Study On Technique Of Nitrogen Flooding Plugging Fissure In Reservoir Of North-two-west Western Block

According to the practical situation of Daqing Oilfield, in view of theproblem resulted by gas channeling after injecting nitrogen for the oilfielddevelopment, stability more long-lasting foamed gel plugging agent system wasdeveloped. Through researches of projects in domestic and overseas,long-lasting foamed plugging agent channeling mechanism was studied by alarge number of laboratory experiments, and four evaluation methods werecarried out for the study. Multiphase foam sealing channeling physics simulationapparatus made by our academy pioneered laboratory measurement techniquefor high-pressure gas. Long-lasting foamed gel system was selected by dozensof foaming agent screening experiments. Foaming and foam stability of thesystem were excellent, the half-life period was28.2h, and the system can adaptto all the temperature reservoir using. The system was almost unaffected by thedegree of mineralization of water, and can be used on-site sewage preparation.The results of the Physical simulation experiments showed that: the Systemresistance factor was biggest and the effect of gas-liquid mixed injection wasbetter than gas-liquid alternating injection when gas liquid ratio was2.5:1andthe flooding rate of injection was2ml/min, so the method of gas-liquidalternating injection was recommended.The starting pressure of the injection well increased and profile-log of waterinjection were effective adjustment after north2-3-66gas channeling wellsgroup injected into the system. The data of the nitrogen content in theproduction well indicated that the gas channeling of well groups has beeneffectively controlled and the long-lasting gel foam plugging reagent can plughigh permeability layer effectively and control the nitrogen gas channeling, sothe technique should be widely generalized in large area.