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different agents that improve conditions for extracting oil from the
depths. Pumped into the reservoir water, steam, hydrocarbon gases
and other substances. The injection rate these substances and their
total amount and rate at which they extract the surface with
production wells - important indicators of the technological
development process.

2.2 Reservoir energy and forces operative in
reservoirs. Oil recovery under different drives

Fluids flow to oil and gas wells because of the differential
between the formation and bottom-hole pressures. The magnitude
of this pressure differential depends on the rate of liquid (or gas)
withdrawals from the well, the physical properties of the reservoir
rocks and fluids and also on the type of reservoir energy that
causes oil and gas to move.
Until quite recently, it was considered that the influence
of each well extends to a comparatively small area of the
formation around the bottom hole so that each well had a limited
drainage area. This view proved to be erroneous. It is now
definitely established that the whole area of every oil and gas
reservoir, together with the wells constitutes a single hydraulically
interconnected system (unless, of course, the formation is split up
into separate blocks by tectonic dislocations). Thus the influence
of producing wells drive area, right up to the boundaries of the
reservoir.
Hence it follows that the type and reserves of energy and
forces operative in the reservoir that drives the oil and gas to the
bottom holes of wells must be considered in the structure of the
entire reservoir and of the adjacent areas, and also in relation to the
properties of the reservoir fluids and the rocks of the entire
reservoir.

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