Shale oil potential of lacustrine black shale in the Eocene Dongying depression: Implications for geochemistry and reservoir characteristics
Shale oil potential of lacustrine black shale in the Eocene Dongying depression: Implications for geochemistry and reservoir characteristics
复制标题
东营凹陷始新统湖相黑色页岩的页岩油潜力：地球化学和储层特征的意义
DOI：
10.1306/01251715249
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发表时间：
2017-11-01
期刊：
影响因子：
3.5
通讯作者：
Wang, Yongshi
中科院分区：
文献类型：
--
作者：
Liang, Chao;Cao, Yingchang;Wang, Yongshi
通过岩心薄片和场发射扫描电镜观察，结合X射线衍射、物性测试和地球化学指标，详细描述了东营凹陷始新统湖相页岩的地球化学特征和储层特征。始新统沙河街组Es 4s-Es 3x页岩段主要为碳酸盐、粘土矿物和石英。识别出六种岩相：（1）层状灰岩（富有机质层状灰岩和贫有机质层状灰岩），（2）层状泥灰岩，（3）层状钙质泥岩，（4）层状白云质泥岩，（5）层状石膏泥岩，（6）块状泥岩。来自三个取芯威尔斯井的Es 4s-Es 3x页岩样品具有在0.58至11.4重量%范围内的总有机碳（TOC）含量。%，平均为3.17wt. %.生烃潜力（游离烃[S1] +干酪根裂解烃[S2]）值为2.53 ~ 87.68 mg/g，平均值为24.19 mg/g。东营凹陷沙四段-沙三段泥质有机质含量高，具有很好或极好的生烃潜力。有机显微组分主要为腐泥岩（高达95%）。氢指数（S2/TOC）与热解产物最高产率温度（Tmax）的关系表明，有机质主要是I型干酪根，其中含有高比例的可转化有机碳。Es 4s-Es 3x页岩是热成熟的，在油窗内，镜质组反射率值范围为0.46%至0.74%，最大温度值范围为413摄氏度至450摄氏度，平均温度为442摄氏度。泥页岩中含有粒间孔隙、有机质孔隙、溶解孔隙、晶内孔隙、层间裂缝、构造裂缝和异常压力裂缝。原生基质孔隙储集空间主要是有机质热成熟过程中形成的次生重结晶晶间孔和溶解孔。有机质含量和有效厚度是富有机质页岩生烃的主要因素。储集能力与孔隙空间的规模、丰度和连通性有关，而孔隙空间的规模、丰度和连通性受岩相、矿物组成、TOC含量和微裂缝特征的控制。
The geochemistry and reservoir characteristics of the lacus-trine shale in the Eocene Dongying depression are described in detail based on thin-section and field-emission-scanning electron microscope observations of well cores combined with x-ray diffraction, physical property testing, and geochemical indicators. The Eocene Shahejie (Es) Formation Es4s-Es3x shale member is predominantly carbonate, clay minerals, and quartz. Six lithofacies were identified: (1) laminated limestone (organic-rich laminated limestone and organic-poor laminated limestone), (2) laminated marl, (3) laminated calcareous mudstone, (4) laminated dolomite mudstone, (5) laminated gypsum mudstone, and (6) massive mudstone. The Es4s-Es3x shale samples from three cored wells had total organic carbon (TOC) contents in the range of 0.58 to 11.4 wt. %, with an average of 3.17 wt. %. The hydrocarbon generation potential (free hydrocarbons [S1] + the hydrocarbons cracked from kerogen [S2]) values range from 2.53 to 87.68 mg/g, with an average of 24.19 mg/g. The Es4s-Es3x shale of the Dongying depression has a high organic-matter content with very good or excellent hydrocarbon generation potential. The organic maceral composition is predominantly sapropelinite (up to 95%). The hydrogen index (being S2/TOC) versus the maximum yield temperature of pyrolysate (Tmax) indicates that the organic matter is predominantly type I kerogen, which contains a high proportion of convertible organic carbon. The Es4s-Es3x shale is thermally mature and within the oil window, with the vitrinite reflectance values ranging from 0.46% to 0.74% and the T-max value ranging from 413 degrees C to 450 degrees C, with the average being 442 degrees C. The shale contains interparticle pores, organic-matter pores, dissolution pores, intracrystalline pores, interlaminar fractures, tectonic fractures, and abnormal-pressure fractures. The primary matrix pore storage is secondary recrystallized intercrystal pores and dissolution pores that formed during thermal maturation of organic matter. The TOC content and effective thickness of the organic-rich shales are the primary factors for hydrocarbon generation. The reservoir capacity is related to the scale, abundance, and connectivity of pore spaces, which are controlled by the characteristics of the lithofacies, mineral composition, TOC content, and microfractures.