基于差异充填的致密砂岩裂缝多期演化及量化表征

The conventional mechanical models and modeling methods are no longer applicable for prediction accuracy of complex fracture systems in tight sandstone reservoir, which commonly had experienced multiphase development and filling process, and cannot meet the demands of exploration and development. It is necessary to set up reasonable representation model for fracture parameters. Field observation,core observation and thin section observation will be carried out to analyze the characteristics of fracture networks, and combined with tectonic evolution history, fluid-inclusion tests and carbon -oxygen isotopes tests, to divide fluid migraction issues and fracture development times. Then hydrothermal corrosion-precipitation simulation experiment and rock mechanical experiment will be conducted to reveal the mechanism of fractures infill and dynamic process of fractures from initiation to extension and superposition. Experimental statistical method and mathematical derivation method will be used to establish the anisotropic failure criterion and constitutive relationship in view of different filling rules, then to deduce numeral superposition algorithm to set up quantitative characterization expressions between fractures based on on the principle of energy conservation and theory of strain energy density. Finally, an overall geological model including fracture and host rock is builded, which combining quantitative multi-filed coupling numerical simulation to verify reliability of the models. As a result, a set of theory and method can be provided for quantitative prediction of tight sandstone reservoirs, and be served for exploration and development of unconventional gas field.

复杂裂缝系统的多期发育和差异充填特征，直接影响着致密砂岩储层裂缝预测的精度，常规力学模型和建模方法无法满足目前勘探开发的需要。拟通过野外考察和CT扫描，分析裂缝发育特征，结合构造演化和现代分析测试手段，确定裂缝充填和发育期次；通过热液充填模拟实验和岩石力学实验，揭示裂缝溶蚀-充填机理及分布规律，及在多期应力作用下裂缝的萌生、扩展和叠加机制；采用实验统计和数学推导方法，基于能量守恒定律和应变能密度理论，建立裂缝性岩体各向异性复合破裂准则，推导多期裂缝参数叠加算法，建立差异充填规律约束下的裂缝表征模型；基于裂缝与母岩耦合模型，采用多物理场数值模拟平台，验证力学模型的可靠性。最终，完善致密砂岩多期裂缝演化及量化表征的理论体系，为此类油气田的勘探开发提供重要科学依据。

复杂裂缝系统的多期发育和差异充填特征，直接影响着致密砂岩储层裂缝预测的精度，常规力学模型和建模方法无法满足目前勘探开发的需要。拟通过野外考察和CT扫描，分析裂缝发育特征，结合构造演化和现代分析测试手段，确定裂缝充填和发育期次；通过热液充填模拟实验和岩石力学实验，揭示裂缝溶蚀-充填机理及分布规律，及在多期应力作用下裂缝的萌生、扩展和叠加机制；采用实验统计和数学推导方法，基于能量守恒定律和应变能密度理论，建立裂缝性岩体各向异性复合破裂准则，推导多期裂缝参数叠加算法，建立差异充填规律约束下的裂缝表征模型；基于裂缝与母岩耦合模型，采用多物理场数值模拟平台，验证力学模型的可靠性。最终，完善致密砂岩多期裂缝演化及量化表征的理论体系，为此类油气田的勘探开发提供重要科学依据。