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the saturation pressure of the oil released gas. And accordingly, the
porous medium is a two-phase filtration flow.

3.3.1 Definition of oil saturation at the end of the
interval pressure changes

Determination development indicators under the solution
gas drive is a difficult task because the drive is characterized in
descending time formation pressure and change properties
reservoir oil. To calculate development indicators (flowrates,
pressures, gas-oil ratio, oil recovery factor, time development)
must first determine the relationship between oil saturation and
pressure.
This dependence is expressed by an approximate formula
which was obtained Zinovyeva. By the method, Zinovyeva
calculations are performed in that order. Record oil saturation
formula for determining the end of interval pressure changes
P
G  S      1   P i k  P  i k 1
i k
P
b   i k i k z   PzP 
  i k 1  i k i k  i k 1 , (3.32)
G  S P  i k 1   P  i k 1
b P  i k 1  z P  i k 1 

where G - average gas-oil ratio (GOR) at the interval of change of
pressure from P kі to P k i+1 (P kі - pressure at the beginning of the
interval pressure changes; P k i+1 - the pressure at the end of the
interval changes in pressure, and P k і > P k i+1); S(P ki), S(P k i+1) - the
amount of gas that is dissolved in the oil under pressures P kі and
3
3
P k i+1, m /m ; b(P k i), b(P k i+1) – volume formation factor at the
appropriate pressures;  k I - initial oil saturation; z(P k i), z(P k i+1) –
gas compressibility factor under the appropriate pressures.
The average gas-oil ratio at the interval of change of
pressure is given by the formula

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