地震属性与地质力学联合的裂缝建模技术及裂缝有效性分析——以四川盆地涪陵地区侏罗系页岩为例

    Seismic attribute-geomechanics integrated fracture modeling technology and fracture effectiveness analysis: A case study of the Jurassic shales in the Fuling area, Sichuan Basin

    • 摘要: 断裂分布影响页岩气水平井的轨迹设计和压裂人工裂缝的改造效果。断层和节理是断裂的两种类型,通过地震属性实现断层建模,利用地质力学构造恢复和摩尔库伦理论实现节理缝预测;离散网格裂缝(DFN)在建模时融合断层建模和节理缝建模结果,实现天然构造裂缝的空间刻画。将该方法应用到四川盆地涪陵地区侏罗系陆相页岩勘探中,裂缝模型与成像测井解释结果一致,明确了裂缝发育区和裂缝空间的展布规律;通过典型井裂缝建模与压裂效果对比进行压裂改造有效性评价,提出拉张性质的垂直或斜交井轨迹方向的裂缝更有易于压裂改造。此项成果对勘探阶段预测裂缝发育区和指导水平井轨迹设计有积极意义,能为下一步勘探部署提供指导。

       

      Abstract: The distribution of fractures influences the trajectory design of shale gas horizontal wells and the stimulation effectiveness of hydraulic fractures. Faults and joints serve as two types of fractures. Accordingly, this study proposed the seismic attribute-geomechanics integrated fracture modeling technology. Specifically, fault modeling is conducted using seismic attributes, and joint prediction is performed using geomechanical structural restoration and Mohr-Coulomb theory. The obtained results of faults and joints are then integrated into the discrete fracture network (DFN) modeling for spatial characterization of natural tectonic fractures. The proposed technology was applied to the exploration of Jurassic lacustrine shales in the Fuling area within the Sichuan Basin. Its fracture modeling results were consistent with the imaging log interpretation results, confirming the development zones and spatial distribution patterns of fractures. Moreover, the stimulation effectiveness of fracturing was evaluated by comparing the fracture modeling results of typical wells with the actual fracturing performance. The evaluation results indicate that tensile fractures that are vertical or oblique to well trajectories are favorable for fracturing. Overall, the results of this study hold positive implications for predicting fracture development zones and guiding horizontal well trajectory design in the exploration stage, serving as a reference for subsequent exploration deployment.

       

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