油藏物理学英文油藏物理学 (25).ppt

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1、4 4 Measurement of wettability1)Contact Angle methodcontact angle 0 07575water wettingwater wetting，7575 105105neutrally-wetneutrally-wet，105105180180oil-wet.oil-wet.Contact angle measurement in oil-water systems advantages of this method:Quartz is usually used to instead of sandstone,calcite instea

2、d of carbonate,this method has become a widely used method.disadvantages of this method:(1)Contact angle is measured on a flat,clean,homogeneous mineral surface.(2)Pure minerals are used in the test to simulate reservoir rocks.Pure minerals may not be representative of actual reservoir mineralogy.(3

3、)The test can be very long(4)There is evidence that the contact angle is affected by which fluid was first in contact with the solid.2)Spontaneous imbibition methodFig.3-18 spontaneous imbibition method for measurement of wettability2)Spontaneous imbibition method If the amount of water displaced by

4、 spontaneous imbibition of oil is larger than the amount of oil displaced by spontaneous imbibition of water,the rock is oil-wet.If the amount of water displaced by spontaneous imbibition of oil is equal to the amount of oil displaced by spontaneous imbibition of water,the rock is neutral wettabilit

5、y.C Characteristic of this method:Simple instrument and convenient operation.This method can reflect actual situation of reservoir.This method can only qualitatively determine wettability.3)Amott wettability index methodwater-wet index:w=vosp/votoil-wet index:o=vwsp/vwtIw=o-wAmott wettability index:

6、Determination of wettability by wettability indexTable2 Determination of wettability by wettability indexes （Hegengsheng,1994）wettability indexwettabilityoil-wetweak oil-wet neutrally-wetweak water-wetwater-wet oil-wet index10.80.70.6two index similar0.30.400.2water-wet index00.20.30.40.70.610.8Dete

7、rmination of wettability by Amott index:Table3 Determination of wettability by Amott indexAmott index-1-0.3-0.3-0.1 -0.10.1 0.10.3 0.31wettabiliy oil-wet weak oil-wetneutrally-wet weak water-wetwater-wetwettabiliy(divided roughly)oil-wetneutrally-wetneutrally-wetneutrally-wetwater-wetIw=o-w 4)Capillary pressure curve method5)relative permeability curve method6)Fluid displacement energy method