| 基于贝叶斯框架的各向异性页岩储层岩石物理反演技术 |
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| 引用本文： | 刘财,符伟,郭智奇,刘喜武,刘宇巍.基于贝叶斯框架的各向异性页岩储层岩石物理反演技术[J].地球物理学报,2018,61(6):2589-2600. |
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| 作者姓名： | 刘财 符伟 郭智奇 刘喜武 刘宇巍 |
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| 作者单位： | 1. 吉林大学地球探测科学与技术学院, 长春 130026;2. 页岩油气富集机理与有效开发国家重点实验室, 北京 100083;3. 中国石化页岩油气勘探开发重点实验室, 北京 100083;4. 中国石化石油勘探开发研究院, 北京 100083 |
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| 基金项目： | 国家自然科学基金重点项目（41430322），国家十三五重大专项"陆相页岩油甜点地球物理识别与预测方法"课题（2017ZX05049-002）、国家自然科学基金石油化工联合基金（U1663207）联合资助. |
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| 摘 要： | 页岩岩石物理建模旨在建立页岩矿物组分、微观结构、流体填充与岩石弹性参数的关系.对四川盆地龙马溪组页岩进行岩石物理建模研究，针对页岩黏土含量高、层间微裂缝发育等特点，利用Backus平均理论描述页岩黏土矿物弹性参数，利用Chapman理论计算与水平微裂缝有关的VTI各向异性，并利用Bond变换考虑地层倾角的影响.提出以黏土矿物纵、横波速度和孔隙纵横比为拟合参数进行岩石物理反演的方法，并引入贝叶斯框架减小反演的多解性.由已知的黏土矿物纵、横波速度和孔隙纵横比作为先验信息，并以测井纵、横波速度作为约束条件建立反演的目标函数，同时利用粒子群算法进行最优化搜索.计算结果表明，基于先验约束和粒子群算法的反演方法能够较准确地反演黏土矿物的弹性参数、孔隙形态参数以及裂缝密度等参数.计算得到的黏土纵、横波速度较高，并且在一定范围内变化，这可能与龙马溪组页岩的黏土矿物组分中具有较高弹性模量的伊利石含量较高有关，同时也与黏土定向排列等微观物性特征有关.反演得到的裂缝密度与纵波各向异性参数ε呈明显的正相关，而与横波各向异性参数γ相关性较小.另外，页岩各向异性参数与黏土垂向的纵横波速度有较强的相关性.
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| 关 键 词： | 岩石物理 黏土矿物 孔隙纵横比 贝叶斯理论 粒子群算法 |
| 收稿时间： | 2017-03-23 |
Rock physics inversion for anisotropic shale reservoirs based on Bayesian scheme |
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| LIU Cai,FU Wei,GUO ZhiQi,LIU XiWu,LIU YuWei.Rock physics inversion for anisotropic shale reservoirs based on Bayesian scheme[J].Chinese Journal of Geophysics,2018,61(6):2589-2600. |
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| Authors: | LIU Cai FU Wei GUO ZhiQi LIU XiWu LIU YuWei |
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| Institution: | 1. Geo-Exploration Science and Technology Institute, Jilin University, Changchun 130026, China;2. National Key Laboratory of Corporation of Shale Oil/Gas Enrichment Mechanism and Effective Development, SinoPEC, Beijing 100083, China;3. SinoPEC Key Laboratory of Shale Oil/Gas Exploration and Production Technology, Beijing 100083, China;4. SinoPEC Petroleum Exploration and Production Research Institute, Beijing 100083, China |
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| Abstract: | The objective of rock physics modeling for shales is to build relationships between mineralogical constituents, micro-structure, fluids and corresponding elastic properties. We conduct rock physics modeling for the Longmaxi shale formation in the Sichuan basin of China. In the model, we consider high clay content and aligned micro-cracks along beddings in the shale, and quantify the influence of elastic properties of clay by the Backus averaging theory, and apply Chapman's multi-scale fracture theory to put the pore and micro-crack system into the initial solid matrix. We use the Bond theory to calculate influence of the dipping layers. Then, we develop a rock physics inversion method, which treats elastic properties of clays and aspect ratio of pores as fitting parameters in the objective function. We employ the Bayesian scheme to reduce uncertainty of the inversion. The inversion strategy considers the prior information of P-wave velocity, S-wave velocity, and pore aspect ratio. The particle swarm optimization algorithm is employed to solve the objective function of the inversion. Inversion results show that the method based on prior constraints and particle swarm algorithm works well in predicting elastic properties of clay, aspect ratio of pores and micro-crack density. The inverted elastic parameters of clays vary with depth within a certain range and are relatively higher than the values provided by previous studies. It may result from the possibility of high content of high velocity illite in clay of the Longmaxi Formation as well as preferred orientations of clay particles. Anisotropy parameter ε has a positive correlation with crack density while anisotropy parameter γ shows a weak correlation with crack density. In addition, inverted anisotropy parameters have a close relationship with elastic properties of clay. |
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| Keywords: | Rock physics Clay Aspect ratio of pores Bayesian scheme Particle swarm optimization algorithm |
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