Study Of Sedimentary Facies And Reservoir Geology Of The Lower Cambrian Xiaoerbulake Formation In The Keping Area

The exploration space of dolomite of Lower Cambrian Xiaoerbulake formation in Keping area is very large,but the current exploration results are few.Based on the comprehensive observation and detailed dissection of the Sugaitebulake outcrop and Shutan 1 well,using GR energy spectrum data and image data of imaging logging,this study systematically analyzed the lithofacies characteristics,facies sequence association,sedimentary characteristics,reservoir characteristics,reservoir diagenesis sequence and pore evolution history of the Xiaoerbulake formation,so as to clarify the sedimentary facies and sedimentary model of the Xiaoerbulake formation,as well as the dominant factors and distribution rules of the reservoir.The study shows that there are nine lithofacies types in the Xiaoerbulake formation,namely,muddy silt dolomite,stromatolite dolomite,algal sandstone dolomite,algal lattice dolomite,bonded granular dolomite,fine-grained(sandstone)dolomite,tuff dolomite,lamellar dolomite and muddy dolomite.The bottom is mainly muddy silt dolomite,the middle is mainly algal clastic dolomite,and the top is muddy dolomite.There are mainly six types of pore: dissolution pore,intergranular dissolution pore,intergranular dissolution pore,(algae)lattice pore,body cavity pore and structural joint.Among them,algal-clastic dolomite and fine-grained(sand-clastic)dolomite have the most developed pore,followed by stromatolite and tuff dolomite,which constitute a pore-cavity reservoir with medium-high porosity and medium-low permeability.The formation of reservoir is mainly controlled by sedimentary facies and high frequency sequence interface,and the reservoirs are mainly developed in the middle-gentle slope,hilly and beach bodies of section 1 and 2 of Xiaoshang Formation.