Nummulite Limestone Reservoir Sequence and Sedimentary Feature,Pelagian Basin

Nummulite limestone of El Garia Formation,Lower Eocene is the main reservoir of Bouri Oildfiled in Sabratah Basin,North Africa,which produces 85 % of oil in the oildfiled.This paper studies the sedimentary model and sequence stratigraphy of the Nummulite limestone based on the comprehensive analysis of seismic,drilling and well logging data.The results show that El Garia Formation is composed of one dependent SQ1 of three level sequence,the superimposition of one transgressive system tract and one highstand system tract.SQ1 can be subdivided into four 4-level sequences according to its base level cycle and superimposition,in which Nummulite limestone is developed in S1-1 sequence.Platform gentle slope model is found in the deposition process of El Garia Formation,.Because of the impact of the ancient uplift and water depth,the bioclast bank of Nummulite is usually distributed in dots in the high position of the ancient structure or in bands and apron belts along the slope margin,showing strong heterogeneity