非常规油气富集机制与地球物理甜点识别

Sweet spot discrimination sets the key foundation for the development of unconventional oil and gas economically and effectively. Geophysical approaches play an important role in sweet spot discrimination. The uncertainty of unconventional hydrocarbon enrichment mechanism and geophysical response feature brings new challenges for sweet spot discrimination with geophysical approaches. Focusing on the scientific problems on characteristics of micro-nano pores and enrichment mechanism of unconventional oil and gas, together with the mechanics of rock physics of geophysical response of unconventional oil and gas, the refined characteristics of micro-namo pores in different lithofacies are well described with the fabric characteristics and lithofacies in details of unconventional oil and gas based on the high resolution observations and images of microscopic structure, which is helpful to elucidate the control mechanism of fabric characteristics and porous configuration working on the existent state of unconventional oil and gas. The geological evaluation criterions are developed to the classifying and grading of sweet spots of unconventional oil and gas. Furthermore, the related rock physics models are developed based on rock physics experiments to reveal the rock physics properties of the sweet spots of unconventional oil and gas. Finally, the seismic numerical modeling methods are developed to uncover the geophysical response patterns and geophysical inversion approaches are explored to fluid discrimination of unconventional oil and gas, which set the foundation for forecasting “sweet spots” of unconventional oil and gas.

甜点识别是非常规油气经济有效开发的关键，地球物理是甜点识别的主要手段。控制甜点形成的非常规油气富集机制及地球物理响应特征尚待深入探讨，给地球物理甜点识别带来新的挑战。围绕非常规油气微-纳米孔隙特征与油气富集机制、非常规油气地球物理响应的岩石物理机理两大关键科学问题，以高分辨率微观结构成像观测和岩石物理实验研究为基础，揭示非常规油气储层组构和微-纳米孔隙特征及其对油气赋存状态的控制机理，阐明非常规油气富集机制，建立非常规油气甜点分类分级地质评价体系和评价标准；构建相应的非常规油气储层岩石物理模型，明确非常规油气甜点的岩石物理特征；确立非常规油气甜点地球物理响应模式，创新非常规油气储层地球物理反演及流体检测方法，为非常规油气“甜点”识别奠定理论与方法基础。

围绕非常规油气微-纳米孔隙特征与油气富集机制、非常规油气地球物理响应的岩石物理机理两大关键科学问题，通过地质研究和物理实验，提出了非常规储层岩相划分方案，分析了我国典型海相和陆相非常规储层孔隙特征。根据高温高压甲烷等温吸附实验，建立了不同赋存状态页岩气预测方法。建立了不同评价参数与岩相储层甜点的关系模型，形成了非常规储层甜点分类分级地质评价体系和评价标准。通过三轴水力压裂实验，厘清了裂缝密度、渗透率和裂缝网复杂程度与声发射参数间的关系。通过对比非常规储层孔隙特征与构造的差异性程度，分析其对游离气富集的控制作用。实现了非常规储层三维孔隙分类和定量表征，克服了现有技术中无法对非常规储层孔隙三维结构进行分类和定量表征的问题。实现了非常规储层矿物三维空间分布识别和定量表征，解决了非常规储层矿物三维空间识别困难的问题，建立了数字岩心数值模拟方法，研究了数字岩心弹性性质的变化。建立了一套缝网扩展的声发射监测方法，获得了压裂裂缝空间展布特征。开展了非常规储层可改造性研究，利用脆性系数、应力敏感性系数，综合评价了重庆地区的可压性。构建了非常规油气储层岩石物理模型，明确非常规油气甜点的岩石物理特征，确立了非常规油气甜点地球物理响应模式，构建了针对非常规油气储层甜点的地球物理正、反演模型，综合分析非常规油气甜点地质、岩石物理、地球物理特征，创新了非常规储层参数地球物理非线性反演方法，包括强对比介质高阶近似叠前反演、各向异性参数方位叠前地震反演、物性参数叠前地震反演等，增强了反演方法在非常规储层强非均质性、强各向异性的适用性。提出了非常规储层TOC叠前地震反演预测方法，建立了非常规地层脆性叠前地震直接反演评价方法，提出了多种裂缝预测方法，如基于傅里叶级数的裂缝储层预测方法，提高了裂缝预测精度，创新了基于正交各向异性介质假设的地应力地震预测方法，形成了非常规油气地质及工程甜点识别的理论及技术体系。