Description Of The Characteristics Of The Ordovician Fracture Caverns In The Second District Of Tahe

In this article,We use the relative knowledge of the reservoir geology,carbonate sediments,logging and developing geology and study a large number of previous studied to research the Ordovician carbonate rock karst reservoirs in the Tahe.And use the core observation description,logging reservoir identification and seismic attribute prediction to summarize the types of reservoirs and reservoir genesis of the Ordovician septum in Tahe.Discuss the reservoir development regularity and reservoir control factors and evaluate favorable reservoirs.There are four main reservoirs grow in the Ordovician reservoirs of the Tahe second district:fractured-porosity reservoirs,fractured-hole reservoirs,cave-type and fractured reservoirs.Combined with production dynamics data,it indicates to the karst cave reservoirs that contributes the largest and most important;the contribution of fractured-hole reservoirs is also large and important;the contribution of dissolution pore-type reservoirs and fractured reservoirs is very limited.The development of karst reservoirs is controlled by the tectonic activity of the Caledonian and the Hercynian tectonics.The distribution of the karst reservoirs is closely related to the early Hercynian unconformity.In the depth range of 0?40m below the early Hercynian unconformity,the frequency of karst reservoirs is 91.7%,and the frequency is significantly reduced down below that range.It shows that the area near the northern part of the Tahe Oilfield and the pinch-out boundary,the depth range of 0?40m,is the karst reservoir(karst cave reservoir and karst seam hole reservoir stack together)general development section.In a certain sense,the reservoir can be considered by the characteristics of a layer distribution(or block spread)of the unconformity surface.The early karst in the Haixi area is generally developed in the north of the Ordovician Qaerbak Formation in the Ordovician reservoir of the Tahe District 2,and at the same time,the synovial atmospheric water dissolution is in the southern cover area.The main controlling factors of reservoir development and distribution are the characteristics of fault distribution,palaeo-topography and paleo-water system.The seismic response of Ordovician reservoir in Tahe District ? is mainly characterized by "weak surface "And" surface strong(weak)+insider clutter reflection".Finally,on the basis of the above research,according to the above knowledge,we believe that the potential zone of the second section is mainly in the near north-south stripe of TK252-TK233X;near northwest-southeast tectonic slope of TK209-TK212;near northeast-southwest tectonic slope of S79-T208.The eastern well area of TK242-TK254 has low drilling density,which partly has the characteristics of weak and insider strong amplitude,and can further evaluate the potential.