Characteristics And Genesis Of The Middle And Lower Ordovician Reservoirs In The Shunbei Area

The Tarim Basin is an important oil and gas basin in China.The former has carried out a lot of research on the Middle and Lower Ordovician carbonate reservoirs in the Tarim Basin.With the deepening of research,Sinopec Northwest Oilfield Branch has made great progress in the north of Tazhong area in recent years.In the Shunbei block,multiple wells deployed along the fault zone obtained industrial oil flow in the Middle and Lower Ordovician,and the discovery of the Lower Lower Ordovician carbonate reservoir in the Shunbei area,which is the current carbonate rock.Reservoir research provides a new direction.On the basis of previous research results,this paper starts from the core and slice observation,and starts from the Shuoguole low uplift,combined with logging and logging data to summarize the reservoirs of the Middle and Lower Ordovician reservoirs in the Shunbei area.Set rock type,reservoir space type,reservoir type,reservoir physical property and electrical characteristics;identify reservoir diagenesis under core and slice,and combine geochemical means to analyze reservoir diagenetic evolution sequence and reservoir evolution model,further Clarify the genetic mechanism of the reservoir and understand the controlling factors of the development of the Lower-Ordovician reservoirs in the Shunbei area.The reservoir types of the Lower Lower Ordovician in the Shunbei area mainly include microcrystalline limestone,bioclastic microcrystalline limestone,granular limestone and algae-bonded limestone.It mainly develops storage spaces such as dissolved pores,dissolved pores,cracks and caves.According to the genesis and the type of reservoir space,the Lower-middle Ordovician reservoirs in the Shunbei area are divided into karst-slot-cavity reservoirs and karst cave-type reservoirs.The karst cavehole reservoirs of the Lower-middle Ordovician in the Shunbei area are more developed;the karst-slot-hole reservoirs in the formation of the Yifang Formation are more developed,and the karst cave-type reservoirs in the upper section of the Yingshan Formation are more developed.The Middle-Lower Ordovician reservoirs in the Shunbei area are affected by various diagenesis processes.The dolomitization,dissolution and rupture play an important role in the study area.Through the analysis of diagenesis,the diagenetic evolution sequence in the study area is established.Due to the limited core in the north of the region,it is impossible to take enough samples for geochemical analysis.Through the core,thin-film and cathodoluminescence characteristics,based on the limited geochemical data of the Shunbei area,combined with the history of the basin's tectonic evolution,and neighboring The samples with the same characteristics in the area of Shunnan and Yuejin were analyzed by comparative geochemical analysis.It is believed that the Middle-Lower Ordovician reservoirs in the Shunbei area were affected by the Middle Caledonian hydrothermal action,the Late Caledonian-Haixi early atmospheric water karstification,and the late Hercynian Hydrothermal action,in which the early atmospheric water karstification of Haixi has the greatest impact on reservoir development,it is proposed that the early reservoir evolution model of the Haixi area in the Shunbei area is the same model as the southwestern part of the southwest,and belongs to the osmotic model along the fault.In summary,the study of the Lower and Middle Ordovician reservoirs in the Shunbei area is closely related to the fault activities and karstification.It is believed that the Lower-middle Ordovician reservoirs in the Shunbei area are formed by fracture control and multi-stage multi-type fluids.The fracture and karst development areas are favorable areas for reservoir development.