超深层碎屑岩储层裂缝充填流体迁移规律——以库车坳陷克深井区白垩系巴什基奇克组为例

库车坳陷克深井区白垩系储层是埋深超过6 km的超深层碎屑岩储层，其具有典型的孔缝型储层特征。裂缝的发育与分布是储层储集性能改善的重要因素。深层储层内裂缝体系下流体活动活跃，主要表现为多尺度、多组分、多期次的胶结充填效应，但有关流体的活动特征目前尚未有清晰的认识。综合利用岩心观察、薄片鉴定，阴极发光等研究方法，结合碳、氧同位素实验分析与流体包裹体测温实验，针对研究区裂缝充填情况以及对裂缝充填物的期次分析，明确了克深地区不同井区的充填程度以及充填物的特征规律。研究结果表明：裂缝具有两期方解石充填的特点，两期大规模流体迁移活动均发生在新近纪以来的喜马拉雅运动中期。第1期发生在距今12.2~7.4 Ma，对应地层快速下降再缓慢抬升的过程；第2期发生在5.5~3.8 Ma，地层发生快速沉降，流体进入裂缝发生胶结充填效应。

Migration law of fracture filling fluid in ultra-deep clastic reservoirs: a case study of the Cretaceous Bashijiqike Formation in Keshen well block,Kuqa depression

The Cretaceous reservoirs in Keshen well block of the Kuqa depression are ultra-deep clastic reservoirs with a burial depth of more than 6 km, which have the typical characteristics of pore-fracture type reservoir. The development and distribution of fractures is an important factor for improving reservoir property. The fluid activity in the fracture system in deep reservoirs is active, mainly shown as the multi-scale, multi-component and multi-stage cemented filling effect; however, there is still not a clear understanding of the characteristics of fluid activity. Aiming at fracture filling in the study area, an analysis is performed on the stage of fracture fillings. On this basis, comprehensively using core observation, thin section identification and cathodoluminescence, in combination with the experimental analysis of carbon and oxygen isotope and the experiment of homogenization temperature of fluid inclusions, this study clarifies the filling degree in different well areas and the characteristics of fillings in the Keshen area. The results show that the fractures have the characteristics of two stages of calcite filling, and there were two stages of large-scale fluid migration activities, both of which occurred during the middle period of the Himalayan Movement since Neogene. The first stage occurred from 12.2 Ma to 7.4 Ma, corresponding to the rapid descent and later slow uplift of the formation; the second stage occurred from 5.5 Ma to 3.8 Ma, when the formation experienced rapid subsidence and the fluid entered the fracture to produce a cemented filling effect.