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All schemes of location water injection wells can be used
not only for injection water but for injection gas into the oil
deposit.
Pressure maintenance by injecting gas has not found wide
use and is used mainly in depleted oil fields, where reservoir
pressure is low.
The amount of gas needed for injection into the reservoir
only for pressure maintenance at the current level will be equal to
the sum of volumes of oil, water and gas under to formation
conditions
V = V oil + V w + V g,
where V – the amount of injected gas; V oil - oil withdrawal per
day; V w - water production per day; V g – gas extraction per day.
The values V oil and V w determined by the actual data,
taking into account the volume formation factors for the oil and
water
V oil = V oil0 b oil; V w = V w0 b w,
where V oil0, V w0 – flow rate oil and water per day under standard
conditions.
V g under formation pressure and the temperature is
defined by the formula
 V  Р  Р   zTРV
V  g 0 f 0 oil 0 0 f , (4.11)
g
Р f Т 0
3
where V g0 - gas extraction per day under standard conditions, m ; α
3
3
- gas solubility coefficient m /m ·Pa; P f - formation pressure, Pa;
P 0 - pressure under standard conditions (P 0 = 0.1 MPa), Pa; z -
gas compressibility factor under formation pressure and formation
temperature; T f - formation temperature, K; T 0 - temperature
under standard conditions (T 0 = 293 K), K.
Gas injection in wells through tubing that is lowered to
the top of the filter column. Annular space between the tubing and
casing packer block, which is set at the lower end of the tubing.
The aim is to isolate the column, which does not always withstand

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