Water flooding development has become the only way for the ultra low permeability fractured reservoir development. However, due to the problems of reservoir micro fracture development, serious heterogeneity and critical water, resulting the water flooding recovery was low.Spontaneous imbibition oil production is an important way of oil production in this kind of reservoir, on the basis of the use of indoor experiment, the salinity of injected water, core permeability, oil saturation, surfactant, oil viscosity and temperature in a low permeability fractured reservoir were studied systematically. Experimental results show that when the environment formation water salinity is less than the mainland core layer water salinity, or joining a surface active agent could significantly improve spontaneous imbibition effect. as the permeability and oil saturation increased and the crude oil viscosity decreased; capillary imbibition became stronger and the ultimate imbibition recovery is greater; the increase of temperature can increase the initial imbibition rate, but the ultimate imbibition recovery is basically the same, the temperature is not the direct acting factors about imbibition effects in ultra low permeability fractured reservoir.

Because of complexity, many aggregated methods for interval multiattribute group decision are difficult to general decision makers, a new way has been proposed in this paper. This method puts forward basic interval conception to aggregation and provides direct solution schematically. It is easier and more intuitive. Finally, as compared with the results of literature method, this has been demonstrated as an effective method.