中国南方地区奥陶系热液-岩溶改造型白云岩储层发育机理——以黔中地区下奥陶统为例

发布时间：2018-03-03 04:30

  本文选题：黔中隆起　切入点：奥陶系　出处：《海相油气地质》2017年02期 　论文类型：期刊论文

【摘要】：以黔中地区下奥陶统为例,通过野外剖面观测、实验分析等工作,揭示了白云岩的热液-岩溶改造特征,并探讨了其发育机理。研究区下奥陶统红花园组和桐梓组以白云岩为主,在白云岩构造裂缝和溶蚀孔洞中见白云石、方解石、沥青的充填,具有典型的斑马纹状构造。充填白云石为粗晶粒状的鞍形白云石,具有弯曲晶面和波状消光的特征,阴极发光呈现较强的红色。充填白云石的碳同位素δ~(13)C在-2.2‰~-0.8‰之间,平均值为-1.47‰,氧同位素δ~(18)O在-12.2‰~-7.6‰之间,平均值为-9.4‰,与围岩白云石相比明显偏轻。充填白云石的稀土元素具有典型的Eu正异常特征,δEu最高达91.9。根据地质演化背景和流体作用类型,奥陶系白云岩储层发育过程为:早奥陶世沉积过程中发生同生/准同生白云石化作用;中晚奥陶世至早志留世,受都匀运动影响,白云岩暴露至地表遭受岩溶作用,形成岩溶孔洞型白云岩储层;中泥盆世遭受构造热液进一步对白云岩进行的溶蚀改造,所形成的溶蚀孔洞为天然气的主要储集空间。
[Abstract]:Taking the Lower Ordovician in central Guizhou as an example, the characteristics of hydrothermal karst reconstruction of dolomite are revealed through field profile observation and experimental analysis. The development mechanism of dolomite, calcite and bitumen is mainly found in dolomite structural fractures and dissolution voids in the Lower Ordovician Red Garden formation and Tongzi formation, and the filling of dolomite, calcite and bitumen is found in the dolomite structural fractures and dissolution voids. It has a typical zebra grain structure. The dolomite filled with dolomite is a saddle-shaped dolomite with coarse grain shape, with the characteristics of curved crystal plane and wave-shaped extinction, and the cathodoluminescence is strong red. The carbon isotope 未 ~ (13) C of dolomite filled with dolomite is between -2.2 鈥，

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