页岩油气层及裂缝多尺度多物理正反演

The unconventional shale oil/gas reservoirs in China are widely characterized as strong heterogeneity and anisotropy in both microcosmic and macroscopical scales, which lead to substantially complex geophysical responses in different measuring means, i.e., laboratorial, logging and seismic observations. The authentic information of the shale oil/gas reservoir is not only extensively subtle and often submerged into the reflections of non-reservoir or noise, but also difficult to be identified or connected in different measuring scales. Particularly, the sweet shale hydrocarbons especially the fractured reservoirs with different dips are hard to be precisely predicted. To solve these problems, this project is mainly designed to forward the geophysical responses of shale oil/gas reservoirs with different qualities from microcosmic core measuring to macroscopical seismic observation, and inversely construct the characterization methods for sweet reservoirs especially fractures. Based on the anisotropic rock-physics modeling and pre-stack inversion algorithms, the whole research is going to be conducted on many innovative aspects in terms of shale hydrocarbon rock-physics computing, orthotropic media forward and inverse theories, horizontal stratification fractures geophysical responses modeling and identification, frequency-dependent AVAZ inversion methods based on dynamic rock-physics, etc. The cooperative strategy that connects rock-physics and geo-physics in different scales will be proposed, which is the fundamental for the predictions of sweet shale reservoirs especially fractures. Meanwhile, a series of innovative geophysical prediction methods in different scales will be built to describe the sweet elements of shale reservoirs and the saturated fluids, which could be verified by geological, logging and seismic field data.

针对页岩油气层微观复杂性、非均匀性和宏观强地震各向异性等导致地球物理响应规律不清，不同尺度信息融合困难，甜点特别是多尺度多角度裂缝预测精度低等问题，研究基于岩石物理正反演和地球物理正反演的多物理页岩油气层甜点特别是裂缝多尺度表征方法。以各向异性岩石物理建模与地震各向异性反演方法研究为核心，在页岩油气层岩石物理计算、正交各向异性介质正反演理论与方法、水平层理缝地球物理响应规律与识别理论、基于动态岩石物理的裂缝流体频变AVAZ响应规律与反演方法等方面进行创新。提出一种岩石物理与地球物理协同多尺度融合策略，为基于岩心、测井和地震数据的甜点特别是裂缝预测奠定基础，研发页岩油气甜点要素特别是裂缝和流体的多尺度多物理预测新方法，紧密结合实际地质、测井和地震数据，检验自主创新的有效性。

针对页岩油气层微观复杂性、非均匀性、宏观强地震各向异性等导致的地球物理响应规律不清、不同尺度信息融合困难、甜点特别是多尺度多角度裂缝预测精度低等问题，研究页岩油气甜点要素地球物理响应机理与预测方法。构建页岩油气层多尺度各向异性动态岩石物理等效模型，实现测井尺度岩石物理反演，明确页岩油气层弹性及地震响应特征，遴选出甜点要素敏感弹性参数。建立一套有别于实验岩石物理、数字岩石物理的地震岩石物理计算方法，实现从储层微观结构到宏观地震尺度的岩石物理参数计算。建立一套全方位多尺度多角度叠前、叠后裂缝综合预测技术系列，实现页岩层系复杂裂缝多尺度融合预测。建立裂缝参数定量表征数学框架和反演方法，实现模型数据裂缝参数定量反演，发明一种针对实际数据的频变AVAZ属性流体识别技术，实现裂缝强度、方位和流体同时识别预测。建立一种新的弹性参数反演方法，提高密度反演精度，构建甜点预测模型，提出“裂缝”甜点概念及其评价模型，建立一套新的地层压力预测方法，甜点要素预测精度明显提高，并实现页岩油气甜点要素智能综合评价。.研究成果的创新性体现为：.（1）考虑粘土定向性、三孔隙、垂直缝、水平缝及流体动态相互作用，构建一种新的页岩多尺度正交岩各向异性复杂岩石物理模型；基于小尺度地质建模、非均匀非结构地震波场数值模拟，建立一套地震岩石物理计算方法。.（2）建立正交各向异性介质反射系数简化公式和各向异性反演方法；建立一种基于岩石物理模型的页岩水平层理密度反演方法；建立岩心、测井和叠前叠后地震多尺度融合裂缝预测方法和系统；建立HTI及TTI介质裂缝参数定量反演非线性反问题数学框架，以及遗传算法与贝叶斯概率混合参数反演方法，发明一种新的频变流体因子。.（3）提出一种新的弹性参数混合约束非线性反演方法。项目成果针对焦石坝南页岩气甜点综合评价进行应用，实现甜点要素综合评价，评价优选三类6个甜点有利目标区。