基于等效介质模型和频变AVO反演的裂缝储层参数估算方法

Estimation of Fractured Reservoir Parameters Based on Equivalent Media Model and Frequncy-Dependent AVO Inversion

由于裂缝性油气藏具有突出的资源潜力和经济效益,利用地震方法对裂缝储层进行精细的定量描述逐渐成为勘探地球物理的关键任务之一。为了克服以往数据驱动类反演方法无法直接获得裂缝参数、而基于静态等效介质模型驱动的反演方法无法描述孔隙内部结构和流体信息的缺点,笔者提出一种基于动态等效介质模型的储层定量描述新方法。该方法通过频变AVO(amplitude variation with offset)理论建立目标函数并使用全局最优化算法反演裂缝参数。一维和二维模型测试证实,由于充分利用了反射系数频变响应对裂缝密度和时间尺度因子的敏感性,反演方法可以对裂缝储层实现有效描述。

Because the fractured reservoirs have outstanding resource potential and economic benefits,fine quantitative characterization on fractured reservoirs using seismic methods is becoming one of the key tasks of exploration geophysics.To overcome the disadvantages of the conventional methods of data driven inversion which cannot acquire fracture parameters directly,and of the model driven inversion method based on the static equivalent medium theory which cannot characterize the internal pore structure and fluid information,we propose a quantitative reservoir characterization method based on a dynamic equivalent media model.The method establishes the objective function using frequencydependent AVO theory and uses a global optimization algorithm to estimate fracture parameters.Through applying our method to 1Dand 2D models,we can confirm that,by taking full advantage ofthe sensitivity of frequency-dependent response of the reflection coefficient to the fracture density and time scale factor,the inversion algorithm can effectively characterize the fractured reservoir.