页岩气储层孔缝结构的多尺度探测及描述方法研究

This project aims for resolving the difficulties in exploration and development for shale gas in China. The pore-fracture distribution and the mechanisms of the complex movement of the multi-phase pore fluids in shale gas reservoirs, as well as their effects on well logging and seismic attributes, will be quantitatively studied in multiple scales from nanometer pore structures up to the resolution lengths of seismic exploration. Using the nanon and micron CT and FIB-SEM apparatus and integrating the computational rock physics methods, pore structure in the matrix and the organic matter, micro-crack density, permeability, and brittleness of a low permeability, anisotropic shale gas reservoir will be precisely delineated. Using our particular multi-frequency facilities, such as quasi-static stress-strain equipment and a sonic resonance spectrometer, we will study the broad-band multi-scale methods of integrated geophysical modeling, and will investigate the quantitative relations of key reservoir parameters to well logs and seismic attributes for shale gas reservoirs. The research results will provide critical parameters and guidelines for integrated identification of the sweet spots in shale gas reservoirs, and for reservoir characterization, horizontal drilling, and multi-stage hydraulic fracturing. This project will innovate in new exploration methodology for shale gas reservoirs suited to the geological settings in China.

本项目以解决我国页岩气勘探开发技术难题为目标，从纳米级孔隙结构到地震分辨率线度的多个尺度来研究页岩气藏的孔、缝分布及其中多相流体运移的复杂机理，定量分析它们与测井和地震属性的关系。应用纳米和微米CT及FIB-SEM设备，结合计算岩石物理方法精确刻画低孔渗、各向异性页岩气藏基质和有机质的孔隙结构、微裂缝密度、渗透率和脆性指数。应用我们独有的准静态应力-应变仪、声共振谱仪等多频段设备研究宽频带、多尺度地球物理综合建模方法，确定页岩气储层关键参数与测井、地震属性的定量关系。研究结果将为页岩气藏甜点的测井-地震综合识别，为储层描述、水平钻井和多级分段压裂开采提供关键参数和指导，为发展我国页岩气藏地球物理勘探方法开创新思路。

为解决我国页岩气勘探开发的技术难题，准确地为页岩气储层识别和压裂提供关键弹性参数，本项目旨在研究从纳米级岩石微观结构到勘探地震分辨率尺度的储层岩石孔隙结构及流体分布，分析微观非均质性对宏观的岩石物理性质和地震属性的影响。围绕该目标，我们首先优化了岩心成像资料处理过程，使处理流程更规范，参数选择更客观、更符合物理意义，图像质量更高。其次，对数字岩心建模的尺度放大问题进行了深入研究，提出了基于相似性分析的模块替代法。其在物理上更符合实际，效果优于常规的粗化法，计算效率与粗化法相当，适用于大量的岩心建模与模拟。接下来，结合多种岩心图像和矿物分析结果进行了多值化的数字岩心建模及弹性模拟。相比常规的二值化模拟，它更符合实际，结果更准确。最后，利用声波测井资料研究了地震波衰减和速度频散与总孔隙度、微裂缝密度、孔隙流体等的关系，并提供了一个半定量的模板。总体而言，本项目对数字岩石物理的理论、方法、仪器和应用技术进行了全面的调研，在数字岩心建模及弹性参数和地震波场模拟方面有较深入的研究。但是，由于数字岩石物理在国际上仍是一个新的研究领域，进一步的研究工作亟待开展。