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displacement of oil by water, which states that the residual oil
saturation behind the front displacement remains constant. This is
the perfect case oil displacement when the layer between oil and
water creates a clear border section, which moves ahead of oil and
behind only water. And as shown by laboratory and industrial
researches front displacement is a compatible flow of water and
oil. Filtration resistances in the zone of oil replacement water will
differ from the filtration resistances calculated at scheme
homogeneous liquid piston displacement. Therefore, it can
consider this fact can lead to errors in determining the flow rates
and validities.
It is established that the ratio of the viscosity of oil to the
viscosity of water  0= oil/ w, which ranges from 1 to 10 in the
displacement of oil by water can be taken
m V
z  0 , (3.19)
150Q (t )

where z= o- ro ; m – coefficient of porosity; V – the volume of the
layer; Q(t) - the total amount of water that entered in the reservoir.
Equation (19) defines oil saturation at any point depending on its
position. Oil saturation at the front oil water displacement is
determined by the formula

z  1,0 0 , f. u. (3.20)
f
5 , 1   1 r o   bw  z ф
where  0= oil/ w;  r o - residual oil saturation, f.u.;  b w - saturation
of bound water, f.u.
Equation (3.20) is solved the graphic-analytical method.
For this first from the equation (3.20) is determined the value
1- r o -  b w.
To do this, the left and right sides of the equation (3.20)
to lift the square. We obtain

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