准噶尔盆地南缘红雁池断裂带结构特征及流体运移模式

Fault Zone Structure and Fluid Flow Model of the Hongyanchi Fault in Southern Junggar Basin

为探讨断裂带流体运移的相关问题,以准噶尔盆地南缘红雁池断层为例,揭示了一个以岩石变形机制与流体成岩胶结为控制因素的断裂带流体运移模式。露头调查表明红雁池断裂带发育多个结构带,各结构带破裂及充填特征等显著不同;渗透性分析表明,破裂机制差异与胶结程度的强弱共同导致断裂带渗透性的非均质特征;流体运移的岩矿学记录证实,断裂带流体运移受控于破裂机制和流体成岩的相互作用。综合研究表明,断裂带流体运移首先受控于破裂机制,新形成的高渗透性脆性裂缝带是流体运移优势路径,绝大部分流体通过优势路径来运移;其次是成岩胶结,丰富的流体活动导致断裂带强烈的成岩胶结,渗透率迅速减低直至封堵,流体运移结束。

The fault zone controls many geological processes including hydrocarbon migration. Factors controlling fluids flow in fault zone are still not well understood. A new mode was proposed for fluid flow in fault zone by taking the Hongyanchi Fault in southern Junggar Basin as an example. Field investigation shows that several sub-structural zones with different rupture and filling characteristics are developed in the fault zone. Permeability analysis indicates that both rupture mechanism and cementation degree result in permeability heterogeneity of sub-structural zones. Combined with the rock mineralogical record of fluid flow,fluid migration in the fault zone is proposed to be controlled by the interaction between rupture and fluids. The fluid migration model is as follows: firstly,fluid flow in fault zone is first controlled by the rupture mechanism,the newly formed brittle fracture with higher permeability are preferred path for most fluids;secondly,diagenesis is another controlling factor,which leads to strong cementation and rapid decrease of permeability in brittle fracture zone;finally,fluid flow ceases. The model can explain well the path selection,duration and intensity of fluid flow in fault zone formed during uplifting.