪多期构造运动共同导致了川西地区一系列台内裂陷的形成,叠加二叠纪时期海平面变化,控制了栖霞至长兴期的多期台缘发育。川西北地区发育北东—南西向和北西—南东向两组断裂体系控制该区岩相古地理格局,其中龙门山断裂带主要控制了泥盆纪至二叠纪栖霞期沿上扬子台地西北缘发育台缘带,呈北东向展布。茅口至长兴期台缘带受克拉通边缘及台内裂陷共同控制,在川西地区呈北东向展布,梓潼—老关庙地区沿裂陷发育呈北西向展布,在剑阁一带,栖霞、茅口、吴家坪和长兴组多期台缘带叠置发育。川西地区二叠纪多期台缘控制了多层系优质滩相储层和礁储层叠置发育,是川西地区二叠系规模孔隙型储层发育的主控因素。多期古裂陷、多期台缘带和成藏期大型古隆起三元素耦合有利于油气规模聚集成藏。川西多层系台缘带具有纵向叠置,平面呈北东向大面积展布的特征,具备万亿规模资源潜力,是四川盆地海相碳酸盐岩重要勘探接替领域。

关键词: 四川盆地西部, 海西期, 二叠系, 台缘带, 油气勘探潜力

Abstract:

Situated in stable cratonic margins during the Permian the western Sichuan Basin experienced tectonic-sedimentary differentiation under jointly the actions of the Hercynian movement, Dongwu movement and Emei rift. Adopting the research idea that tectonic movement controls basin, basin controls facies, facies control reservoir-forming elements,a new round of research is carried out in the western Sichuan Basin to investigate the control of petroleum accumulation by Permian tectonic-sedimentary differentiation and determine the exploration potential of marine carbonate rocks in the western Sichuan Basin. During the Permian, the Sichuan Basin is dominated by tensional/extensional tectonic activities and a general sedimentary pattern of “uplift in the south, rift in the west, and tension in the north” is revealed. The Permian multi-stage tectonic movements lead to the formation of a series of intra-platform rifts in western Sichuan, which, combined with the Permian sea-level change, control the multi-stage platform-margin development from the Qixia to Changxing formations. The NE-SW and NW-SE fault systems developed in the northwestern basin control the lithofacies paleo-geographic pattern of this area. Among them, the Longmenshan fault belt largely controls the development of platform margins N-E along the northwestern edge of the upper Yangtze platform from the Devonian to Permian Qixia periods. From the Maokou to Changxing periods, the platform margins—spreading N-E in the western Sichuan Basin and N-W along rifts in the Zitong-Laoguanmiao areas—are jointly controlled by cratonic margins and intra-platform rifts, and the multi-stage platform margins of the Qixia, Maokou, Wujiaping and Changxing formations are superimposed in the Jiange area. In the western Sichuan Basin, the Permian multi-stage platform margins control the superposition of multi-layer, high-quality beach facies reservoirs and reef reservoirs, which is the main factor controlling the development of large-scale Permian porous reservoirs in this area. The coupling of multi-stage paleo-rift depression, multi-stage platform-margin zones and large-scale paleo-uplift in the reservoir-forming stage is conducive to the large-scale oil and gas accumulation. Vertically superimposed and spreading N-W over a wide range the multi-layer platform margins of western Sichuan possess trillion-ton petroleum resource potential and are an important replacement exploration target for marine carbonate rocks in the Sichuan Basin.

Key words: western Sichuan Basin, Hercynian, Permian system, platform-margin zone, oil and gas exploration potential

中图分类号:

P624

杨雨, 文龙, 陈聪, 汪华. 四川盆地西部二叠系多期台缘带油气勘探潜力[J]. 地学前缘, 2023, 30(1): 1-10.

YANG Yu, WEN Long, CHEN Cong, WANG Hua. Oil and gas exploration potential of the Permian multi-stage platform-margin zone, western Sichuan Basin.[J]. Earth Science Frontiers, 2023, 30(1): 1-10.

图/表 9

图1 四川盆地构造分区图

Fig.1 Structural partition in Sichuan Basin

图2 扬子地块西部二叠纪大型断裂发育平面位置示意图(据文献[6]修编)

Fig.2 Planar location of large-scale Permian fault,western Yangtze block. Modified after [6]

图3 四川盆地及周缘二叠纪构造动力机制示意图(剖面位置见图2)

Fig.3 Dynamic mechanism of the Permian structure in Sichuan Basin and its periphery(profile location as seen in Fig.2)

图4 四川盆地二叠纪各期沉积相图 a—四川盆地栖霞期沉积相图;b—四川盆地茅二期沉积相图;c—四川盆地吴家坪期沉积相图;d—四川盆地长兴期沉积相图。

Fig.4 Diagrams of sedimentary facies in the Permian, Sichuan Basin

图5 川西地区二叠系多期台缘带沉积相剖面图

Fig.5 Sedimentary-facies profile in the multiple-stage Permian platform margin, western Sichuan Basin

图6 四川盆地及周缘寒武系筇竹寺组烃源岩厚度与二叠系多层系台缘带叠合图

Fig.6 Superimposition of the thickness of source rock in the Cambrian Qiongzhusi Formation and the multiple-stage Permian platform margin in Sichuan Basin and its periphery

图7 川西地区二叠系多期台缘带储层特征 a—LG2井,长兴组,6 126 m,生物灰岩,晶间(溶)孔;b—LG28井,长兴组,6 025.9 m,生物灰岩,晶间(溶)孔;c—ST12井,吴家坪组, 6 684 m,细晶云岩,晶间溶孔;d—LX1井,吴家坪组,6 889 m,云岩见残余颗粒,晶间孔;e—ST7井,茅口组,7 386 m,细晶云岩,晶间溶孔;f—SYX133井,茅口组,7 304 m,细晶云岩;g—ST12井,栖霞组,7 086 m,粗晶云岩,晶间溶孔; h—ST3井,栖霞组,7 448.5 m,粗晶云岩,晶间溶孔;i—PT1,栖霞组,6 779.84 m,细晶云岩,晶间溶孔。

Fig.7 Reservoir Characteristics of the multiple-stage Permian platform margin, western Sichuan Basin

图8 川西地区多期台缘带叠置关系、源储配置及油气充注模式示意图

Fig.8 Overlapping relation, source-reservoir assemblage, and hydrocarbon-charging mode in the multiple-stage platform margin, western Sichuan Basin

图9 川西地区多期台缘带成藏要素综合评价图

Fig.9 Comprehensive evaluation on the main factors affecting reservoir forming in the multiple-stage platform margin, western Sichuan Basin

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