Characteristics of strike-slip faults in Xianbazha area of Tarim Basin and its petroleum geological significance
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 are Ⅰ-Ⅲ episode 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.
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