基于多尺度观测资料的地层品质因子频变规律与联合反演

The quality factor Q is closely related to the pore structure and the fluid properties, which is the important parameter in seismic reservoir prediction and fluid identification. The constant Q assumption that widely used is valid only in specific seismic frequency range, the scientific problem for the frequency-dependent rule and the joint inversion of the quality factor is focused in this project, kinds of multiscale geophysical observation data with different frequency range are used to research on the quality factor frequency-dependent rule and the joint inversion method. The theory relationship of the quality factor that changed with the frequency is built based on the multiscale rock physics theory and the pore structure characteristics, the geophysical observation methods with the ultrasonic rock physics experiment, the sonic logging, the borehole seismic, the surface reflection seismic and the low-frequency rock physics experiment method, which change from the MHz band to several Hz band, are carried out to test the quality factor from scale to scale. The simplified mathematical model is built with the frequency-dependent rule and the test data for the quality factor. Then, the physical relationship is discussed between the quality factor frequency-dependent parameters and the pore structure and the fluid characteristic. Furthermore, the object function is established for the inversion of the quality factor frequency-dependent parameters with these transcale geophysical data, the feasibility and effectiveness of the frequency-dependent parameters inversion will be discussed. This project makes full use of the advantage of different geophysical observation methods to research the frequency-dependent rule of the quality factor in more widely frequency range, which is very important for the theoretical research and the practical application to improve the precision of reservoir pore structure description and the fluid characteristic identification.

地层品质因子Q与孔隙骨架及其含流体性质密切相关，成为指导地震储层预测和流体识别的重要参数。然而，品质因子不随频率改变的假设仅在地震频带范围内成立，本项目聚焦地层品质因子频变规律与联合反演这一科学问题，充分利用多尺度观测资料综合研究品质因子随频率的变化规律。拟基于多尺度岩石物理理论与孔隙结构特征构建品质因子随频率变化的理论关系，采用岩石物理超声波实验、声波测井、井中地震、地面地震和低频岩石物理实验分别从兆赫兹到几赫兹频带范围内逐级开展地层品质因子测试与分析，建立品质因子频变数学模型，探讨品质因子频变参数与孔隙骨架和流体性质之间的物理关系。进一步采用多尺度地球物理资料建立品质因子频变参数联合反演目标泛函，探讨地层品质因子频变参数反演的可行性和有效性。本项目在更宽频带范围内联合各种观测资料的尺度优势开展品质因子频变规律研究，对提高储层孔隙结构与流体性质表征精度具有重要的理论和实际意义。

地层品质因子Q与岩石孔隙骨架及其含流体性质密切相关，在指导地震资料储层预测和油气识别中发挥着重要的作用。本项目从宽频带岩石物理实验出发，测试了孔渗特征有差异的砂岩样品在不同压力、流体类型和饱和度等条件下的弹性参数随频率变化关系，采用数字岩心方法分析了不同孔隙类型和流体性质等条件下弹性参数随频率的变化关系，从兆赫兹到几赫兹的多种尺度地球物理资料观测频带范围内探讨了地层品质因子频变规律。基于高阶广义流变学模型开展地震波在粘弹性介质中的吸收衰减特征研究，构建了粘弹性介质时间域波动方程的各种表达形式在理论上的转换关系，采用高阶广义流变学模型对地层品质因子Q随频率变化的精细特征进行数值重构，实现了针对品质因子频变规律的波动方程高精度数值模拟，精细获得了不同观测尺度下地层品质因子频变规律所引起的地震资料响应特征。在此基础上，针对地层品质因子参数Q的精确反演问题，分别从振幅谱与相位谱联合、上行波与下行波联合、旅行时与波形信息联合等三个维度建立了地层品质因子Q的联合反演方法原理，构建了不同类型的联合反演目标函数和对应的求解方法，形成了面向实际资料应用的方法技术流程，并在模型与实际资料测试中探讨了反演方法的可行性和有效性，结果表明充分利用地震资料中的不同信息开展联合反演能够更好地提高地层品质因子参数的反演精度。本项目围绕地层品质因子Q开展了多尺度频变规律分析测试、频变特征的模型表征、精细波场模拟、联合反演方法等研究，对促进地层品质因子在油气储层预测中的应用具有重要的理论和实际意义。