贵州赤水地区下侏罗统沉积特征

SEDIMENTARY CHARACTERS OF LOWER JURASSIC IN CHISHUI AREA OF GUIZHOU PROVINCE

为了弄清四川盆地东南部赤水地区侏罗系下统地层的沉积特征，评价其潜在的含油气性，开展了野外地质调查及相关室内研究。通过对野外露头和井下资料的系统研究，运用录井、测井及岩石薄片等宏观-微观分析手段，分析了区内下侏罗统的地层划分、岩性特征、沉积环境及沉积相等，认为下侏罗统主要属湖泊沉积环境，河流-冲积环境次之。湖泊相可划分为滨湖砂滩相、滨浅湖泥坪相、浅湖碳酸盐岩相和半深-深湖相。大安寨组半深-深湖相暗色泥页岩则是潜在的烃源岩；綦江组-马鞍山组滨湖砂滩相砂岩、东岳庙组浅湖碳酸盐岩相生屑灰岩为潜在的油气储层；珍珠冲组-大安寨组泥页岩可以作为有效区域盖层。认为下侏罗统的分布范围广，厚度大，又发育潜在的生储盖组合，具有较好的油气勘探前景。

In order to obtain sedimentary characters and to evaluate potential petrolifours natures of Lower Jurassic in Chishui area of Southeast Sichuan Basin, outdoor investigation and indoor study are both carried out. Based on outcrops study and subsurface information, by means of macro and micro analysis of well log, logging and thin section, this paper analyzes stratigraphic subdivision, lithological features, sedimentary environments and facies etc. , of Lower Jurassic in Chishui area, and proposes that sediments of Lower Jurassic majorly belong to lacustrine sediment environment, secondarily fluvial-alluvial environment. Lacustrine facies can be subdivided into onshore sands facies, onshore-offshore corcagh facies, shallow lake carbonate facies and quasi-deep to deep lake facies. The potential source rock is the dark shale of quasi-deep to deep lake facies from Da＇ anzhai Formation （J1dn）. The potential reservoirs are sandstone of onshore sands facies from Qijiang-Ma＇ anshan Formation （ J1 q-J1 m ） , as well as bioclastic limestone of shallow lake carbonate facies from Dongyuemiao Formation （ J1 d ）. Mud shale from Zhenzhuchong-Daanzhai Formation （J1zh-J1dn） is an effective regional cover. This paper concludes that there is good exploration potential for strata of Lower Jurassic with the characteristics of wide distribution, large thickness and potential generation-accumulation-cover assemblages.