| 鄂西宜昌地区五峰组-龙马溪组页岩储层特征及其脆性评价 |
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| 引用本文： | 陈林,陈孝红,张保民,张国涛,李海,吕嵘,陆永潮,林卫兵.鄂西宜昌地区五峰组-龙马溪组页岩储层特征及其脆性评价[J].地质科技通报,2020,39(2):54-61. |
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| 作者姓名： | 陈林 陈孝红 张保民 张国涛 李海 吕嵘 陆永潮 林卫兵 |
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| 基金项目： | 国家重大科技专项2016ZX05034001-002中国地质调查局地质调查项目DD20160194 |
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| 摘 要： | 依据鄂西宜昌地区五峰组-龙马溪组页岩X射线衍射全岩分析、X射线衍射黏土矿物分析、物性分析、含气性测试和地球物理测井等资料，对区内页岩储层发育特征和页岩脆性特征进行了研究和综合评价。结果表明:宜昌地区五峰组-龙马溪组页岩依次主要由石英、黏土矿物、长石、白云石、方解石、黄铁矿等组成；具有自底部“高硅、低黏土”页岩向上过渡为“低硅、高黏土”页岩的发育特征。页岩孔隙度主要为1.01%~1.77%，平均1.29%，渗透率主要为0.001×10-3~0.843×10-3 μm2，平均0.234×10-3 μm2，属于低孔特低渗储层；五峰组-龙马溪组下部页岩含气量普遍大于1 m3/t，厚度可达20 m。脆性矿物含量法脆性分析结果显示，页岩脆性指数分布于39.6%~89.6%之间，平均55.4%，其中底部10 m厚的页岩脆性指数均大于60%，利于储层压裂改造后形成复杂的裂缝网络系统。弹性参数法脆性分析结果显示，五峰组-龙马溪组页岩杨氏模量主要为25.2~67.5 GPa，平均38.9 GPa；泊松比主要为0.177~0.327，平均0.297；脆性指数主要介于8.5%~97.3%之间，平均33.2%；其中底部13 m厚的页岩具有典型高杨氏模量、低泊松比和高脆性指数的特征。页岩脆性综合评价结果表明，五峰组-龙马溪组底部9 m厚的页岩发育相对最优杨氏模量和泊松比条件，脆性属于中-高等程度，造缝能力强，可压裂性好。将页岩段划分为4类可改造储层，其中底部2 714.4~2 723.4 m段页岩具有泊松比相对最小、含气性最好、脆性最优和有机质含量高等特征，构成研究区最优改造层段。
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| 关 键 词： | 五峰组-龙马溪组 矿物组成 脆性评价 宜昌地区 |
| 收稿时间： | 2019-07-10 |
Reservoir characteristics and brittleness evaluation of Wufeng Formation-Longmaxi Formation shale in Yichang area,Western Hubei Province |
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| Abstract: | Based on the data of X-ray diffraction (XRD) whole rock analysis, X-ray diffraction clay mineral analysis, physical analysis, gas-bearing test and geophysical logging of the Wufeng Formation-Longmaxi Formation shale in Yichang area, the development characteristics and brittleness characteristics of the shale reservoirs in the area are studied and evaluated comprehensively. The results show that the shale of Wufeng Formation-Longmaxi Formation in Yichang area is mainly composed of quartz, clay minerals, feldspar, dolomite, calcite and pyrite, and has the characteristics of high silica, and low clay in the bottom and low silica and high clay in the upper layer. The shale porosity mainly ranges from 1.01% to 1.77%, with an average of 1.29%, permeability mainly ranges from 0.001×10-3 μm2 to 0.843×10-3 μm2, average 0.234×10-3 μm2, belonging to low porosity and ultra-low permeability reservoir. The shale gas content in Lower Wufeng Formation-Longmaxi Formation whose thickness can reach 20 m is generally greater than 1 m3/t. The results of brittleness analysis by brittle mineral content method show that the brittleness index of shale varies from 39.6% to 89.6%, with an average of 55.4%. The brittleness index of shale at the bottom of 10 m is more than 60%, which is beneficial to the formation of complex fracture network system after reservoir fracturing. The results of brittleness analysis by elastic parameter method show that the Young′s modulus of the Wufeng Formation-Longmaxi Formation shale is mainly between 25.2 GPa and 67.5 GPa, with an average of 38.9 GPa; the Poisson′s ratio is mainly between 0.177 and 0.327, with an average of 0.297, and the brittleness index is mainly between 8.5% and 97.3%, with an average of 33.2%. The 13 m shale at the bottom has typical high Young′s modulus, low Poisson′s ratio and high brittleness index. The comprehensive evaluation results of shale brittleness indicate that the 9 m shale of the bottom of Wufeng Formation-Longmaxi Formation has the relative optimum Young′s modulus and Poisson′s ratio. Its brittleness belongs to medium and high degree. The 9 m shale has strong fracture making ability and good fracturing ability. The whole shale is divided into 4 sections of modifiable reservoir. The shale section of 2 714.4-2 723.4 m at the bottom has the characteristics of relatively minimum Poisson′s ratio, best gas content, best brittleness and high organic matter content, which constitutes the optimal reconstruction section in the study area. |
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