Reservoir Heterogeneity Features And Influencing Factors Analysis Of The Tsagantsav Ⅱ Formation Of The South Sag Of Tamsag In The Tamsag Basin

The Tamsag Basin and the Hailaer basin are belong to the same Mesozoic sedimentary basin. The South sag of Tamsag locates in the south of Tamsag depression basin in the Tamsag Basin. In the sag, sedimentary structures are rich, sedimentary facies change quickly. Marked characteristics of the sag are that it has much more material sources and sedimentary centers. At the same time, the rift system of the region is very complex, faults are development, the change of stratum thickness is big. At the seismic cross-section, we can see the phenomenon of unconformity, die out and dislocation of layers in much region. The mainly petrophysical characteristics of the reservoir are of low permeability and low porosity and the porosity were so poor. These characteristics have caused that the heterogeneity in the South sag of Tamsag is outstanding. So the research of reservoir heterogeneity is of great significance.The mainly study content arereservoir heterogeneity characteristics and influencing factors of the TsagantsavⅡFormation of the South sag of Tamsag in the Tamsag Basin. After checking out the geological data, the paper research microscopic reservoir heterogeneity, in layer heterogeneity and surface heterogeneity characteristics, according to the physical property data,geology data, well log information, log data, seismologic data and other aspects data ,and collecting and analysing thin slices,SEM,images,mercury penetration information. Next step is analyzing qualitativly influencing factors of reservoir heterogeneity features, establishing the relationship with structure, sedimentary and reservoir heterogeneity in combination with regional tectonic study and the research of sedimentary facies.Through the analysis, madding the following related ideas:1. TsagantsavzuⅡin the microscopic reservoir heterogeneity group, its lithology and physical property all represent heterogeneity features. We can see heterogeneity features in layers too, according to poroperm characteristics and petrography character.2. TsagantsavzuⅡrepresent sharp heterogeneity features in stratum thickness, sand body thickness, and the ratio of sand body thickness with stratum thickness'horizontal change, even in the single fault block whose area is very small.3. From the beginning of fault subsidence period, hanging wall formed subsidence center, because the basin was in the role of tension stress, which control the sedimentary distribution of Tsagantsav formation. Stuck faults'activity is the most direct control function of the reservoir heterogeneity in the sedimentary periods. In the late time, faults'continue activity played a microscopic transformation role for Tsagantsav formation. So Structural factors is the most direct control factors of reservoir heterogeneity, sedimentary and diagenetic factors also are the important factors.4. Sedimentary microfacies characteristics of Tsagantsav formation are near the provenance and have many provenances. In the northeast, the west, the southwest, southeast of the basin all have source supply and sedimentary microfacies in the transverse conversion change frequently. Fan delta system development various microfacies. The sedimentary facies control the characteristics of sand body development.