Fluidinclusionsinmineralsfilledinporesofreservoirrockscanbeusedasagoodindicatorofporegenesisanddevelopmentsoastoshedlightonoilgeneration,migrationandaccumulation.TherelationshipbetweenporeevolutionandoilgenerationhasbeenestablishedbasedonfluidinclusionstudiesontheLowerOrdoviciancarbonatereservoirstrataintheOrdosBaisn,NorthwestChina.Sevenstagesofporositydevelopmentcanberecogmized.i.e.,thepenecontemporaneous,theearlyandmiddle-latediagenetic,thesupergene,theearly,middleandlatere-buryingstages.Thedissolutionporesanfissuresformedinthesupergeneandmiddle-latereburyingstageandthestructuralfracturesformedinthelatere-buryingstageconstitutethemajortrapsofoilandgas.ThemajorphaseofoilmigrationandaccumulationtookplacebetweenLateJurassicandCretaceous,Correspondingtothemiddleandlatere-buryingstages.ThegenerationandaccumulationofoilcanbecloselyrelatedtoYenshaniantectonics.
