| 矿物组分对龙马溪组页岩动、静态弹性特征的影响 |
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| 引用本文： | 王斌,邓继新,刘喜武,潘建国,王佳庆,肖顺垚.矿物组分对龙马溪组页岩动、静态弹性特征的影响[J].地球物理学报,2019,62(12):4833-4845. |
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| 作者姓名： | 王斌 邓继新 刘喜武 潘建国 王佳庆 肖顺垚 |
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| 作者单位： | 油气藏地质及开发工程国家重点实验室(成都理工大学),成都610059;中石油勘探开发研究院西北分院西部勘探所,兰州 730020;油气藏地质及开发工程国家重点实验室(成都理工大学),成都610059;成都理工大学地球物理学院地球物理系,成都610059;中石化石油勘探开发研究院油气地球物理研究中心,北京,100728;中石油勘探开发研究院西北分院西部勘探所,兰州,730020;成都理工大学地球物理学院地球物理系,成都,610059 |
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| 基金项目： | 国家自然科学基金项目（41774136，41374135，U1663207）和国家重点基础研究发展计划（973计划）课题（2014CB239104）资助. |
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| 摘 要： | 龙马溪组页岩是目前国内页岩气勘探的主要层位之一,其静态弹性性质是影响压裂效果的重要因素,而动态弹性性质则是页岩"甜点"地震预测的重要基础.但对龙马溪组页岩动、静态弹性特征相互关系及其影响因素缺少对比研究,致使运用动态弹性性质进行"甜点"预测时存在不确定性.在对龙马溪组页岩样品系统动、静态性质联合测量基础上,分析了页岩样品动、静态弹性性质的变化规律,并讨论了成岩作用与动、静态弹性性质变化规律的因果关系.研究结果表明,龙马溪组页岩上下两段成岩过程存在明显差异,致使上段页岩在结构上表现为以塑性黏土颗粒作为受力骨架,而下段页岩在结构上逐渐转变为脆性石英颗粒作为受力骨架.页岩岩石结构特征的变化控制了动、静态弹性特征的整体变化规律,表现为动、静态杨氏模量、峰值强度等随石英含量的增大表现出近似"V"型的变化形式,而与钙质含量变化呈现正相关关系,与黏土含量变化表现出负相关性.上段页岩宏观力学性质受微观石英+黏土颗粒集合体弹性性质控制,应力应变曲线表现出明显塑性段,动、静态杨氏模量比大于1.4,破裂易于发生在黏土与石英颗粒边界形成宏观单剪型破裂模式,样品脆性低,且脆性变化不受石英含量的影响.下段页岩宏观力学性质受微观石英颗粒集合体弹性性质控制,应力应变曲线表现为弹性变形,动、静态杨氏模量比小于1.4,破裂发生在石英颗粒内部形成宏观劈裂型破裂模式,样品脆性高,且脆性变化与石英含量呈明显正相关关系.研究结果可为龙马溪页气储层的测井解释和地震"甜点"预测提供依据.
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| 关 键 词： | 龙马溪组页岩 动态弹性性质 静态弹性性质 脆性 |
| 收稿时间： | 2019-04-20 |
The influence of rock composition on dynamic and static elastic properties of Longmaxi Formation shales |
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| WANG Bin,DENG JiXin,LIU XiWu,PAN JianGuo,WANG JiaQing,XIAO ShunYao.The influence of rock composition on dynamic and static elastic properties of Longmaxi Formation shales[J].Chinese Journal of Geophysics,2019,62(12):4833-4845. |
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| Authors: | WANG Bin DENG JiXin LIU XiWu PAN JianGuo WANG JiaQing XIAO ShunYao |
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| Institution: | 1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China;2. Oil and Gas Geophysics Center, Sinopec Petroleum Exploration and Production Research Institute, Beijing 100728, China;3. Department of Geophysics, College of Geophysics, Chengdu University of Technology, Chengdu 610059, China;4. Petrochina Research Institute of Petroleum Exploration & Development, Lanzhou 730020, China |
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| Abstract: | Longmaxi Formation shale is the prior horizon for shale gas exploration in China. Its static elastic properties are essential to the formation's response to hydraulic fracture stimulation, and its dynamic elastic properties are the important basis for "sweet spot" prediction by seismic method. While comparative studies about the dynamic and static elastic properties and its influence factors are actually insufficient, the resultant seismic method for "sweet spot" prediction is less certain. In this paper, dynamic and static elastic properties for the shale gas samples from Longmaxi Formation are discussed based on acoustic experiments and triaxial test. The influence of diagenetic evolution on these dynamic and static elastic properties is also discussed. The results show that the ductile clay minerals are the major load-bearing grains for the rock texture of the upper part of Longmaxi Formation shale, and brittle quartz minerals gradually replace clay as the load-bearing grains for the rock texture of the lower part of Longmaxi Formation shale. The rock texture variations control the overall regularities of dynamic and static elastic properties. The relationship between dynamic and static Yong's modulus and peak strength and the quartz content is more complex, and V-shape variation can be observed. A positive correlation between carbonate content and dynamic and static Yong's modulus and peak strength is also observed, and a negative relationship exists for clay content. For upper part of Longmaxi Formation shale, the macroscopic geomechanical properties is controlled by the elastic properties of the quartz+clay aggregates at microscope, which results in an apparent plastic strain in the stress-strain curves, higher dynamic modulus to static modulus ratio, single shear and double shear failure modes with rupture between quartz and clay boundary, low brittleness, and quartz content has little or no effect on brittleness. For lower part of Longmaxi Formation shale, the macroscopic geomechanical properties is controlled by the elastic properties of the cluster of micro-quartz, which results in an apparent elastic strain in the stress-strain curves, lower dynamic modulus to static modulus ratio, splitting failure modes with rupture within quartz grains, high brittleness, and quartz content is positively correlated with brittleness. Our results can provide a basis for well-logging interpretation and "sweet spot" discrimination using seismic method for Longmaxi Formation shale. |
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| Keywords: | Longmaxi Formation shales Dynamic elastic properties Static elastic properties Brittleness |
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