Study On Sedimentary Characteristics And Favorable Sandbody Prediction Of Shahejie Formation Of Paleogene In Qingdong Depression

Guided by seismic stratigraphy and sedimentology, based on building up seismic strata framework and using data of seismism, core, mud logging and log, the author divide Member 3 of Shahejie Formation into three 4th seismic subsequences, which correspond to the upper, middle and lower parts of Member 3 of Shahejie Formation.By means of core data, grainsize analysis, thin section identification and analysis of seismicfacies and electrofacies, combining with the correlations of single well facies and profile facies, the systemic studies of sedimentary characterization, spacial spreads of sand bodies and controlling factors of Member 4and Member 3 of Shahejie Formation of Qingdong Depression are done. The result indicates that fan delta, deep lake and sublacstrine fan are developed in Qingdong Depression during the period of depositon of Member 4 of Shahejie Formation. During the period of depositon of Member 3 of Shahejie Formation, fluvial and delta are develop in southern Qingdong Depression. Meanwhile, fan delta and sublacstrine fan are developed in the norhern Qingdong Depression.Studying on seismism data , percentage of sandstone and lithological feature, the author think that Weibei arch is southern source of Shahejie Formation, where two fans near Qingdong 4 well and laixie 62 well are developed. Meanwhile, the author think Qingtuozi arch is northern source, where two fans near Lai102 well and Qingdong 5 well are developed.Primary pore and secondary pore are developed in Shahejie Formation of Qingdong depression. Secondary pore dominates Memer 4 and Member 3 of Shahejie Formation of the northern study area. Primary pore, mixed pore and secondary pore are developed in Member 3 of Shahejie Formation of the sourthern study area. Primary pore, dissolution intergranuler pore, constricted fracture and dissolution fracture are main reservoir space.In general, the sand bodies of debouch bar depositon of Member 3 and Member 4 of Shahejie Formation of Qingdong Depression are developed. And they are favorable sandbody of reservoir.