不同润湿性条件下适合于不同渗透率油层的超低界面张力驱油体系

研制了无碱无聚合物且界面张力达到10^-3mN/m超低值的表面活性剂驱油体系,对于岩石表面润湿性条件为强亲油、中亲油、弱亲油以及强亲水情况,随着渗透率的增加,该体系的采收率逐渐增加.当渗透率增加到某个值时,随着渗透率的增大采收率迅速提高;然后随着渗透率的进一步增大,采收率增加幅度明显降低,将采收率不再增加时的渗透率值称为临界渗透率值.岩石表面亲水性越强,临界渗透率越低,适合于超低界面张力驱油体系的渗透率越小.实验表明,随着岩石表面亲水性的增加,可以使残余油滴活化的最小孔喉半径或渗透率明显降低,在低渗透率、特低渗透率以及超低渗透率的条件下,可将残余油驱替出来.因此,超低界面张力驱油体系不仅适合于中、高渗透率的油层,在一定条件下还可用于低、特低和超低渗透率的油层.

Oil-displacement system with ultra-low interfacial tension for reservoirs of different permeability under different wettability on rock surface

An oil displacement system of surfactant with ultra low interfacial tension of 10^-3mN/m without alkaline and ploymer was prepared. This system is favorable for different wettability of rock. The test results identified that oil recovery increased gradually with the increment of permeability under different wettability of rock. When permeability got to a certain value, oil recovery sharply increased. Then oil recovery slowly increased or unchanged with the increment of permeability. The corresponding permeability is named as the critical permeability. The minimum pore throat radium and permeability for improving the activity of remaining oil drop decreased obviously with the increase of water wettability of rock. This means that the oil displacement system with ultra low interfacial tension is useful to enhance oil recover in low or ultra-low permeability reservoir.