25. Give the Russian equivalents to the English ones.

relative adhesion	scattered areas throughout the rock
two or more immiscible fluids	have an equal preference for water or oil
water–wet brine-oil-rock system	interfacially active polar organic compounds
a film of water	profound influence
area of high oil saturation	chemical constituents in the fluids
exhibit neutral wettability	native-state wetting properties

26. Read the sentences and decide whether they are True (t) or False (f). If False (f), correct the statements.

1. In water–wet brine-oil-rock system, water will occupy the larger pores and wet the major portion of the surfaces in the smaller pores.

2. Water will saturate the smaller pores, displacing oil from the core when the system is in contact with water.

3. The wettability of a system can range from strongly water-wet to strongly oil-water depending on the brine-oil interactions with the rock surface.

4. The residual oil saturation of fractional-wettability rocks is usually low.

5. The water film between the rock and the oil in the pore isn’t stabilized by a double layer of magmatic forces.

6. Compounds displace the remaining water and react directly with the oil surface when the electrostatic force balance is destroyed.

27. Answer the following questions and find the proof in the text.

1. What term is used to describe the relative adhesion of two fluids to a solid surface?

2. In what system, will water occupy the smaller pores and wet the major portion of the surfaces in the larger pores?

3. A core saturated with water is oil-wet if it will imbibe oil, isn’t it?

4. When does fractional wettability occur?

5. What is neutral wettability used to imply?

6. What does the term “mixed wettability” commonly refer to?

7. Where is oil located?

8. Does oil displacement from the core occur at low oil saturation?

9. Does wettability have a profound influence on all types of fluid-rock interactions?

10. What factors affect the wettability?

11. Why does wettability present a serious problem for core analyses?

28. Complete the sentences using the terms of the text.

1. ________ is a measure of the preferential tendency of one of the fluids to ________ (spread or adhere) the surface.

2. ________ wettability implies ________ ________ wetting of the surface, labeled “Dalmatian wetting”.

3. ________ wettability occurs when the surfaces of the rocks are composed of many minerals.

4. ________ wettability can occur when oil containing interfacially active polar organic compounds ________ a water-wet rock saturated with ________.

5. The water film between the rock and the oil in the pore is stabilized by a double layer of ________ ________ .

6. If the rock surface is ________ water-wet and the rock is saturated with oil, water will ________ into the smaller pores, ________ oil from the core when the system is in contact with water.

7. The film ________ , allowing the polar organic compounds to displace the remaining water and react directly with the rock surface.

8. Wettability presents a serious problem for ________ analyses.