鄂西地区下寒武统水井沱组沉积特征及岩石组构非均质性分析

Abstract

在详细调研国内外页岩气储层非均质性研究的基础上，对鄂西地区水井沱组开展了沉积特征及页岩储层非均质性的分析。研究表明：水井沱组总体为一套细粒碎屑岩沉积，可划分为2个三级层序，Sq1时期沉积类型主要为碎屑岩陆棚相深水陆棚亚相泥质陆棚微相沉积，Sq2时期沉积类型主要为混积陆棚相浅水陆棚亚相灰质陆棚微相沉积。宏观上海侵体系域主要发育碳质页岩；高位体系域主要发育钙质、粉砂质泥页岩。微观上海侵体系域中页岩储层具有粘土矿物和有机碳含量向上逐渐升高，脆性矿物含量降低的特征；高位体系域中页岩储层变化规律则相反。页岩气储层特征分布的非均质性可能受到沉积时期海平面升降变化、物源供给以及生物作用的控制，也受到成岩作用、构造作用的影响。 Based on the detailed study of the heterogeneity of shale gas reservoirs at home and abroad, the analysis of sedimentary characteristics and shale reservoir heterogeneity were carried out in Shuijingtuo Formation in western Hubei. The results show that the sediments of the Shuijingtuo Formation are divided into two third-order sequences, and the sedimentary types of the Sq1 sediments are mainly clastic rocks. The Sq2 sedimentary types of the period are mainly mixed silt pond micro-facies sediments. At the macro level, the transatlantic system mainly develops carbonaceous shale. The high system tract mainly develops calcium and silty mud shale. In microcosmic, the shale reservoir in the transgressive system has the characteristics of increasing clay mineral content and organic carbon content, and decreasing the content of brittle mineral content. The variation of shale reservoir in high system tract is opposite. The heterogeneity of the characteristics of shale gas reservoirs may be controlled by sea level rise and fall, source supply and biological action during the depositional period, and also affected by diagenesis and tectonism.