四川盆地德阳—安岳台内裂陷与震旦系勘探方向

Deyang-Anyue Interplatform Rift in Sichuan Basin and Its Direction of Exploration in Sinian

阐明了四川盆地德阳—安岳台内裂陷的基本特征及形成演化,探讨了台内裂陷对震旦系油气成藏的控制作用,取得4项成果认识:(1)台内裂陷呈南北向展布,长300 km,宽50～230 km,面积60 000 km^2,其中沉积了深水的泥页岩和泥质白云岩。(2)台内裂陷的形成与罗迪尼亚期超级大陆的裂解、断陷作用和差异沉积作用三个因素有关,它发育于晚震旦世灯影早期,止于早寒武世筇竹寺中晚期,经历四次拉张、三次暴露剥蚀以及快速充填消亡等8个演化阶段。(3)台内裂陷发育灯影组三段、麦地坪组和筇竹寺组三套烃源岩,是烃源岩发育中心和生烃、供烃中心;台内裂陷两侧在震旦纪发育了灯影组二段、灯影组四段两套大面积分布的白云岩储层,优质储层沿台缘带展布;源岩与储层侧向接触,构成侧向供烃、侧向封堵的成藏组合,有利于油气成藏富集。(4)提出"沿台内裂陷两侧台缘带勘探"的震旦系勘探思路,近期勘探可首选东侧台缘带,遂宁—剑阁区带的九龙山构造和荣昌—泸州区带的阳高寺构造可成为突破口。

The essential characteristics of Deyang-Anyue interplatform rift and its formation and evolution are illustrated in the paper. And it is also discussed the controls of Deyang-Anyue interplatform rift on the Sinian reservoir formation. Then four achievements were obtained, as follows：（1）The interplatform rift shows a north-south distribution, and covers an area of 60000 km^2, with a length of 300 km, and a width of 50～230 km. Deep-water shale and argillaceous dolomite were deposited in the trough.（2）The interplatform rift forming is closely related to three factors of continent breaking up, faulting and differential sedimentation, and experienced eight tecotinic evolution stages from late Sinian（early deposition of Dengying Fromation） to early Cambrian（middle-late deposition of Qiongzhusi Formation）, including four times extensional movement, three times exposure-denudation, and a rapid filled decaying stage.（3）Three sets of source rocks, including three members separately from Dengying Formation, Maidiping Formation and Qiongzhusi Formation, developed in the interplatform rift, where is the hydrocarbon generating center and the hydrocarbon supplying center. Dolomite reservoir of member 2 and member 4 of Dengying Formation developed with large area on both sides of the rift, and the high quality reservoir distributed along interplatform margins. Source rock and reservoir contact laterally.（4）It is put forward that the zones along the both sides of interplatform rift are the most prospective region of Sinian exploration. And the eastern side of it is preferred in recent exploration. It is predicted that Jiulongshan structure in Suining-Jiange area and Yanggaosi structure in Rongchang-Luzhou area should be the next exploration targets.