库车坳陷构造挤压对流体动力的影响

库车坳陷喜马拉雅晚期构造挤压强烈,流体动力分布复杂。为分析库车坳陷构造挤压对流体动力的影响,模拟了库车坳陷喜马拉雅晚期最大主压应力的分布;利用建立的构造挤压增压模型,评价了库车坳陷主要构造带喜马拉雅期构造挤压增压;将沉积型超压和构造挤压增压加以叠合,获得了库车坳陷目的层的压力演化历史,并恢复出气势的演化历史;在构造应力场和流体动力恢复的基础上,分析了库车坳陷构造挤压对流体动力的影响及天然气运聚特征。结果表明,库车坳陷在构造强烈活动期,构造挤压改变了流体动力的大小,流体动力的增大增强了天然气的运移动力,有利于天然气运移,流体动力的减小减弱了天然气的运移动力,有利于天然气聚集;构造挤压也改变了流体动力的方向,构造挤压作用下,使局部圈闭成为相对低势区,成为天然气运移的指向区;较强流体动力指向上的弱流体动力区,可成为天然气的有利聚集区。

Effects of tectonic compression on hydrodynamic force in Kuqa Depression

Late Himalayan tectonic compression was strong in Kuqa Depression,Tarim Basin,resulting in complex hydrodynamic force distribution.In order to understand the effects of tectonic compression on hydrodynamic force in Kuqa Depression,we simulated the distribution of the maximum principal compressive stress of Kuqa Depression in the Late Himalayan period.The tectonic compression model was used to evaluate the amplitude of tectonic overpressure in the main tectonic zones of Kuqa Depression in the Late Himalayan period.The evolution history of fluid pressure in the major target formations of Kuqa Depression was defined and that of gas pressure potential was restored by integrating the depositional overpressure with the tectonic compressive overpressure.Based on restoration of tectonic stress field and paleohydrodynamic force,we analyzed the effects of tectonic compression on hydrodynamic force and the characteristics of gas migration and accumulation in Kuqa Depression.Tectonic compression can change the hydrodynamic force in Kuqa Depression during strong tectonic activity.The enhancement of hydrodynamic force can increase gas migration force,being favorable for gas migration.The lowe-ring of hydrodynamic force can reduce gas migration force,being favorable for gas accumulation.Tectonic compression also can change the direction of hydrodynamic force,turning the local traps into relatively low potential areas,to which gas migrate.Areas with weak hydrodynamic force in the direction of stronger hydrodynamic force are favorable for hydrocarbon accumulation.