四川盆地涪陵焦石坝地区黑色页岩非均质性特征及控制因素

Heterogeneity characteristics and controlling factors of black shale in Jiaoshiba, Fuling, Sichuan Basin

  • 摘要: 页岩的宏观和微观多重非均质性研究是页岩气勘探开发的核心内容之一。四川盆地涪陵焦石坝地区黑色页岩可划分为2个三级层序,9个小层,其宏观非均质性主要表现为:页理缝总体呈现自下而上先减少后增加的趋势;砂质条带与页理呈负相关性,表现为先增加后减少;黄铁矿总体呈现出自下而上逐渐减少的特征;笔石种类则显示出海侵体系域以双笔石科为主,早期高位和晚期高位体系域逐渐过渡至以单笔石科为主,笔石丰度则表现出从下至上逐渐减少的趋势。其微观非均质性主要表现为:有机碳含量由下至上具有逐渐减小的趋势,在海侵体系域内含量最高;黏土矿物含量的变化由下至上逐渐增加。整体来看,生物、等深流、陆源3种沉积作用共同控制了焦石坝地区黑色页岩的非均质性。

     

    Abstract: The study of macroscopic and microscopic heterogeneity of shale is one of the core aspects of shale gas exploration and development. The black shale in Jiaoshiba area in Fuling of Sichuan Province can be divided into two third-level sequences and nine sub-layers. The macroscopic heterogeneity mainly shows as follows. Laminations decrease first and then increase from bottom to top, sandy bands first increase and then decrease, while pyrites gradually decrease. Graptolithina in the transgressive system tract is mainly diplograptus type, while those in the early and late high system tracts are mainly monograptus type. Graptolithina abundance gradually reduces from bottom to top. The microscopic heterogeneity mainly shows as follows. TOC content in the transgressive system tract is the highest, and then decreases upwards, while clay mineral content gradually increases from bottom to top. On the whole, three kinds of sedimentation, bio-current, isochronous flow and terrigenous source, jointly controlled the heterogeneity of black shale in the Jiaoshiba area.

     

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