四川盆地及其周缘晚震旦世—早寒武世早期区域抬升运动对岩溶储层发育的影响

晚震旦世—早寒武世早期,四川盆地震旦系灯影组形成上、下亚段2套区域性展布的风化壳岩溶储层,对其形成控制因素有待于深化研究。为此,基于野外露头剖面、钻井与地震等资料,系统分析了四川盆地及其周缘晚震旦世—早寒武世早期3期区域抬升运动对岩溶储层发育的建设作用。结果表明:1区域抬升运动分别发生于灯影组沉积早期末、震旦—寒武纪以及早寒武世早期;23期抬升运动均不同程度波及整个上扬子地台,致使抬升期上、下地层呈平行不整合接触,存在明显的沉积间断;3受地壳不均衡隆升作用的影响,各期抬升运动在不同地区的影响程度均有所差异,但总体表现为第一期北缘强于南缘,第二期西缘强于东缘,第三期东南缘强于西北缘的特征;43期抬升运动使灯影组上、下亚段各自形成一套为"碎屑岩层"所分隔的大面积展布的风化壳岩溶优质储层,为四川盆地灯影组大气区的形成奠定了坚实的物质基础。

Influences of regional uplifting during the Late Sinian - Early Cambrian on the development of karst reservoirs in the Sichuan Basin and its peripheral area

Two regional weathering crust karst reservoirs were developed in the upper and lower Sinian Dengying Fm in the Sichuan Basin during the Late Sinian Early Cambrian, and factors controlling their development are still unclear now. Outcrop observation, drilling and seismic data were integrated to systematically analyze the constructive impacts of three stage regional uplifting during the Late Sinian - Early Cambrian in the Sichuan Basin and its periphery. The following conclusions were obtained. (1) The regional uplifting occurred respectively at the end of Early Dengying period, the transition period from the Sinian to Cambrian, and the period of Early Cambrian, respectively. (2) These three stages of uplifting all influenced the whole Yangtz platform to some extent, resulting in the parallel unconformable contact between the formations formed before and after the uplifting and the obvious hiatus. (3) Because of the unequal uplifting of the crust, the degrees of influences of these three stages of uplifting are different at various margin areas. In general, the influences of the first time of uplifting is stronger in the northern margin than that in the south, that of the second time is stronger in the western margin than that in the east, while that of the third time is stronger in the southeastern margin than that in the northwest. (4) These three stages of uplifting resulted in the formation of extensive karst reservoirs of high quality in the upper and lower Dengying Fm, which are separated by a “clastic rock layer”. These karst reservoirs provide a solid basis for the formation of a large gas bearing area in the Dengying Fm, Sichuan Basin.