柴北缘马海古隆起形成机制数值模拟分析

Mahai Paleodoming Formation Mechanism Numerical Simulation Analysis in North Margin of Qaidam Basin

柴北缘马海古隆位于柴北缘西段中部,由于受多期构造运动的影响,构造极为发育,油气勘探难度大。以构造地质学、石油地质学、层序地层学等理论为指导,利用下伏地层的削截和上覆地层层序的超覆、尖灭、地层的缺失等标志来识别古隆起,分析认为马海古隆起的形成是印支运动所引起的古特提斯洋关闭与基底岩性及刚度差异联合作用所致;利用美国Itasca公司开发的基于拉格朗日元法的有限差分程序FLAC3D,建立岩性均匀的莫尔-库仑弹塑性介质模型,从定性的角度模拟验证马海古隆起形成所受的构造应力的方位。

The Mahai paleodoming is situated in the middle part of west sector, north margin of the Qaidam Basin. Since impacted by multi-stage tectonic movements, thus, structures are well developed and bring on oil and gas exploration very difficult. Guiding under structural geology, petroleum geology and sequence geology theories, using marks of underlying strata truncation, overlying strata overlap, thin out and hiatus identify paleodomings. The analysis has considered that the formation of Mahai paleodoming is from combined actions of Paleotethys closing, basement lithologic and rigidity differences brought by the Indosinian movement. Using the finite difference software FLAC3D developed by the American Itasca company based on Lagrangian element method, modeled Mohr- Coulomb elastoplastic medium model, to simulate and validate the orientation of tectonic stress subjected to the formation of Maihai paleodomin~ from qualitative point of view.