Enrichment Regularity And Main Controlling Factors Of Hydrocarbon Accumulation In ABU GHARADIG Basin,Egypt

A basin is located in the south of the Western Desert basin,covering a large area of 106500km~2.The oil and gas geological condition is good,developing two sets of medium-good hydrocarbon source rocks.The resource potential of oil and gas is large due to the development of effective reservoir-cap combination and the multilayer three-dimensional hydrocarbon accumulation.On the basis of geological sedimentary and tectonic studies of A basin,this dissertation analyzed the finely-discovered oil and gas reservoirs to understand the enrichment regularity and main controlling factors of hydrocarbon accumulation in A Basin and point out future exploration targets.Major findings achieved in this study are listed below:(1)A basin is a rift basin developed in Mesozoic and Cenozoic,overlying the Paleozoic residual basin.The tectonic evolution of A basin is closely related to the evolution of the African plate,including the Paleozoic craton depression stage and Cenozoic rift stage.(2)In A basin,there are two main hydrocarbon source rocks,the Jurrasic Zahara Member in Khatatba Formation and the Cretaceous ARF Member,and both are gas and oil-producing.Zahara source rocks are in mature-high maturation stage in the whole basin,and the ARF source rocks are partly mature in A basin.The discovered oil and gas reservoirs in A basin are mainly located in the shallower AR and Bahariya Formations,concentrated in the central and southeastern areas in map view.The reservoirs in the central area are mainly shallow source rock type,while the reservoirs in the southeastern areaare mainly mixed source rock type which is characterized byof the coexistence of two sets of sources rocks.(3)The Jurassic Safa Member is deposited in delta and tidal flat sedimentary environments in the transitional zone.The provenance direction is from the Northwest of the Umbarka uplift and the Qattara uplift.The sand bodies are mainly distributed in the delta front and the neighboring tidal flat along the provenance direction.The porosity of sandstone reservoir in Safa Member is about xx-xx,belonging to medium reservoir type.(4)The oil and gas are mainly located in the central and southeast parts of A basin,most of which are found in the shaollower AR and Bahariya Formations.Vertically the enrichment of oil and gas is controlled by regional and local cap rocks,while in map view the oil and gas mainly accumulate in belts,along tectonic highs and fault zones.Generally,the hydrocarbon accumulation in the study area is mainly controlled by source rocks,faults,reservoir properties of the sandstones.(5)The hydrocarbon resource in A basin is large and the exploration potential is huge,with deeper Jurassic Safa Formation and Lower Cretaceous AEB Formation being the future exploration targets.