Fluid Tracing Records Of Ultra-deep Clastic Reservoirs In Strong Tectonic Fracture Development System

The deep well area of Kuqa depression in Tarim Basin is located in western China,as an ultra-deep clastic reservoir with a depth of more than 6,000 meters.As a whole,the Bashijiqike Formation in the krasu structural belt of kuqa depression is characterized by two characteristics:one is that the reservoir physical property is relatively good and the primary intergranular pore is developed,which is especially important for the clastic strata in the deep well area of gram below 6000m;the other is that the reservoir plane physical property and vertical heterogeneity are very strong,as the ultra-deep clastic reservoir with a depth of more than 6000m.the Cretaceous reservoirs in the Keshen gas area of the Kuqa Depression are characterized by typical fracture-pore reservoirs.The development and distribution of fractures is an important factor for the improvement of reservoir performance.The development and distribution of fractures is an important factor in the improvement of reservoir performance.Previous studies have shown that fluid activity is active under the fracture system in deep reservoirs,mainly characterized by multi-scale,multi-component,multi-stage cementation filling effects,but the fluid characteristics of the fluids have not yet been clearly understood.and the constraints of tectonic movements are rarely considered while studying the tracing of diagenetic fluids in reservoirs.Therefore,the work is carried out in combination with tectonic-fluid-diagenetic work,and The prediction and distribution of deep effective reservoirs have further understanding.In this paper,the Bashkirchik Formation in the Keshen area of the Kuqa Depression is used as the research target area.Based on the study of the sedimentary and structural background.Comprehensive utilization of core observation,thin slice identification,cathodoluminescence and other research methods,combined with carbon and oxygen isotope chronology analysis and fluid inclusion temperature measurement experimental means,the analysis of the fracture filling situation and the fracture filling in the study area are used to clarify the filling degree of different well areas in Keshen area and the characteristics of filling materials.The results show:The northern Keshen well area has a large degree of structural fracture filling,and the southern filling degree is low.The fracture filling is mainly calcite filling in the north and gypsum filling in the south.The salinity of the enclosed formation water shows that the value of salinity in the south is generally higher than that in the north.The PH value in the south is greater than that in the north.The stratum water in the south is more alkaline,and the stratum water in the north is generally medium-to-alkaline.The concentration of SO₄^2-ions in formation water is high in the south and low in the north.The fracture has two characteristics of calcite filling,and there are two large-scalefluid migration activities.Both occurred in the intermediate and late stages of the Himalayan period since the Neogene.The first phase occurred about 12-7Ma,which corresponds to a rapid decline and then a slow subsidence of the formation.The second phase occurs at 5.5-3.8Ma,and the formation rapidly subsided.When the fluid entered the fractures,they were filled with cements.