北非Sabratah盆地下始新统El Garia组货币虫灰岩层序地层与沉积模式

北非Sabratah盆地下始新统El Garia组货币虫灰岩为Bouri油田的主力储集层,其油气产能占Bouri油田的85%左右。基于地震、钻井及测井资料的综合分析,对El Garia组货币虫灰岩沉积模式与层序地层进行了研究,结果表明:① El Garia组由1个独立的三级层序SQ1构成,为1个水进体系域和1个高位体系域的叠加;②根据SQ1内部次一级的基准面旋回及叠置关系,可将SQ1进一步划分为4个四级层序,货币虫灰岩主要发育在S1-1层序;③El Garia组沉积期表现为台地缓坡模式,由于受古隆起控制及水体深度的影响,导致货币虫生物滩多呈点状分布在古构造高部位,或呈条带状、裙边状分布在围斜坡部位,非均质性强。 

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