Research On Formation And Damage Of Mesozoic And Paleozoic Reservoir In Yihezhuang Area,Jiyang Depression

The Yihezhuang uplift area of the Jiyang Depression,which is located between Chezhen Sag and Zhanhua Sag,has very favorable hydrocarbon sources.The Mesozoic and Paleozoic have enormous potential for oil and gas exploration.However,there are only a few researches on the Mesozoic and Paleozoic.The hydrocarbon sources are very complex.The reservoirs have ever experienced drastic destruction.The migration and accumulation of hydrocarbon and the genetic mechanism of heavy oil in the Mesozoic and Paleozoic are not yet clear.Therefore,it is very critical for the hydrocarbon exploration strategy that determine the process of formation and damage of the Mesozoic and Paleozoic reservoir.A series of experimental analysis were performed on crude oil samples and rock samples,including total hydrocarbon chromatography,mass spectrometry,high resolution mass spectrometry.The geochemical characteristics of crude oil and the migration and accumulation process of hydrocarbon in the Mesozoic and Paleozoic are revealed by the comprehensive research on these experimental results.The crude oil of the Mesozoic and Paleozoic in the study area came mainly from the Sha 3 Member and the Sha 4 Member in the Sikou Sag,as well as from the Sha 1 Member.The Mesozoic and Paleozoic experienced two significant accumulation events respectively in the deposition of the Guangtao Formation and the Minghuazhen Formation,especialy in the latter.The oil and gas migrated from the Sikou depression into reservoir mainly through the Yidong fault zone,unconformity and transport layers.And the overall migration trend is northwest direction.Atmospheric fresh water,which infiltrated in the Palaeo-oil reservoir through the faults and unconformity,caused crude oil to suffer from biodegradation,oxidation,water washing and final thickening.