塔里木盆地先巴扎地区走滑断裂特征及石油地质意义

Characteristics of strike-slip faults in Xianbazha area of Tarim Basin and its petroleum geological significance

文中利用三维地震资料开展了麦盖提斜坡先巴扎地区断裂的精细解析,明确了走滑断裂特征、形成期次、成因机制等,结合邻区含油气地质条件,探讨了奥陶系走滑断裂的含油气性,预测油气富集模式。研究发现,研究区发育北东向、北西向、近南北向、北东东向等4组走滑断裂体系,主要经历了5期构造活动,形成了5个构造层:加里东早期发育北东向、北西向正断裂(基底构造层);加里东中晚期受西昆仑造山运动影响,部分正断裂继承活动,形成左行左阶北东向、右行左阶北西向走滑断裂(下构造层);加里东晚期—海西早期受阿尔金造山运动影响,形成1条左行左阶北东东向走滑断裂(中构造层);海西晚期北东向、北西向走滑断裂继承活动,同时新形成色力布亚逆冲断裂的近南北向伴生断裂(上构造层);喜山早期沿古近系膏泥层发育叠瓦状逆冲断裂及在喜山晚期发生整体掀斜(顶构造层)。基于邻区含油气特征,认为该区沿断裂带发育加里东中期Ⅰ—Ⅲ幕岩溶缝洞型储层,与上覆志留系泥岩形成储盖组合,海西晚期来自麦盖提斜坡西北部寒武系玉尔吐斯组的远源油气沿先巴扎断裂带向走滑断裂调整聚集成藏。其中,断穿基底的奥陶系北东向张扭走滑断裂的储集性能优于其他走向断裂,含油气条件最优越,值得探索。

This article uses three-dimensional seismic data to carry out detailed analysis of faults in the Xianbaza area of the Maigaiti slope,clarifies the characteristics,formation periods,and genetic mechanisms of strike-slip faults.Combined with the oil and gas geological conditions of neighboring areas,the oil-gas bearing properties of Ordovician strike-slip faults are discussed,and oil and gas enrichment patterns are predicted.The research shows that,four sets of strike-slip fault systems are developed in the research area,namely NE,northeast,nearly NW,and NEE trending systems.The research area mainly experienced five periods of tectonic movements,forming five structural layers:in the early Caledonian period,NE and NW trending normal faults were developed(basement structural layer).Due to the influence of the West Kunlun orogeny in the mid to late Caledonian period,some normal faults inherited the activities and formed left lateral left en echelon NE trending and right lateral left en echelon NW trending strike-slip faults(lower structural layer).During the late Caledonian to early Hercynian period,a left lateral left en echelon NEE trending strike-slip fault(middle structural layer)was formed due to the influence of the Altyn orogeny.In the late Hercynian period,the NE and NW trending strike-slip faults inherited the activity,and at the same time,a nearly north-south trending associated fault(upper structural layer)of the Selibuya thrust fault was newly formed.In the early Himalayan period,there were stacked-tile-shaped thrust faults developing along the Paleogene gypsum mud layers,and in the late Himalayan period,the overall tilting(top structural layer)occurred.Based on the oil-gas bearing properties in neighboring areas,it is believed that there areⅠ—Ⅲepisode karst fractured-vuggy reservoirs developing in the middle Caledonian period along the fault zone,forming a reservoir-cap combination with the overlying Silurian mudstone.In the late Hercynian period,far-source oil and gas from the Cambrian Yuertus in the northwest of the Maigaiti slope were adjusted and accumulated along the Xianbazha fault towards the strike-slip fault.Among them,the Ordovician reservoir performance of the northeast trending transtensional strike-slip fault that breaks through the basement is superior to other trending faults,and its oil and gas conditions are the most favorable,which is worth exploring.