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Q  e  u
P   Ptr,    du,
f
4 kh u 2 u
r
where u  , E i - exponential function.
2 t 
After mathematical transformations, we obtain the basic
formula of elastic drive
Q , 2 25 t
P   Ptr ,  f  4 kh ln r 2 , (3.27)

where P(r, t) - pressure at a distance r in time t, Pa; P f – formation
3
pressure, Pa; Q – performance (or flowrate), m /s; μ – dynamic
viscosity of the fluid, Pa·s; k – permeability coefficient of the
2
reservoir rock, m ; h – layer thickness, m; χ – piezoconductivity
2
factor, m /s.
Piezoconductivity factor characterises the rate of
transmission of pressure in the formation and determines by the
formula
k
  , (3.27)
 *
2
it varies from 0.1 to 5.0 m /s.
Bottom-hole pressure is determined by the formula
Q , 2 25 t
 ,trP  P  ln , (3.28)
f
w
4 kh r rw 2
where r wr – reduce radius, m. Reduce radius - is a radius, which
should be well, so that it was perfect.
Formula (3.27) in the oilfield practices used to assess
pressure changes over time, depending on the selection in the
initial stage of development of oil when the deposit on a small
number of wells. It is assumed that the selection is centred in the
heart lay, and the change in pressure is determined by the distance
from the centre.

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